Southwest Research-Extension Center Field Day 2019

Agricultural research was conducted at the Southwest Research-Extension Center in Kansas. Topics include cropping, tillage, soil fertility, and weed science.


Introduction
To stabilize crop yields, dryland rotations in western Kansas commonly include fallow to accumulate soil water. Fallow is relatively inefficient at storing and utilizing precipitation when compared to storage and utilization of precipitation received during the growing season. Fallow periods increase soil erosion and organic matter loss (Blanco and Holman, 2012), and represent a large economic cost to producers. Forages are valuable feedstuff to the cow/calf, stocker, cattle feeding, and dairy industries throughout the region (Hinkle et al., 2010). Forages do not require as much water to make a crop as grain crops. Forages grown in place of fallow can increase precipitation use efficiency, improve soil quality, and increase profitability (Holman et al., 2018). This study tests several forage rotations for water use efficiency, forage quality, yield, and profitability.
Annual forages are grown for a shorter period and require less water than traditional grain crops. Including annual forages into the crop rotation might enable increasing cropping system intensity and opportunistic cropping. "Opportunistic cropping" or "flex cropping" is the planting of a crop when conditions (soil water and precipitation outlook) are favorable, and fallowing when unfavorable. Wheat yields following spring annual forages such as oat (O) were similar to wheat yields following fallow in a wheat-fallow rotation in non-drought years, but wheat yields were reduced in drought years (Holman et al., 2012). This indicates the opportunity to intensify the cropping system in favorable years. Forage producers in the region commonly grow continuous winter triticale (T), winter triticale or summer crop silage, or forage sorghum hay (S). However, they lack a proven rotation concept for forages such as that developed for grain crops (e.g. winter wheat-summer crop-fallow). Continuous winter triticale often develops winter annual grass problems, while continuous forage sorghum produces lower quality forage than triticale. Producers are interested in identifying forage rota-tions that increase pest management control options, spread out equipment and labor resources over the year, reduce the impact of variable weather risks, and increase profitability. Growing forages throughout the year greatly reduces the risk of crop failure due to variable precipitation.
Growing winter triticale (T) or forage sorghum (S) double cropped (T/S/T), yielded 30% less than non-double crop yields (T-S-O) (P ≤ 0.05) near Garden City, KS, between 2007 and 2010. Double cropping increased forage production's annual yield 40% more than growing one crop annually (Holman et al., 2012). However, crop establishment was more challenging and crop growth was highly dependent on growing season precipitation in the double-crop rotation compared to annual cropping. Due to the high cropping intensity it was also challenging to implement timely field operations in the double crop system. An intermediate cropping intensity of three crops grown in two years or four crops in three years might be a successful crop rotation in western Kansas.
Recently in western Kansas, glyphosate-resistant kochia (Kochia scoparia) was identified, and several other grasses (e.g. tumble windmill grass and red three-awn) are already tolerant of glyphosate and other herbicides. Although continuous no-till was shown to provide better water conservation and crop yields, this result is contingent upon being able to control weeds with herbicides during fallow. Limited information is available on the effect of occasional strategic tillage to control herbicide-tolerant weeds on forage yield. Yield of forage crops following tillage might not be affected as much as in grain crops, since forages require less water. Information is needed on the effects of occasional tillage in forage based cropping systems. Year 3: forage sorghum; Year 4: spring oat (single tillage after spring oat, min-tillage): (T/S-S-S-O min-tillage) 6. Year 1: winter triticale; Year 2: forage sorghum; Year 3: spring oat (no-tillage): (T-S-O) Winter triticale was planted at the end of September, spring oat was planted the beginning of March, and forage sorghum was planted the beginning of June. Crops were harvested at early heading to optimize forage yield and quality (Feekes 10.1) (Large 1954). Each year, winter triticale was harvested approximately May 15, spring oat was harvested approximately June 1, and forage sorghum was harvested approximately the end of August. Forage yields were determined from a 3-× 30-ft area cut 3 in. high using a small plot Carter forage harvester from each plot. Forage yield and nutritive value (protein, fiber, and digestibility) were measured at each harvest. Gravimetric soil moisture content was measured at planting and harvest to a depth of 6 ft using 1-ft increments. Precipitation storage efficiency (% of precipitation stored during the fallow period) was quantified for each fallow period, and crop water use efficiency (forage yield divided by soil water used plus precipitation) was determined for each crop harvest.
Crop yield response to plant available water (PAW) at planting was used to develop a yield prediction model based on historical or expected weather conditions. Most producers use a soil probe rather than gravimetric sampling to determine soil moisture status, so soil penetration with a Paul Brown soil probe was used four times per plot at planting to estimate soil water availability. Previous studies found a soil moisture probe provided a practical, easy way to determine soil moisture level and crop yield potential. Profitable forage and tillage systems identified in this study will benefit producers in the High Plains region.

Rotation Yield
Annual rotation yield was determined by measuring total yield for the rotation and dividing by the number of years in the rotation. This method allowed for comparing rotations of different years to each other for annual forage production (Table 1 and Tillage generally increased the yield of triticale and thus the yield of T/S-S-O was im-proved with tillage, but yield improvement in the 4-yr rotation was not as evident due to triticale occurring less frequently in the rotation.
Forage yield per crop harvest was determined for each rotation since planting and harvesting expenses are the major expenses to growing a crop; yield and value per ton are the major income components. Crop rotations with greater yield per harvest are likely to be more profitable compared to rotations with low yield per harvest since some of the variable and fixed expenses are less. Although oat and triticale yield less than forage sorghum, they are also higher in crude protein and digestibility and are worth more per unit than forage sorghum. A full economic analysis of rotations will be completed at the conclusion of this study. In 2013, S-S had the greatest yield per harvest, and all other rotations had similar yields per harvest (Table 1

Crop Yield
Full-season sorghum either grown after T/S or S yielded similarly across rotations ( Figure 3). Double-crop forage sorghum yielded less than full-season forage sorghum, but varied greatly from year to year based on precipitation during the growing season. Double crop forage sorghum yielded 70% less than full-season in 2013, 7% less in 2014, 12% less in 2015, 10% less in 2016, 38% less in 2017, and 15% less in 2018. Across all years, double-crop (6,160 lb/a) averaged 17% less than full-season forage sorghum (7,460 lb/a). The lower yield of double-crop forage sorghum was due to less available soil moisture at planting. Sorghum yield was not affected by tillage or length of rotation, although there was a tendency for no-till forage sorghum yields to be greater than mintill yields.
Triticale yield was not affected by length of rotation but was affected by tillage. Averaged across years, triticale in min-tillage (3,260 lb/a) yielded 128% more than no-tillage (2,550 lb/a). The only tillage in this study occurred in the fallow period before triticale and, in this study, benefitted the triticale crop. The exception was in 2017 when notill (1,869 lb/a) yielded more than min-till (1,518 lb/a). Other studies and producers have found tillage ahead of a winter wheat crop has minimal impact on yield and can improve weed control, but tillage ahead of grain sorghum often reduced grain yield. For these reasons, tillage was only used ahead of triticale and, similar to winter wheat, did not reduce yields, but actually increased yields in the first 4 years of this study.
Oats failed to make a crop in 2013 due to drought conditions and varied by year due to differences in growing season conditions. Oat forage yield was 400 lb/a in 2014, 4,900 lb/a in 2015, 2,300 lb/a in 2016, 883 lb/a in 2017, and 300 lb/a in 2018. Yields in 2015 and 2016 were higher than other years due to very favorable spring precipitation and cool temperatures. Oat yield was not affected by tillage or crop rotation.

Soil Water
Plant available water at planting was measured to a 6-foot soil depth, and soil water content varied by year and planting period. Soil water was greatest for full-season forage sorghum planting averaging 7.7 in. across treatments, which was more than double crop forage sorghum that averaged 5.6 in. No-till triticale (3.9 in.) was less than min-till triticale (5.9 in.). At oat planting (March) PAW averaged 3.9 in. (Figure 4).
Water use efficiency (WUE) was greatest in forage sorghum, with full-season averaging 597 lb/a/in. and double-crop producing 555 lb/a/in. Water use efficiency for winter triticale averaged 343 lb/a/in., and oat was 250 lb/a/in. The yield potential and thus water use efficiency was greater with forage sorghum than triticale or oat. However, when precipitation was favorable during a particular growing season, such as oat in 2015, the WUE of oat was comparable to forage sorghum. In years with moisture stress, WUE of double-crop forage sorghum was less than full-season, but in favorable moisture years WUE of double-crop was greater than full-season ( Figure 5).
Precipitation storage efficiency (PSE) varied by fallow period and ranged from 9% ahead of winter triticale to 40% for full-season forage sorghum. Precipitation storage ahead of double-crop forage sorghum was 32% and ahead of oat planting was 22% ( Figure 6).

Introduction
Annual forage crops are grown for a shorter time and require less moisture than traditional grain crops. Including annual forages in the cropping system might enable increased cropping intensity and opportunistic cropping. "Opportunistic cropping" or "flex cropping" is the planting of a crop when conditions (soil water and precipitation outlook) are favorable and fallowing when unfavorable. Forage producers in the region commonly grow winter triticale, forage sorghum, or spring triticale/oat. Producers are interested in forage crop rotations that enable increased pest management control options, spread out equipment and labor resources over the year, reduce weather risk, and increase profitability. Growing forages throughout the year greatly reduces the risk of crop failure. Understanding the yield relationship to PAW and GSP could help producers better meet their forage needs.

Study Objectives
1. Quantify yield relationship of winter, spring, and summer forages with PAW and GSP. 2. Determine water use efficiency of winter, spring, and summer forages.

Experimental Procedures
Annual forages were grown as part of several different rotation experiments near Garden City, KS. Plant available water, growing season precipitation, and forage yield were measured annually. Data for winter triticale and forage sorghum were available from 2008 through 2018, and spring triticale from 2012 through 2018.
Annually, winter triticale was planted at the end of September, spring triticale was planted at the beginning of March, and forage sorghum was planted at the beginning of June. Crops were harvested at early heading to optimize forage yield and quality (Feekes 10.1) (Large 1954). Annually, winter triticale was harvested approximately May 15, spring oat was harvested approximately June 1, and forage sorghum was harvested at approximately the end of August. Forage yields were determined from a 3-× 30-ft area cut 3 in. high using a small plot Carter forage harvester for each plot. Forage yield was measured at each harvest. Gravimetric soil moisture content was measured at planting and harvest to a depth of 6 ft using 1-ft increments. Precipitation storage efficiency (percent of precipitation stored during the fallow period) was quantified for each fallow period, and crop water use efficiency (forage yield divided by soil water used plus precipitation) was determined for each crop harvest. Crop yield response to plant available water at planting was regressed to estimate yield. These yield data will eventually be used to develop a yield prediction model based on historical or expected weather conditions when sufficient years of data are obtained.
Data produced by this study will be used to evaluate the economics of forage rotations and tillage. Production costs and returns will be calculated using typical values for the region. The implication of using forages on crop insurance dynamics and risk exposure is a critical component of a producer's decision-making process and will be evaluated at the conclusion of this study.

Winter Triticale
Winter triticale forage yield was correlated to PAW and GSP, although yield response was highly variable. Plant available water explained approximately 12% and GSP explained 2% of the variability in forage yield (Figures 1 and 2). Together, PAW and GSP explained 48% of the variability in forage yield ( Figure 3). For every inch of water used (soil water plus GSP), yield was increased 640 lb/a. Averaged across the study period, yield was 3,400 lb/a.

Spring Triticale
Spring triticale forage yield was significantly correlated to PAW and GSP, but yield response was highly variable. Plant available water explained approximately 5% and GSP explained 8% of the variability in forage yield (Figures 4 and 5). Combining PAW and GSP explained only 14% of the yield variability; suggesting something other than moisture, most likely temperature, greatly impacts yield ( Figure 6). In years with cool spring temperatures, spring growth is promoted, but if temperatures become high, growth is stopped. For every inch of water used (soil water plus GSP), yield was increased 193 lb/a. Averaged across the study period, yield was 1,400 lb/a.

Forage Sorghum
Forage sorghum yield was correlated to PAW but not GSP, and yield response was variable. Plant available water explained approximately 19% and GSP explained 7% of the variability in forage yield (Figures 7 and 8). Together, PAW and GSP explained 26% of the variability in forage yield ( Figure 9). For every inch of water used (soil water plus GSP), yield was increased 445 lb/a. Averaged across the study period, yield was 5,700 lb/a.       Integrated Grain and Forage Rotations J. Holman, A. Obour, A. Schlegel, T. Roberts, and S. Maxwell Summary Many producers are interested in diversifying their operations to include livestock or grow feed for the livestock industry. By integrating forages into the cropping system, producers can take advantage of more markets and reduce risk. Forages require less water to make a crop than grain crops, so the potential may exist to reduce fallow by including forages in the crop rotation. Reducing fallow through intensified grain/forage rotations may increase profitability and sustainability compared to existing crop rotations.

References
This study started in 2013, with crops grown in-phase beginning in 2014. Results showed grain crops were more sensitive to moisture stress than forage crops. Growing a double-crop forage sorghum after winter wheat reduced grain sorghum yield the second year, but did not reduce second-year forage sorghum yield. Growing a double-crop forage sorghum, followed by second-year forage sorghum, could intensify and increase profitability of the cropping system. Since other research has found cropping intensity should be reduced in dry years, caution should be used when planting double-crop forage sorghum by evaluating the soil moisture conditions and precipitation outlook after wheat harvest. The "flex-fallow" concept could be used to make a decision on whether to plant double-crop forage sorghum to increase the chance of improving cropping system profitability. This research showed forages are more tolerant to moisture stress than grain crops and the potential exists to increase cropping intensity by integrating forages into the crop rotation.

Introduction
Interest in growing forages and reducing fallow has necessitated research on soil, water, and crop yields in intensified grain/forage rotations. Fallow stores moisture, which helps stabilize crop yields and reduces the risk of crop failure. However, only 25-30% of the precipitation received during the fallow period of a no-till wheat-sorghum-fallow rotation is stored. The remaining 75-70% precipitation is lost, primarily due to evaporation. Moisture storage in fallow is more efficient earlier in the fallow period, when the soil is dry, and during the winter months when the evaporation rate is lower. It may be possible to increase cropping intensity without reducing crop yields by using forage crops in the rotation. This study evaluated integrated grain/forage rotations compared to traditional grain-only crop rotations.

Experimental Procedures
A study beginning in 2013 at the Kansas State University Southwest Research-Extension Center near Garden City, KS, evaluated various integrated grain and forage rotations compared to a no-till wheat-grain sorghum-fallow rotation. All phases of the rotation were present each year and in-phase by 2014. A total of 10 crop rotations were evaluated (Table 1). The study design was a split-plot randomized complete block design with four replications. Crop phase (wheat-sorghum-fallow) was the main plot and alternative crop choices were the split-plot. Each split-plot was 30-ft wide × 120-ft long.
"Flex-fallow" is a spring planting decision based on current soil moisture condition and seasonal outlook. Spring oats were planted when 12 inches or more of plant available water (PAW) was determined available by using a Paul Brown moisture probe, and seasonal precipitation forecasted outlook was neutral or favorable; otherwise the treatment was left fallow. The flex-fallow treatment was intended to take advantage of growing a crop during the fallow period in wet years and fallowing in dry years. A flex-fallow crop was planted in 2013, 2016, and 2019, but not in 2014, 2015, 2017, or 2018.
Each year, winter triticale was planted approximately October 1. Spring crops were planted as early as soil conditions allowed, ranging from the end of February through the middle of March. Wet spring conditions delayed planting in 2019. Spring forage crops were harvested approximately June 1. Forage sorghum was either planted around June 1 for full-season or following wheat harvest around July 1 for double-crop. Forage biomass yields were determined from a 3-× 120-ft area cut 3 in. high using a small plot Carter forage harvester. Winter wheat and grain sorghum were harvested with a small plot Wintersteiger combine from a 6.5-× 120-ft area at grain maturity.
Volumetric soil moisture content was measured at planting and harvest of winter wheat, grain sorghum, forage sorghum, spring oat, or fallow using a Giddings soil probe by 1-ft increments to a 6-ft soil depth. In addition, volumetric soil content was measured in the 0-3 in. soil depth at wheat planting to quantify moisture in the seed planting depth. Grain yield was corrected for moisture content, and test weight was measured using a grain analysis computer (GAC 2100, Dickey-John). Seed weight was determined from a 1,000-seed count using a seed counter computer (801, Seedburo). Grain samples were analyzed for nitrogen content.

Winter Wheat
Winter wheat yield, plant available moisture at planting, water use efficiency, and precipitation storage efficiency prior to planting were not affected by whether forage sorghum or grain sorghum were grown in place of one another in the rotation ( Figure  1). Wheat yields were low and treatments averaged 14 bu/a or less from 2015 through 2018. Wheat yield was low in all years due to severe rabbit feeding and dry conditions. A flex-crop was grown in 2013, 2016, and 2019, but not 2014, 2015, 2017, or 2018. Dry conditions developed soon after planting a flex-crop in 2013, and growing a flexcrop in place of fallow reduced wheat yield 67% in 2014 and did not affect 2017 yield. Dry fall conditions and rabbit feeding killed the wheat crop in 2016 and there was no yield that year. Soil moisture was dry in the fall of 2017 and some of the wheat did not emerge until spring. Conditions were again very dry during the winter and spring of 2018.
Previous research found growing oats in place of fallow reduced wheat yields when wheat yield potential was less than 50 bu/a. For the years of this study, extreme dry weather and rabbit feeding masked any differences in wheat yield attributed to the treatments.

Grain Sorghum
Grain sorghum yield was highly correlated with plant available moisture at planting, which explained 40% of the variability in grain yield ( Figure 2). Including growing season precipitation in the model did not improve yield predictability (data not shown). Approximately 7.2 bushels were grown for every acre-inch of plant available water at planting. Plant available moisture was highest when forage sorghum was not double-cropped between wheat and grain sorghum (Figure 3). Higher wheat yields and residue levels improved the WUE of grain sorghum. Growing double-crop forage sorghum ahead of grain sorghum reduced grain sorghum yield 61% in 2014, 38% in 2015, 20% in 2016, 56% in 2017, and 20% in 2018. Averaged across years, growing a double-crop forage sorghum reduced the subsequent grain sorghum crop yield by 36%. Growing a forage sorghum crop after wheat reduced the amount of plant available water at planting and water use efficiency of the subsequent grain sorghum crop each year, but did not affect precipitation storage efficiency in the fallow period ahead of grain sorghum. Growing a forage sorghum crop reduced the test weight and seed weight of grain sorghum in 2015 and seed weight in 2017 and 2018.

Forage Sorghum
Forage sorghum yield was also correlated with plant available moisture at planting, but not as much as grain sorghum. Plant available moisture at planting explained approximately 17% of the variability in forage yield ( Figure 4). By including growing season precipitation in the model, 38% of the variability in forage yield was explained ( Figure  5). Approximately 450 lb of forage was grown for every inch of plant available water (PAW) at planting. Forage sorghum yields were not different across treatments in 2014, except double-crop FS in winter wheat/forage sorghum-forage sorghum-spring oat (ww/FS-fs-o) yielded 2,200 lb/a less than full-season forage sorghum in the same rotation of winter wheat/ forage sorghum-forage sorghum-spring oat (ww/fs-FS-o) (Table 4). This lower yield was most likely due to less plant available water at planting, 1.3 versus 2.1 inches. In 2014, plant available water averaged 1.0 inch ahead of double-crop forage sorghum and 4.1 inches ahead of full season forage sorghum. Most of the annual precipitation in 2014 occurred later in the year (June-September), which likely helped improve the yield of double-crop forage sorghum relative to full-season forage sorghum. In 2014, double-crop forage sorghum yielded, on average, 17% less than full-season forage sorghum (3,300 versus 3,900 lb/a). In 2015, most of the precipitation occurred earlier in the year (May-August) than 2014, which helped increase wheat yields but also resulted in comparatively less moisture at planting time of double-crop forage sorghum, 1.6 versus 7.2 inches. As a result, 2015 double-crop forage sorghum yields were reduced 70% compared to full-season forage sorghum (2,400 versus 8,000 lb/a). In 2016, moisture conditions were favorable during the growing season (June-August), resulting in good forage yields across all treatments. There were 0.8 inches more PAW at planting of the full-season compared to double-crop forage sorghum. Double crop yields were reduced on average 43% compared to full-season forage sorghum (3,900 vs. 6,900 lb/a). In 2017, most of the precipitation occurred during the spring of the year, which increased moisture storage during the fallow period but little moisture during the growing season, resulting in low yields in the double-crop forage sorghum crop. Full season forage sorghum averaged 6,700 lb/a and double-crop averaged 1,000 lb/a. In 2018, most of the precipitation fell during the second half of the growing season, resulting in good forage yields for both double and full-crop. Full season forage sorghum averaged 10,600 and double-crop averaged 8,200 lb/a. Between 2014 and 2018 full-season sorghum averaged 7,200 and double-crop averaged 4,000 lb/a. Surprisingly, second-year forage sorghum yields following double-crop forage sorghum were similar to full-season forage sorghum following wheat with fallow between wheat harvest and sorghum planting ( Figure 6). Yet forage sorghum planted after double-crop forage sorghum had an average of 3 inches less soil moisture compared to forage sorghum planted after wheat with a fallow period between crops. In dry years this difference in plant available soil water may result in yield differences, but it did not affect yield in this study. The yield plateau of a forage crop is lower than a grain crop, which might explain why there was no yield penalty for second-year forage sorghum grown after either fallow or double-crop forage sorghum. These results suggest that as long as the benefits of growing a double-crop forage sorghum crop exceeded costs, an extra forage sorghum crop could be grown in the rotation. A partial enterprise analysis of this phase of the rotation only, indicated double-crop forage sorghum yield needs to be at least 30% of full-season forage sorghum, or at least 2,000 lb/a, for a double-crop forage sorghum crop that is grazed to be profitable. The additional variable expenses of growing double-crop forage sorghum would be approximately $25.00/a.

Spring Oat
Spring oat yield was not affected by rotation treatment and yielded 564 lb/a in 2014, 1,927 lb/a in 2015, 1,877 lb/a in 2016, 1,456 lb/a in 2017, and 287 lb/a in 2018. Spring forage yields were low across years, averaging 1220 lb/a.

Conclusions
Wheat and spring oat yields were not affected by whether grain or forage sorghum were grown in place of each other in the crop rotation. Oats were grown in place of fallow in those years that indicated favorable moisture conditions. Wheat yields were reduced when oats were grown in place of fallow. Our previous fallow replacement research found wheat yield potential needed to be greater than 50 bushels for wheat yields to not be reduced by growing a crop in place of fallow. Wheat yield potential was very low in all years at 6 bu/a in 2014, 15 bu/a in 2015, failed to make grain in 2016, 8 bu/a in 2017, and 10 bu/a in 2018. The factors of rabbit feeding and low growing season precipitation caused very low wheat yield, and as a result, masked any yield difference that would be attributable to crops grown or fallow in the rotation.
Grain sorghum yield was more sensitive to moisture stress than forage sorghum. Growing a double-crop forage sorghum after wheat reduced grain yield 20-60% the second year but never reduced forage sorghum yield in the years of this study. However, with less summer precipitation, full-season forage sorghum yields might be more negatively impacted than they were in this study. Double-crop forage sorghum yields were more sensitive than full-season forage sorghum. Double-crop forage sorghum yields averaged 45% less than full-season, and in the driest growing season (2017) yields were reduced 85%. As long as double-crop forage sorghum is profitable, which we identified to be around 2,000 lb/a yield when grazed, it appears the cropping system can be intensified without negatively affecting second-year forage sorghum yield. Wheat-grain sorghum-flex-fallow ww-gs-fx 2 Wheat-grain sorghum-fallow ww-gs-fl 3 Wheat-forage sorghum-oat ww-fs-o 4 Wheat-grain sorghum-oat ww-gs-o 5 Wheat-forage sorghum-fallow ww-fs-fl 6 Wheat-forage sorghum-flex-fallow ww-fs-fx 7 Wheat/forage sorghum-forage sorghum-flex-fallow ww/fs-fs-fx 8 Wheat/forage sorghum-grain sorghum-flex-fallow ww/fs-gs-fx 9 Wheat/forage sorghum-forage sorghum-fallow ww/fs-fs-fl 10 Wheat/forage sorghum-grain sorghum-fallow ww/fs-gs-fl   Table 1 for treatments.   Table 1 for treatments.   Table 1 for treatments.

Alternative Cropping Systems with Limited Irrigation
A. Schlegel and D. Bond Summary A limited irrigation study involving four cropping systems and evaluating four crop rotations was initiated at the Southwest Research-Extension Center near Tribune, KS, in 2012. The cropping systems were two annual systems (continuous corn [C-C] and continuous grain sorghum [GS-GS]) and two 2-year systems (corn-grain sorghum [C-GS] and corn-winter wheat [C-W]). In 2018, corn yields were similar for all rotations, although averaged across the past 6 years, corn yields were greater following wheat than following corn. There were no significant differences in grain sorghum yields in 2018, which was similar to the multi-year average. Wheat yields were near the multiyear average.

Experimental Procedures
A crop rotation study under sprinkler irrigation at the Kansas State University Southwest Research-Extension Center near Tribune, KS, was initiated in the spring of 2012.
The study evaluates four different crop rotations with a limited irrigation allocation. The rotations include 1-and 2-year rotations. The crop rotations are 1) continuous corn; 2) corn-winter wheat; 3) corn-grain sorghum; and 4) continuous grain sorghum (a total of 6 treatments). All rotations are limited to 10 inches of irrigation water annually. All crops are grown no-till, while other cultural practices (hybrid selection, fertility practices, weed control, etc.) are selected to optimize production. All phases of each rotation are present each year and replicated four times. Irrigations are scheduled to supply water at the most critical stress periods for the specific crops and limited to 1.5 inches per week. Soil water is measured at planting, during the growing season, and at harvest in 1-ft increments to a depth of 8 ft. Grain yields are determined by machine harvest. Nitrogen fertilizer (UAN) was surface applied (stream) in March to all crops (240 lb N/a for corn, 160 lb N/a for sorghum, and 120 lb N/a for wheat). Corn was planted on May 3, 2018, and harvested on September 25, 2018. Grain sorghum was planted on June 4, 2018, and harvested on November 28, 2018. Wheat was planted on October 13, 2017, and harvested on July 6, 2018.

Results and Discussion
Wheat yields in 2018 (45 bu/a) were slightly less than the long-term average (50 bu/a) (Tables 1 and 2). Precipitation was near normal from April through September followed by a wet October that delayed sorghum harvest. Corn yields in 2018 were above the long-term average with no differences among rotations. In contrast to previous years, grain sorghum yields were greater following sorghum than corn, but because of extreme variability the difference was not significant. The delayed harvest caused by above-normal late fall precipitation caused the grain sorghum to lodge, which may have reduced overall yields and increased variability. On average, corn yields are greatest following wheat and least following corn, with little difference in grain sorghum yields following corn or sorghum (Table 2).
Available soil water at corn and sorghum planting and harvest was similar for all rotations in 2018 (Table 3). Fallow efficiency was near zero or often negative because of wet soils at harvest in 2017. For wheat, available soil water at planting and harvest was greater than the 6-year average (Table 4). Averaged across the 6-year period, fallow accumulation prior to corn was greater following wheat than following sorghum or corn; however, fallow efficiency was greatest following sorghum (shortest fallow period). There were no differences in fallow accumulation or efficiency for grain sorghum following corn or sorghum. There were no differences in crop water use due to rotation for either crop.

Introduction
Previous research has shown lower dryland wheat and grain sorghum yields with reduced tillage compared with no-tillage in a wheat-sorghum-fallow (WSF) rotation. The reduced tillage systems generally used four or more tillage operations in the 3-yr rotation. With increased incidence of herbicide-resistant weeds, the use of a complete no-tillage system may not be economical and tillage may be needed for effective control. The objective of the research project is to determine the effect of a single tillage operation every 3 years on grain yields in a WSF rotation.

Procedures
Research on occasional tillage intensities in a predominantly no-tillage WSF rotation at the Kansas State University Southwest Research-Extension Center research stations at Garden City and Tribune were initiated in 2012. The three tillage treatment intensities in this study are a single tillage in May or June during fallow, a single tillage after wheat harvest, and a complete no-tillage system. A sweep plow (Minimizer by Premier Tillage) was used for all tillage operations. When needed, herbicides were used to control weeds during fallow for all treatments. All treatments used herbicides for in-crop weed control. All other cultural practices (variety/hybrid, seeding rate, fertilization, etc.) were the same for all treatments.

Results and Discussion
Weeds were effectively controlled in all treatments and there were no visual differences in weed population across treatments.
At Tribune, wheat yields were 57-58 bu/a in 2018 compared with 41-43 bu/a for the 5-year average (Table 1). There were no significant yield differences among tillage treatments in any year or across years. Grain sorghum yields were very good in 2018 ranging from 115-130 bu/a (Table 2). Similar to wheat, there were no significant yield differences among tillage treatments in any year. However, averaged across years, NT produced greater yields than tillage post-wheat harvest.
At Garden City, wheat yields in 2018 were very low at 2-7 bu/a (Table 3). Between November 1, 2017, and April 1, 2018, 0.4 inches of precipitation was received, compared to the long-term period average of 3.46 inches. Wheat yields in 2014 were severely reduced by hail. There were no significant yield differences among tillage treatments in any year or averaged across years. Grain sorghum yields in 2018 were good with all yields near 90 bu/a or greater (Table 4). Similar to wheat, there were no significant yield differences among tillage treatments in any year or averaged across years.
In other research (Schlegel et al., 2018), reduced tillage systems (with four tillage operations) produced lower yields than a complete no-tillage system in a WSF rotation. However, in this study, a single tillage operation in a 3-yr WSF rotation generally had little effect on wheat or grain sorghum yields from 2014-2018 at Garden City or Tribune, KS.

Introduction
The change from conventional tillage to no-tillage cropping systems has allowed for greater intensification of cropping in semi-arid regions. In the central High Plains, wheat-fallow (1 crop in 2 years) has been a popular cropping system for many decades. This system is being replaced by more intensive wheat-summer crop-fallow rotations (2 crops in 3 years). There has also been increased interest in further intensifying the cropping systems by growing 3 crops in 4 years or continuous cropping. This project evaluates several multi-crop rotations that are feasible for the region, along with alternative systems that are more intensive than 2-or 3-year rotations. The objectives are to 1) enhance and stabilize production of rainfed cropping systems using multiple crops and rotations, using best management practices to optimize capture and utilization of precipitation for economic crop production, and 2) enhance adoption of alternative rainfed cropping systems that provide optimal profitability.

The crop rotations are 2-year (wheat-fallow [WF]); 3-year (wheat-grain sorghum-fallow [WSF] and wheat-corn-fallow [WCF]); 4-year (wheat-corn-sorghum-fallow [WCSF]
and wheat-sorghum-corn-fallow [WSCF]); and continuous sorghum [SS]. All rotations are grown using no-tillage (NT) practices except for WF, which is grown using reduced-tillage (RT). All phases of each rotation are present each year. Plot size is a minimum of 100 × 450 ft. In most instances, grain yields were determined by harvesting the center 60 ft (by entire length) of each plot with a commercial combine and determining grain weight with a weigh-wagon or combine yield monitor. Soil water was measured in 12-inch increments to 96 inches near planting and after harvest either gravimetrically (RT WF) or by neutron attenuation (NT plots).

Results and Discussion
Precipitation averaged 102% of normal (17.90 in.) across the 11-year study period and was near normal (+/-15%) in 7 out of 11 years with three wet years (>20% above normal) and one exceptionally dry year (42% of normal) ( Figure 1). Fallow accumulation, fallow efficiency, and profile available water at wheat planting was greater with WF than all other wheat rotations (Table 1). The fallow efficiencies of the 3-and 4-year NT rotations were only 54-68% of WF under RT. With more water available, crop water use was also greater with WF than with wheat in other rotations. There were no differences in available water at wheat planting or crop water use among the 3-and 4-year rotations.
Fallow accumulation prior to corn planting and profile available soil water at planting was greater following wheat (WCF or WCSF) than following grain sorghum (WSCF) ( Table 1). However, the fallow period following wheat was longer, resulting in low fallow efficiencies (~17%) following wheat and only 20% following sorghum. Similar to wheat, corn water use was greater with greater available soil water at planting. Grain sorghum responded similarly to corn, with greater fallow accumulation and soil water at planting (and greater crop water use) when following wheat than following corn or sorghum. Again, fallow efficiencies prior to grain sorghum were low (15-20%).
Wheat yields were above normal in 2018 ( Figure 2). The effect of cropping systems was not consistent across years, with WF sometimes in the highest yielding group and sometimes in the lowest yielding group. Averaged across the 11 years, cropping system had little effect on wheat yields.
Grain sorghum yields were very good in 2018 with yields greater than 100 bu/a when following wheat ( Figure 3). Sorghum following corn produced 20 bu/a less yield than following wheat, and continuous sorghum yields were 20 bu/a less than following corn. Average grain sorghum yields following wheat were approximately 50% greater than following corn or sorghum.
In contrast to sorghum, corn yields were poor in 2018 ( Figure 4) with all rotations yielding 40 bu/a or less. Corn yields following wheat in either the 3-or 4-year rotations were always greater than corn yields following grain sorghum, except in 2015 where corn yields following sorghum (wsCf) were greater than wCf. On average, corn yields following wheat were about 50% greater than following grain sorghum.
When examining grain yields across crops, the greatest yields were produced by grain sorghum following wheat (either wSf or wScf) of > 80 bu/a ( Figure 5). These yields were about 50% greater than corn following wheat (wCf or wCsf). Sorghum yields following wheat were about 50% greater than sorghum following corn or sorghum (wcSf or SS), while corn yields following wheat (wCf or wCsf) were also about 50% greater than following sorghum.         Tillage Intensity in a Long-Term Wheat-Sorghum-Fallow Rotation

Summary
This study was initiated in 1991 at the Kansas State University Southwest Research-Extension Center near Tribune, KS. The purpose of the study was to identify the effects of tillage intensity on precipitation capture, soil water storage, and grain yield in a wheat-sorghum-fallow rotation. Grain yields of wheat and grain sorghum increased with decreased tillage intensity in a wheat-sorghum-fallow (WSF) rotation. In 2018, available soil water at sorghum planting was greater for no-tillage (NT) than reduced tillage (RT) which was greater than conventional tillage (CT). For wheat there was a similar pattern as sorghum, with available soil water at wheat planting being in the order of NT>RT>CT. Averaged across the 18-yr study, available soil water at wheat planting was similar for NT and RT and approximately 1 inch greater than CT. Average available soil water at sorghum planting was greater in the order RT≥NT>CT. Averaged across the past 18 years, NT wheat yields were 5 bu/a greater than RT and 8 bu/a greater than CT. Grain sorghum yields in 2018 were twice as great in long-term NT compared to short-term NT with the lowest yields with CT. Averaged across the past 18 years, sorghum yields with long-term NT have been 58% greater than with short-term NT (76 vs. 48 bu/a).

Experimental Procedures
Research on different tillage intensities in a WSF rotation at the Tribune, KS, unit of the Southwest Research-Extension Center was initiated in 1991. The three tillage intensities in this study are conventional (CT), reduced (RT), and no-tillage (NT). The CT system was tilled as needed to control weed growth during the fallow period. On average, this resulted in 4 to 5 tillage operations per year, usually with a blade plow or field cultivator. The RT system originally used a combination of herbicides (1 to 2 spray operations) and tillage (2 to 3 tillage operations) to control weed growth during the fallow period; however, in 2001, the RT system was changed to using NT from wheat harvest through sorghum planting (short-term NT) and CT from sorghum harvest through wheat planting. The NT system exclusively used herbicides to control weed growth during the fallow period. All tillage systems used herbicides for in-crop weed control.

Soil Water
The amount of available water in the soil profile (0-8 ft) at wheat planting varied greatly from year to year ( Figure 1). In 2018, available soil water at wheat planting was greater with NT than RT and least with CT. Averaged across the 18-yr study, available soil water at wheat planting was similar for RT and NT (~ 8 inches) and approximately 1 inch greater than CT.
Similar to wheat, the amount of available water in the soil profile at sorghum planting varied greatly from year to year ( Figure 2). In 2018, available soil water at sorghum planting was greater with NT than RT and least with CT. On average, available soil water at sorghum planting was similar for NT and RT and about 1.5 inches greater than CT.

Grain Yields
Wheat yields in 2018 were greater than the long-term average (Table 1). Since 2001, wheat yields have been depressed in 11 of 18 years, primarily because of lack of precipitation, winterkill (2015), and disease (2017). Reduced tillage and NT increased wheat yields. On average, wheat yields were 8 bu/a higher for NT (26 bu/a) than CT (18 bu/a). Wheat yields for RT were 3 bu/a greater than CT even though both systems had tillage prior to wheat. Yields of NT were significantly less than CT or RT in only 1 of the 18 years.
Grain sorghum yields in 2018 were greater than the long-term average (Table 2). Sorghum yields were twice as great with NT than RT (116 vs. 57 bu/a) while CT yields were the least (35 bu/a). The yield benefit from reducing tillage is greater for grain sorghum than wheat. Grain sorghum yields for RT averaged 18 bu/a more than CT, whereas NT averaged 28 bu/a more than RT. For sorghum, both RT and NT used herbicides for weed control during fallow, so the difference in yield could be attributed to short-term compared with long-term NT. This yield benefit with long-term vs. shortterm NT has been observed in most years since the RT system was changed in 2001. Averaged across the past 18 years, sorghum yields with long-term NT have been 58% greater than with short-term NT (76 vs. 48 bu/a).    Cropping and Tillage Systems

Wheat and Grain Sorghum in Four-Year Rotations
A. Schlegel, J. Holman, and A. Burnett

Summary
In 1996, an effort began to quantify soil water storage, crop water use, and crop productivity on dryland systems in western Kansas. Research on 4-year crop rotations with wheat and grain sorghum was initiated at the Southwest Research-Extension Center near Tribune, KS. Rotations were wheat-wheat-sorghum-fallow (WWSF), wheat-sorghum-sorghum-fallow (WSSF), and continuous wheat (WW). Soil water at wheat planting averaged about 9 in. following sorghum, which is about 3 in. more than the average for the second wheat crop in a WWSF rotation. Soil water at sorghum planting was only about 1 in. less for the second sorghum crop compared with sorghum following wheat. Grain yield of recrop wheat averaged about 75% of the yield of wheat following sorghum. Grain yield of continuous wheat averaged about 60% of the yield of wheat grown in a 4-year rotation following sorghum. Generally, wheat yields were similar following one or two sorghum crops. Similarly, average sorghum yields were the same following one or two wheat crops. Yield of the second sorghum crop in a WSSF rotation averages ~63% of the yield of the first sorghum crop.

Introduction
In recent years, cropping intensity has increased in dryland systems in western Kansas. The traditional wheat-fallow system is being replaced by wheat-summer crop-fallow rotations. Research was conducted to better understand if more intensive cropping is feasible with concurrent increases in no-tillage. Objectives of this research were to quantify soil water storage, crop water use, and crop productivity of 4-year and continuous cropping systems.

Experimental Procedures
Research on 4-year crop rotations with wheat and grain sorghum was initiated in 1996 at the Tribune unit of the Southwest Research-Extension Center. Rotations were WWSF, WSSF, and WW. No-tillage was used for all rotations except for the first two years where reduced tillage was used for wheat following sorghum. Available water was measured in the soil profile (0 to 6 ft) at planting and harvest of each crop. The center of each plot was machine harvested after physiological maturity, and yields were adjusted to 12.5% moisture.

Soil Water
The amount of available water in the soil profile (0 to 6 ft) at wheat planting varied greatly from year to year ( Figure 1). In 2018, available soil water was greater for wheat following sorghum and for wheat following wheat compared to the long-term average. Soil water was similar following fallow after either one or two sorghum crops and averaged about 9 in. across the 22-year study period. Water at planting of the second wheat crop in a WWSF rotation was generally less than at planting of the first wheat crop, except in 1997 and 2003. Soil water for the second wheat crop averaged more than 3 in. (or about 40%) less than that for the first wheat crop in the rotation. Continuous wheat averaged approximately 0.8 in. less water at planting than the second wheat crop in a WWSF rotation.
Similar to wheat, the amount of available water in the soil profile at sorghum planting varied greatly from year to year ( Figure 2) and available water at sorghum planting was greater than the long-term average. Soil water was similar following fallow after either one or two wheat crops and averaged about 8 in. over 23 years. Water at planting of the second sorghum crop in a WSSF rotation was generally less than that at planting of the first sorghum crop. Averaged across the entire study period, the first sorghum crop had about 1.3 in. more available water at planting than the second crop.

Grain Yields
In 2018, wheat yields after fallow were greater than the long-term average while wheat yields after wheat were less than the long-term average (Table 1). Averaged across 22 years, recrop wheat (the second wheat crop in a WWSF rotation) yielded about 75% of first-year wheat crop in WWSF. Before 2003, recrop wheat yielded about 70% of first-year wheat. Wheat yields following two sorghum crops are 2 bu/a greater than following one sorghum crop. In most years, continuous wheat yields have been similar to recrop wheat yields, but in several years (2003, 2007, 2009, and 2014), recrop wheat yields were considerably greater than continuous wheat yields. However, in 2018, continuous wheat yields were considerably less than recrop wheat yields (6 vs. 24 bu/a).
Sorghum yields in 2018 for all rotations were higher than the long-term average yields. This is the fourth year in a row of above average sorghum yields. Sorghum yields following wheat were 37-50 bu/a greater than the long-term average (Table 2). Sorghum yields were similar following one or two wheat crops, which is consistent with the longterm average. The second sorghum crop yields were 51% of the first sorghum crop in 2018, which is less than the long-term average of about 63%. Year  Year Wheat-sorghum-sorghum-fallow (WSSF) and wheat-wheat-sorghum-fallow (WWSF). ANOVA = analysis of variance. LSD = least significant difference. ' 9 6 ' 9 7 ' 9 8 ' 9 9 The objective of the study is to identify appropriate seeding rates for dryland winter wheat in western Kansas. Averaged across varieties, a seeding rate of 60 lb/a seemed to be adequate at all locations in 2015. However, with higher yields in 2016, a higher seeding rate (75 lb/a) was beneficial. Although yields were less in 2017 than 2016, a seeding rate of 75 lb/a generally produced the highest yields. In 2018, yield increased with increased seeding rate. The wheat variety T158 was the highest yielding (or in the highest group) at all locations in 2015. Other varieties may have been affected by differential response to stripe rust and winter injury resulting in lower yields. In 2016, the highest yielding variety varied by location. TAM 114 was in the highest yielding variety at each location in 2017. In 2018, Winterhawk was the lowest yielding variety. Variety selection and growing season appears to have more effect on wheat yields than seeding rate. A seeding rate of 30 or 45 lb/a, and often 60 lb/a, resulted in lower yields than the 75 or 90 lb/a rate. Yield response to seeding rate, and optimal seeding rate for any siteyear was similar across varieties.

Introduction
The purpose of this project is to determine appropriate seeding rates for dryland winter wheat in western Kansas, and to determine if the optimal seeding rate is dependent on variety. A preliminary study conducted in 2014 found no yield benefit from increasing seeding rates from 30 to 75 lb of seed/a for 4 wheat varieties at Tribune, while a similar study at Garden City suffered severe hail damage causing yields to be less than 10 bu/a. The objective is to evaluate seeding rates on grain yield of several popular wheat varieties representing a range of genetic backgrounds and tillering ability under dryland conditions at three sites in western Kansas.

Results and Discussion
Growing season precipitation was below normal for Garden City all years, but normal to above normal for Tribune and Colby. In addition, precipitation was infrequent and variable across the growing seasons. In 2015, precipitation was high in May (6.38 in. at Garden City, 6.16 in. at Tribune, and 6.42 in. at Colby) making up for a dry winter and early spring. For 2016, rainfall was above normal for Tribune, slightly below normal for Garden City, and below normal at Colby. April was wet with 5.16 in. at Tribune, 4.59 in. at Garden City, and 5.64 in. at Colby. In 2017, precipitation was above average at Tribune in April (4.67 in.) and May (5.00 in.); however, wheat streak mosaic virus reduced grain yield. At Garden City conditions were very dry in the fall of 2016 (0.3 in. between October and January), and the majority of the precipitation (6.58 in.) occurred in March and April. At Colby, conditions were extremely dry at seeding time followed by above normal precipitation in the late spring. A blizzard event on April 30 to May 1, 2017, resulted in the wheat being completely laid flat at the boot stage at Tribune and Colby with 14-20 inches of snow on top.
In 2015, averaged across seeding rates at Tribune, T158 and Winterhawk produced the greatest yields with TAM 111 producing the lowest yields ( At all sites averaged across varieties in 2015, there was a positive yield response to increased seeding rates with greatest response when increasing from 30-60 lb/a with minimal response above 60 lb/a. Wheat yields were very good at all locations in 2016 (Table 4). The response to variety and seeding rate varied greatly across locations. Averaged across seeding rates, Byrd produced the greatest yields at Tribune while it produced the lowest yields at Garden City. Winterhawk and T158 were the lowest yielding at Tribune while they were the highest yielding at Garden City and Colby. There was a significant positive yield response to increased seeding rate at Tribune and Colby but no significant response to seeding rate at Garden City.
Wheat yields were increased by increased seeding rates at all locations in 2017 (Table 5). Wheat yields were the lowest at Tribune (significant wheat streak mosaic virus damage) and greatest at Colby. TAM 114 was in the highest yielding group at all locations. The ranking of the other varieties depended upon location. The dry fall conditions in 2016 at Garden City likely reduced tiller development, resulting in reduced wheat yields at seeding rates less than 60 lb/a. Relative differences in growth stage among varieties at the time of the late spring blizzard may have affected their yield potential, however, this was very difficult to assess.
Wheat yields increased by increasing seeding rates at all locations in 2018 (Table 6). Wheat yields were lowest at Garden City and highest at Colby. Yields by variety were generally mixed with the exception of Winterhawk being the lowest yielding variety at all three locations. As seeding rate increased from 30 to 90 lb/a, yields increased by 7, 7, and 16 bu/a at Garden City, Tribune, and Colby, respectively.
Averaged across years (2015-2018), T158 was the highest yielding variety at Garden City and Colby (Table 6). Byrd was the highest yielding variety at Tribune, but the lowest yielding at the other two locations. At all locations, grain yields were increased by increased seeding rate. When averaged across all locations and years, yields were increased by 8 bu/a from increasing seeding rate from 30 to 60 lb/a and an additional 3 bu/a when seeding rate was increased to 90 lb/a. There was not a significant variety × seeding rate interaction as all varieties responded positively to increased seeding rate.
In 14 site-years of this study, a variety × seeding rate interaction has only been observed in 2 site-years. At those two site-years (Garden City and Tribune, 2015), increasing seeding rates resulted in increased yield for stripe rust-susceptible varieties. We hypothesize that higher seeding rates in the stripe rust-susceptible varieties partially compensated for lower per plant grain yield due to reduction of productive leaf area due to stripe rust. In general, the data collected in this study would not support the need for variety-specific seeding rate recommendations.

Wheat Stubble Height on Subsequent Corn and Grain Sorghum Crops
A. Schlegel and L. Haag Summary A field study initiated in 2006 at the Southwest Research-Extension Center near Tribune, KS, was designed to evaluate the effects of three wheat stubble heights on subsequent grain yields of corn and grain sorghum. Corn and sorghum yields in 2018 were greater than the long-term average. When averaged from 2007 through 2018, corn grain yields were 9 bu/a greater when planted into either high or strip-cut stubble than into low-cut stubble. Average grain sorghum yields were 6 bu/a greater in high-cut stubble than low-cut stubble. Similarly, water use efficiency was greater for high or stripcut stubble for corn and high-cut stubble for grain sorghum than for low-cut stubble.
Harvesting wheat shorter than necessary causes a yield penalty for the subsequent row crops, especially dryland corn.

Introduction
Seeding of summer row crops throughout the west-central Great Plains often occurs following wheat in a 3-year rotation (wheat-summer crop-fallow). Wheat residue provides numerous benefits, including evaporation suppression, delayed weed growth, improved capture of winter snowfall, and soil erosion reductions. Stubble height affects wind velocity profile, surface radiation interception, and surface temperatures, all of which affect evaporation suppression and winter snow catch. Taller wheat stubble is also beneficial to pheasants in postharvest and overwinter fallow periods. Using stripper headers increases harvest capacity and provides taller wheat stubble than previously attainable with conventional small-grains platforms. Increasing wheat cutting heights or using a stripper header should further improve the effectiveness of standing wheat stubble. The purpose of this study is to evaluate the effect of wheat stubble height on subsequent summer row crop yields.

Experimental Procedures
This study was conducted at the Southwest Research-Extension Center dryland station near Tribune, KS. From 2007 through 2018, corn and grain sorghum were planted into standing wheat stubble of three heights. Optimal (high) cutter-bar height is the height necessary to maximize both grain harvested and standing stubble remaining (typically around two-thirds of total plant height), the short cut treatment was half of optimal cutter-bar height, and the third treatment was stubble remaining after stripper header harvest. For 2018, these heights were 16, 8, and 24 in. (cut after 2017 wheat harvest). In 2018, corn and grain sorghum were seeded at rates of 15,000 seeds/a and 45,000 seeds/a, respectively. Nitrogen was applied to all plots at a rate of 80 lb/a. Starter fertilizer (10-34-0 nitrogen-phosphorus-potassium (N-P-K)) was surface-dribbled off-row at a rate of 7 gal/a. Plots were 40 × 60 ft, with treatments arranged in a randomized complete block design with six replications. Two rows from the center of each plot were harvested with a plot combine for yield and yield component analysis. Soil water mea-surements were obtained with neutron attenuation to a depth of 6 ft in 1-ft increments at seeding and harvest to determine water use and water use efficiency.

Results and Discussion
The 2018 growing season was drier than normal through March but near or above normal for the remainder of the year, with above normal precipitation for the year (19.81 inch in 2019 vs. normal of 17.90 inch). This produced above average yields for both corn and sorghum (Tables 1-4). With the good growing conditions, stubble height had little effect on corn yield or other parameters. When averaged across 2007 to 2018, corn yields were 9 bu/a greater in high or strip-cut than low-cut wheat stubble ( Table 2). Biomass production and water use efficiency were also greater with the taller stubble.
Grain sorghum yields in 2018 were not affected by stubble height (Table 3). When averaged across years from 2007 through 2018, the highest yields were obtained in the high-cut stubble and the lowest yields in the low-cut stubble ( Table 4). None of the other measured parameters for grain sorghum were affected by wheat stubble height except for greater water use efficiency in high-cut vs. low-cut stubble.

Summary
The farmers within the Ogallala aquifer desire to extend the usable life of this aquifer despite experiencing diminishing well capacities, thus the quest for more efficient irrigation application technologies. Mobile drip irrigation (MDI), which integrates drip lines onto a mechanical irrigation system such as a center pivot, has attracted their attention lately. The concept is that by applying water along crop rows, it was hypothesized that MDI could eliminate water losses due to spray droplet evaporation, wind drift, and reduce soil evaporation due to limited surface wetting especially before canopy closure.
A study was conducted with the following objectives: 1) compare soil water evaporation under MDI and in-canopy spray nozzles (low elevation spray application (LESA)); 2) evaluate soil water redistribution under MDI at 60-inch drip line lateral spacing; and 3) compare corn grain yield, and water productivity under MDI and LESA at two well capacities (300 and 600 gpm). The experimental design was randomized complete block with four replications and two treatments (MDI and LESA). Nozzle performance was evaluated using the Spot-on flow measurement device. Soil water evaporation was measured using 4-inch mini-lysimeters placed between corn rows. The effect of a 60-inch lateral spacing on soil water redistribution was measured using neutron attenuation to a depth of 8 feet. Corn yield was determined from harvesting two 40-foot corn rows in the center of each plot. Measured and design nozzle flow rates were similar indicating the irrigation system was performing as designed. Results indicate that soil water evaporation was lower under MDI compared to LESA by an average of 35%. Soil water was greatest at the mid-point between two drip line laterals spaced 60 inches apart at a depth of approximately 20-24 inches. These results indicate drip line spacing of 60 inches is adequate for silt loam soils of southwest Kansas. The effect of irrigation application method (MDI versus spray nozzles [LESA]) on yield at high (600 gpm) and low (300 gpm) well capacities was not statistically significant at the 5% level (P > 0.05). The effect of application method on water productivity and irrigation water use efficiency was also not significant. The lack of significant differences in yield could be attributed to the above normal rainfall received during the 2015 growing season (18 inches from May to September). However, it is worth noting that the effect of application method on end-of-season soil water was statistically significant under low well capacity (300 gpm) with mobile drip irrigation having more soil water compared to spray nozzles.

Introduction
Economies of many rural communities in the Central Plains rely heavily on irrigated agriculture. Diminishing well capacities coupled with the desire to extend the usable life of the Ogallala aquifer have stimulated the quest for efficient irrigation application technologies. Mobile drip irrigation (MDI) which integrates drip line onto a mechanical irrigation system such as a center pivot has attracted attention lately. The concept is not new but with some tweaks from the previous design and the affordability of new materials (e.g. pressure compensating emitters on the drip line), MDI is back in the market. By applying water along crop rows, it hypothesized that MDI could eliminate water losses due to spray droplet evaporation, wind drift, and reduce soil evaporation due to limited surface wetting especially before canopy closure. However, there were questions raised, particularly during the 2015 Southwest Research-Extension Center Advisory Committee meeting in Garden City, KS, about the use of MDI as it relates to ease of conversion, effect of friction on longevity of the dripline, emitter clogging, rodent damage, and agrochemical application. The SWREC Advisory Committee is composed of crop consultants, one farmer from every county in southwest Kansas, and agriculture and natural resource county extension agents in southwest Kansas. This group was very supportive of testing this technology side by side with existing older technology.

Experimental Procedures
The experimental design was randomized complete block with four replications (each center pivot span was a replication having MDI and LESA [spray nozzles]). Mobile drip irrigation and in-canopy spray nozzles were compared at high (600 gpm) and low (300 gpm) well capacities to mimic a range of pumping capacities experienced by producers (Figure 1). Nozzle performance was evaluated using the Spot-on device ( Figure 2). By applying water along crop rows, it was hypothesized that MDI could reduce soil water evaporation due to reduced surface wetting. Soil water evaporation was measured using 4-inch mini-lysimeters placed between corn rows (Figure 3) in the MDI and LESA research plots. The effect of a 60-inch lateral spacing on soil water redistribution was measured using neutron attenuation to a depth of 8 feet in a transect of five neutron probe access tubes (Figure 4). Corn yield was determined from harvesting two 40-foot corn rows in the center of each plot. Seasonal crop water use was determined from a soil water balance and used in calculating water use efficiency (WUE, also known as water productivity).

Results and Discussion
Measured mean flow rate, q ̅ , for MDI was 1.03±0.08 m 3 /s, which is equivalent to the manufacturer's value (3.7 L/h), indicating that the driplines were functioning as designed. The uniformity coefficient, UC, of MDI was 93.8%. The uniformity coefficient, CU H , for LESA was 83.8%, which was less than that of MDI by 8.9%. Measured and design nozzle flow rates for each span are shown in Table 2, which generally implies the system was uniformly applying water and was performing according to design.
Results indicate that soil water evaporation was lower under MDI compared to LESA on average by 35% ( Figure 5). Soil water was greatest at the mid-point between two drip line laterals spaced 60 inches apart at a depth of approximately 20-24 inches ( Figure 6).
These results indicate that drip line spacing of 60 inches is adequate for silt loam soils of southwest Kansas. The effect of irrigation application method (MDI versus spray nozzles [LESA]) on yield at a high (600 gpm) and low (300 gpm) well capacities was not statistically significant at the 5% level (Figures 8 and 10). For the 600 and 300 gpm studies, the P-values were P = 0.37 and 0.67, respectively. The effect of application method on water productivity and irrigation water use efficiency was also not significant at high and low well capacities (Figures 9 and 11). The lack of significant differences in yield could be attributed to the high rainfall received during the 2015 growing season (18 inches from May to September). Figure 7 shows the 2015 growing season rainfall in comparison to long-term averages. However, it is worth noting that the effect of application method on end-of-season soil water was statistically significant under low well capacity (300 gpm). Plots with mobile drip irrigation have more end-season soil water compared to spray nozzles ( Figure 13).
Based on the initial two years of data, it appears that there is lower soil water evaporation under MDI compared to LESA (in-canopy spray nozzles). The spacing of 60 inches also appears adequate for MDI on silt loam soils. Results have shown that there is no significant difference in yield during the two years of corn growing seasons. Accordingly, there was no significant difference in water productivity and irrigation water use efficiency at the same well capacity between the application technologies, but water use efficiency (WUE) was higher at low well capacity (300 gpm) compared to WUE at 600 gpm. It was interesting to note that the end-of-season soil water was significantly higher under MDI for low well capacity (300 gpm) for 2015, but this was not evident in 2016.

Introduction
Annually there are approximately 35,000,000 acres of hay and haylage harvested in the U.S. for a total of 96,000,000 dry matter tons of production. Yields in Kansas averaged 2.77 tons of dry matter per acre. Of this total, about 13,600,000 acres were alfalfa, which averaged 3.76 dry matter tons per acre, and all other crops averaged 2.13 dry matter tons/a.
In Kansas, there were 2,400,000 acres of hay and haylage harvested with an average yield of 2.24 dry matter tons per acre. Of this total, 650,000 acres were alfalfa with an average yield of 3.72 dry matter tons per acre, and 1,770,000 acres were crops other than alfalfa with an average yield of 1.69 dry matter tons/a. Kansas ranked 6th in the U.S. for hay and haylage production, which largely supports the state dairy (ranked 19th in the U.S. and valued at $483,000,000) and cattle (feedlot, background, and cow/calf) industries (ranked second in the U.S. and valued at $10,200,000,000). Dairy and beef cattle represented 58% of the total agricultural product of Kansas. Hay and grain commodities that support these two industries are critical for the state.

Study Objectives
The objectives of the Kansas Summer Annual Forage Variety Trial are to evaluate the performance of released and experimental varieties, determine where these varieties are best adapted, and increase the visibility of summer annual forages in Kansas. Breeders, marketers, and producers use data collected from the trials to make informed variety selections. The Summer Annual Forage Trial is planted at locations across Kansas based on the interest of those entering varieties into the test.

Procedures
The Summer Annual Forage Variety Test was conducted near Garden City, Hays, and Scandia, KS. All of the sites evaluated hay and silage entries. Companies were able to enter varieties into any possible combinations of research sites, so not all sites had all varieties. In the hay test, there were 23 entries at Garden City, 15 at Hays, 9 at Mound Valley, and 11 at Scandia. In the silage test, there were 33 entries at Garden City, 29 at Hays, and 25 at Scandia (Table 1). Across the sites, a total of 77 hay varieties and 87 silage varieties were evaluated. Information on the varieties is shown in Tables 2 and 3.
Management guidelines were provided to cooperators; however, previous growing experience influenced final management decisions. All trials were planted in small research plots (approximately 225 ft 2 ) with three replications. Cultural practices (Table 4), growing season temperature, and precipitation (Figures 1-4) are provided for each site. Results are listed alphabetically by seed supplier. Forage samples were dried, ground, and analyzed for nutrient contents using NIR (near infrared reflectance) by SDK Laboratories in Hutchinson, KS. Nutrient contents measured were acid detergent fiber (ADF), neutral detergent fiber (NDF), in vitro true dry matter digestibility after 48 hours (IVTDMD@48hr), lignin, % of NDF digestible after 48 hours (NDFD@48hr), nitrogen free NDF (NDFn), net energy for gain (NEG), net energy for lactation (NEL), net energy for maintenance (NEM), non-fibrous carbohydrates (NFC), crude protein, relative forage quality (RFQ), total digestible nutrients (TDN), and starch (silage only).

Growing Conditions
Temperature and precipitation (Figures 1-4) for each site is shown. Thick black lines on the temperature graphs represent long-term average high and low temperatures (°F) for the location. The upper thin line represents actual daily high temperatures, and the lower thin line represents actual daily low temperatures. On the precipitation graph, the line labeled "normal" represents long-term average precipitation , and the line labeled "2018" represents actual precipitation.
In general, the 2018 growing season saw near normal temperatures, dry spring conditions, coupled with above average moisture during the remainder of the growing season. Garden City and Hays ended the growing season with twice the normal accumulative precipitation, and Scandia ended with near normal precipitation.

Results and Discussion
Since all entries were not evaluated across all sites, data were analyzed by location. All locations had a control entry of Rox Orange (Waconia), Sumac, and a mixture of both Rox Orange and Sumac (mixed) for the hay test, and a control entry of Kansas Orange for the silage test.

Hay Test
At Garden City, ADV S6504, AS6402, Nutrimaxx II BMR, and Super Sugar DM were in the top LSD (least significant difference at P ≤ 0.05) group in the first cutting (  (Table 6). There was no second cutting due to little regrowth caused by soil water ponding and frost in early October.
At Scandia, F75FS13, Rox Orange, ADV S6504, AS6402, Fullgraze II, Bruiser BMR, Nutri King BMR, Super Sugar DM, Sweet Forever BMR, and Sweet Six BMR were in the top LSD group in the first cutting (Table 7). There was no second cutting due to little regrowth caused by soil water ponding and frost in early October.
At Scandia, ADV XF033 and Super Sile 30 were in the top LSD group for silage (Table 10).

Recommendation
Inestimable differences in soil type, weather, and environmental conditions play a part in increasing experimental error, therefore one should use more than one location and one year of data to make an informed variety selection decision. Please refer to previous years' forage reports to see how a variety performed across years.

Acknowledgments
This work was funded in part by the Kansas Agricultural Experiment Station and seed suppliers. Sincere appreciation is expressed to all participating researchers and seed suppliers who have a vested interest in expanding and promoting annual forage production in the U.S.                   Values in bold are in the top LSD group. Acid detergent fiber (ADF), neutral detergent fiber (NDF), in vitro true dry matter digestibility after 48 hours (IVTDMD@48hr), % of NDF digestible after 48 hours (NDFD@48hr), nitrogen free NDF (NDFn), net energy for gain (NEG), net energy for lactation (NEL), net energy for maintenance (NEM), non-fibrous carbohydrates (NFC), relative forage quality (RFQ), total digestible nutrients (TDN).   Values in bold are in the top LSD group. Acid detergent fiber (ADF), neutral detergent fiber (NDF), in vitro true dry matter digestibility after 48 hours (IVTDMD@48hr), % of NDF digestible after 48 hours (NDFD@48hr), nitrogen free NDF (NDFn), net energy for gain (NEG), net energy for lactation (NEL), net energy for maintenance (NEM), non-fibrous carbohydrates (NFC), relative forage quality (RFQ), total digestible nutrients (TDN).   Values in bold are in the top LSD group. Acid detergent fiber (ADF), neutral detergent fiber (NDF), in vitro true dry matter digestibility after 48 hours (IVTDMD@48hr), % of NDF digestible after 48 hours (NDFD@48hr), nitrogen free NDF (NDFn), net energy for gain (NEG), net energy for lactation (NEL), net energy for maintenance (NEM), non-fibrous carbohydrates (NFC), relative forage quality (RFQ), total digestible nutrients (TDN).

Introduction
This study was initiated in 1961 to determine responses of continuous corn and grain sorghum grown under flood irrigation to N, P, and potassium (K) fertilization. The study is conducted on a Ulysses silt loam soil with an inherently high K content. No yield benefit to corn from K fertilization was observed in 30 years, and soil K levels remained high, so the K treatment was discontinued in 1992 and replaced with a higher P rate.

Procedures
This field study is conducted at the Tribune Unit of the Kansas State University Southwest Research-Extension Center. Fertilizer treatments initiated in 1961 were N rates of 0, 40, 80, 120, 160, and 200 lb/a without P and K; with 40 lb/a P 2 O 5 and 0 K; and with 40 lb/a P 2 O 5 and 40 lb/a K 2 O. The treatments were changed in 1992; the K variable was replaced by a higher rate of P (80 lb/a P 2 O 5 ). All fertilizers were broadcast by hand in the spring and incorporated before planting. The soil is a Ulysses silt loam. The crops. The corn is irrigated to minimize water stress. Sprinkler irrigation has been used since 2001. The center two rows of each plot are machine harvested after physiological maturity. Grain yields are adjusted to 15.5% moisture. Grain samples were collected at harvest, dried, ground, and analyzed for N and P concentrations. Grain N and P content (lb/bu) and removal (lb/a) were calculated. Apparent fertilizer N recovery in the grain (AFNR g ) was calculated as N uptake in treatments receiving N fertilizer minus N uptake in the unfertilized control divided by N rate. The same approach was used to calculate apparent fertilizer P recovery in the grain (AFPR g ). Grasshoppers were treated via aerial application of insecticide.

Results
Corn yields in 2018 were 15% greater than the 10-year average (Table 1). Nitrogen alone increased yields 76 bu/a, whereas P alone increased yields 17 bu/a. However, N and P applied together increased corn yields up to 169 bu/a. Maximum yield was obtained with 160 lb/a N with 80 lb/a P 2 O 5 . Corn yields in 2018 (averaged across all N rates) were 9 bu/a greater with 80 than with 40 lb/a P 2 O 5 .
The 10-year average grain N concentration (%) increased with N rates but tended to decrease when P was also applied, presumably because of higher grain yields diluting N content (Table 2). Grain N content reached a maximum of 0.6 lb/bu. Nitrogen removal (lb/a) was greater at the higher yield levels. Maximum N removal (lb/a) was attained with 200 lb N and 80 lb P 2 O 5 /a. At the highest N and P rate, AFNR g was 43% and AFPR g was 62%. Similar to N, average P concentration increased with increased P rates but decreased with higher N rates. Grain P content (lb/bu) of approximately 0.15 lb P/ bu (0.34 lb P 2 O 5 /bu) was greater at the highest P rate with low N rates. Grain P removal averaged 27 lb P/a at the highest yields.

Introduction
This study was initiated in 1961 to determine responses of continuous grain sorghum grown under flood irrigation to N, P, and K fertilization. The study is conducted on a Ulysses silt loam soil with an inherently high K content. The irrigation system was changed from flood to sprinkler in 2001.

Procedures
This field study is conducted at the Tribune Unit of the Kansas State University Southwest Research-Extension Center. Fertilizer treatments initiated in 1961 are N rates of 0, 40, 80, 120, 160, and 200 lb/a N without P and K; with 40 lb/a P 2 O 5 and zero K; and with 40 lb/a P 2 O 5 and 40 lb/a K 2 O. All fertilizers are broadcast by hand in the spring and incorporated before planting. The soil is a Ulysses silt loam. Grain sorghum (Pioneer 85G46 in 2009-2011, Pioneer 84G62 in 2012-2014, Pioneer 86G32 in 2015, Pioneer 84G62 in 2016-2017, and Pioneer 85P44 in 2018 was planted in late May or early June. Irrigation is used to minimize water stress. Sprinkler irrigation has been used since 2001. The center two rows of each plot are machine harvested after physiological maturity. Grain yields are adjusted to 12.5% moisture. Grain samples were collected at harvest, dried, ground, and analyzed for N, P, and K concentrations. Grain N, P, and K content (lb/bu) and removal (lb/a) were calculated. Apparent fertilizer N recovery in the grain (AFNR g ) was calculated as N uptake in treatments receiving N fertilizer minus N uptake in the unfertilized control divided by N rate. The same approach was used to calculate apparent fertilizer P recovery in the grain (AFPR g ) and apparent fertilizer K recovery (AFKR g ).

Results
Grain sorghum yields in 2018 were 5% lower than the 10-year average (Table 1). Nitrogen alone increased yields 44 bu/a while P alone increased yields less than 10 bu/a. However, N and P applied together increased yields up to 67 bu/a. Averaged across the past 10 years, N and P applied together increased yields up to 75 bu/a. In 2018, 40 lb/a N (with P) produced about 88% of maximum yield, which is greater than the 10-year average of 85%. The 10-year average for 80 lb/a N (with P) and 120 lb/a N (with P) was 94 and 95% of maximum yield, respectively. Sorghum yields were not affected by K fertilization, which has been the case throughout the study period.
The 10-year average grain N concentration (%) increased with N rates but tended to decrease when P was also applied, presumably because of higher grain yields diluting N content (Table 2). Grain N content reached a maximum of ~0.7 lb/bu. Maximum N removal (lb/a) was obtained with 160 lb of N/a or greater with P. Similar to N, the average P concentration increased with P application but decreased with higher N rates. Grain P content (lb/bu) of ~0.15 lb P/bu (0.34 lb P 2 O 5 /bu) was similar for all N rates when P was applied. Grain P removal was similar for all N rates of 40 lb/a or greater with P removal ranging from 19 to 22 lb/a. Average K concentration (%) and content (lb/bu) tended to decrease with increased N rates. Similar to P, K removal was similar for all N rates of 40 lb/a or greater plus K ranging from 22 to 26 lb/a. At the highest N, P, and K rate, apparent fertilizer recovery in the grain was 31% for N, 65% for P, and 38% for K.     Table 2. Nitrogen (N), phosphorus (P), and potassium (K) fertilizers on grain N, P, and K content of irrigated grain sorghum, Tribune, KS, 2009KS, -2018 Fertilizer ---*AFNR g = Apparent fertilizer N recovery (grain). AFPR g = Apparent fertilizer P recovery (grain). AFKR g = Apparent fertilizer K recovery (grain).

Introduction
Enlist Duo was first approved for use in the United States in 2014 on herbicide-resistant corn and soybean, and has since been approved for use on herbicide-resistant cotton. Enlist Duo combines two common herbicides, glyphosate and 2,4-D, to help manage herbicide-resistant weed species. The 2,4-D component is a choline salt formulation, which minimizes the drift and volatilization potential compared to the ester and amine formulations. The objective of this study was to compare Enlist Duo at two rates and two application timings for weed control in irrigated corn.

Experimental Procedures
An experiment at the Kansas State University Southwest Research-Extension Center near Garden City, KS, evaluated the premix of Enlist Duo (2,4-D/glyphosate) at two rates and two application timings in corn. The premix was applied at 3.5 or 4.67 pt/a when corn was at the 4 leaf stage (V4) following preemergence application of SureStart II (acetochlor/flumetsulam/clopyralid) at 2.0 pt/a. Enlist Duo was also applied at the same rates early postemergence when corn was in the 2 leaf stage (V2) and included the treatment of SureStart II at 2.0 pt/a. All treatments were applied using a tractor-mounted, compressed-CO 2 sprayer delivering 19.4 GPA at 30 psi and 4.1 mph. Application, environmental, crop, and weed information are shown in Table 1. Natural weed populations were supplemented by overseeding the experimental area with quinoa (to simulate common lambsquarters) and domesticated sunflower (to simulate common sunflower). Plots were 10 × 32 feet and arranged in a randomized complete block with four replications. Soil was a Beeler silt loam with 2.4% organic matter and pH 7.6. Visual weed control was determined on June 11 and August 2, 2018, which was 12 days after the V2 applications (12 DA-B) and 51 days after the V4 applications (51 DA-C), respectively. Grain yields were determined October 5, 2018, by mechanically harvesting the center two rows of each plot and adjusting weights to 15.5% moisture.

Results and Discussion
Control of Palmer amaranth, Russian thistle, common sunflower, and quinoa was 90% or more with all herbicides at 12 DA-B and 51 DA-C, and did not differ between treatments (data not shown). Kochia control at 12 DA-B was 14% greater when Enlist Duo was included with SureStart II at the V2 stage compared to SureStart II alone preemergence (Table 2). However, by 51 DA-C, kochia control was best when Enlist Duo was applied at the V4 stage, and no differences occurred between rates for kochia control. Similarly, Enlist Duo applied at the V2 stage increased johnsongrass control compared to SureStart II alone preemergence at 12 DA-B, but johnsongrass control was best at 51 DA-C when Enlist Duo was applied at the V4 stage. Increasing the Enlist Duo rate from 3.5-4.67 pt/a did not improve johnsongrass control with either application timing at 51 DA-C. Corn receiving herbicide treatment at the V2 stage yielded 81-84 bu/a more grain than untreated corn, whereas corn treated at the V4 stage yielded 114-118 bu/a more grain than the control plots. Grain yields did not differ between Enlist Duo rates within applications timings.
Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer.

Introduction
Nicosulfuron is an acetolactase synthase inhibiting (ALS) herbicide that has long been used to control grass weeds in corn under the brand name Accent. Many of the ALS herbicides severely injure or kill sorghum species, including shattercane, johnsongrass, and grain sorghum. The evolution of shattercane with resistance to ALS herbicides allowed for development of commercial sorghum hybrids with this same resistance and the potential to use ALS herbicides to control nonresistant weed species in sorghum. Therefore, the objective of this study was to evaluate the ALS herbicides Zest (nicosulfuron), Resolve (rimsulfuron), and Harmony GT (thifensulfuron) for efficacy in ALS-resistant grain sorghum.

Experimental Procedures
An experiment conducted at the Kansas State University Southwest Research-Extension Center near Garden City, KS, evaluated nicosulfuron-containing herbicide treatments for efficacy and crop tolerance in ALS-resistant grain sorghum. Herbicides were applied preemergence (PRE), PRE followed by postemergence (POST), or early postemergence (EPOST). A tractor-mounted, compressed-CO 2 sprayer delivering 19.4 GPA at 3.0 mph and 30 psi was used to apply all herbicides. Application, environmental, crop, and weed information are given in Table 1. Natural weed populations were supplemented by overseeding the experimental area with quinoa (to simulate common lambsquarters). Soil was a Ulysses silt loam containing 3.4% organic matter and pH 7.9. Plots were 10 × 32 feet and arranged in a randomized complete block with four replications. Weed control was visually determined on July 16 and August 16, 2018, which were 6 and 37 days after the POST treatments (DA-C), respectively. Grain sorghum necrosis was determined on July 6 and July 16, 2018, which was 3 days after the EPOST treatments (DA-B) and 6 DA-C, respectively. Grain yields were determined on October 29, 2018, by mechanically harvesting the center two rows of each plot and adjusting weights to 14.0% moisture.

Results and Discussion
All herbicides controlled kochia 88-100% and quinoa 98-100% regardless of evaluation date, and did not differ between herbicides (data not shown). Palmer amaranth control was best when Cinch ATZ (S-metolachlor/atrazine) was applied PRE alone, Cinch ATZ PRE was followed by Zest POST, and when Cinch (S-metolachlor) plus Resolve and Harmony GT PRE was followed by Zest POST (Table 2). At 37 DA-C, puncturevine control exceeded 90% with all herbicides except Cinch ATZ alone PRE or Resolve plus Harmony GT and atrazine PRE followed by Zest and atrazine POST. All herbicide combinations that included Zest either EPOST or POST controlled green foxtail 93% or more at 37 DA-C. Grain sorghum necrosis at 3 DA-B was 18% with the EPOST treatment of Cinch ATZ, Zest, and atrazine, but decreased to 6% by 6 DA-C (Table 3). Necrosis was also less than 10% with the other Zest treatments at 6 DA-C. Grain yields increased by 22-43 bu/a with most herbicide treatments compared to the nontreated controls (Table 3). However, sorghum receiving Resolve plus Harmony GT and atrazine PRE followed by Zest and atrazine POST, yielded similarly to the nontreated controls.
Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer.

Introduction
Following the discovery of a wild sorghum biotype with resistance to acetolactase synthase (ALS)-inhibiting herbicides, the development of commercial grain sorghum hybrids with ALS resistance began. Accent (nicosulfuron) is an ALS-inhibiting herbicide commonly used in corn to control grasses and small broadleaf weeds. Prior to the development of ALS-tolerant sorghum, nicosulfuron would have severely injured the crop. However, the use of ALS-inhibiting herbicides may potentially help sorghum producers manage grass weeds that could otherwise go uncontrolled. The objective of this study was to compare two ALS-tolerant grain sorghum hybrids for efficacy and crop tolerance to Zest (nicosulfuron).

Experimental Procedures
Two experiments were conducted at the Kansas State University Southwest Research-Extension Center near Garden City, KS, in 2018 to determine the efficacy of and tolerance to nicosulfuron application timings in two ALS-tolerant sorghum hybrids. One study was planted to sorghum hybrid XSA5527 (Hybrid 1) while the second study was planted to hybrid XSA4820 (Hybrid 2). All herbicide treatments were applied using a tractor-mounted, compressed CO 2 sprayer delivering 19.4 GPA at 4.1 mph and 30 psi. Application, environmental, crop, and weed information is given in Table 1. Natural weed populations were supplemented by overseeding the experimental area with quinoa (to simulate common lambsquarters) and domesticated sunflower (to simulate common sunflower). Soil was a Ulysses silt loam with 3.4% organic matter and pH of 7.9 for both experiments. Grain sorghum necrosis was evaluated visually on July 16, 2018, and stunting was visually estimated on August 16, 2018. These dates were 6 and 37 days after the final herbicide applications (DA-C), respectively. Visual weed control was determined on August 16, 2018 (37 DA-C) as well. Grain yields were measured on October 29, 2018, by mechanically harvesting the center two rows of each plot and adjusting weights to 14.0% moisture.

Results and Discussion
Trends for weed control and crop response were similar between experiments. Kochia, quinoa, and common sunflower control was 90-100% and did not differ between herbicides (data not shown), nor did velvetleaf control (88-99%). Palmer amaranth control was best when Cinch ATZ (S-metolachlor/atrazine) was applied PRE or when followed by Zest plus atrazine POST (Table 2). Zest plus atrazine applied EPOST controlled Palmer amaranth only 50%. Cinch ATZ applied alone PRE provided no more than 78% puncturevine and green foxtail control, whereas any Zest treatment applied EPOST or POST controlled these weeds 90-100%. Minor sorghum necrosis (6 DA-C) and stunting (37 DA-C) occurred on each hybrid with POST treatments of Zest plus atrazine (Table 3). Yields were best when Cinch ATZ was applied alone PRE or followed by Zest plus atrazine POST (Table 3). Sorghum receiving Zest plus atrazine EPOST yielded no more than nontreated sorghum, and this was likely due to the poor Palmer amaranth control with this treatment.
Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer.

Introduction
Terbuthylazine is a triazine herbicide, similar to atrazine, which controls susceptible weeds by inhibiting photosynthesis. It has become a widely used herbicide in countries that restrict atrazine use, such as those in the European Union. Terbuthylazine is currently not marketed in the United States as an agricultural herbicide, but may have utility in corn and sorghum growing regions. The objective of this study was to compare terbuthylazine and atrazine rates alone and in combination with other herbicides in corn.

Experimental Procedures
An experiment conducted at the Kansas State University Southwest Research-Extension Center near Garden City, KS, compared terbuthylazine and atrazine rates applied preemergence for weed control in corn. Herbicides were applied using a tractor-mounted, compressed CO 2 sprayer delivering 19.4 GPA at 4.1 mph and 30 psi. All preemergence (PRE) herbicides were followed by glyphosate at 22 oz/a plus ammonium sulfate at 1.0% late postemergence (POST). Application, environmental, weeds, and crop information is given in Table 1. Natural weed populations were supplemented by overseeding the experimental area with domesticated sunflower (to simulate common sunflower) and domesticated crabgrass (to simulate large crabgrass). Plots were 10 × 35 feet and arranged in a randomized complete block design replicated four times. Soil was a Beeler silt loam with 2.4% organic matter and pH of 7.6. Residual weed control of the preemergence treatments was visually estimated on June 13, 2018, which was 40 days after the preemergence applications (40 DA-A). Late season weed control following the postemergence treatments was determined on August 13, 2018, 56 days after the glyphosate application (56 DA-B). Yields were determined on October 4, 2018, by me-chanically harvesting the center two rows of each plot and adjusting weights to 15.5% moisture.

Results and Discussion
No differences between herbicides occurred for Russian thistle control (90% or more) and common sunflower (93% or more) regardless of rating date (data not shown). Only the treatments containing mesotrione controlled green foxtail more than 88% at 40 DA-A, but foxtail control exceeded 97% regardless of treatment by 56 DA-B (data not shown). Kochia control at 40 DA-A exceeded 90% with all herbicides except terbuthylazine at 22 oz/a and atrazine at 16 oz/a (Table 2). By 56 DA-B, terbuthylazine alone at 15.5, 23, 31 oz/a and atrazine at any rate alone provided less kochia control than treatments with the best kochia control (100%). Terbuthylazine at 15.5 oz/a alone and atrazine at 24 oz/a alone controlled Palmer amaranth 83-85% at 40 DA-A. However, only plots receiving atrazine alone at 16 or 32 oz/a PRE provided less than 90% Palmer amaranth control at 56 DA-B. Crabgrass control at 40 DA-A was 85% or less with terbuthylazine at 15.5, 23, and 31 oz/a and atrazine at any rate alone PRE, and crabgrass control remained less than 85% for these treatments at 56 DA-B. Differences among herbicides in weed control did not translate into grain yield differences in this study. Herbicide-treated plots yielded 160-171 bu/a, and did not differ from the nontreated plots (148 bu/a) (data not shown).
Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer.

Results and Discussion
All herbicides controlled Russian thistle 93-100%, green foxtail 95-100%, common sunflower 96-100%, and quinoa 100% regardless of evaluation date, and did not differ between treatments (data not shown). Likewise, all PRE herbicides controlled kochia and Palmer amaranth similarly at 31 DA-A (Table 2). Kochia control was slightly less with Verdict (saflufenacil/dimethenamid) and atrazine PRE followed by Roundup PowerMax and atrazine POST compared to other treatments at 43 DA-B. Palmer amaranth control at 43 DA-B was 96% or more with all herbicides, except when Verdict plus atrazine PRE was followed by Roundup PowerMax with atrazine or Liberty with atrazine POST. Preemergence herbicides controlled crabgrass by 95% or more at 31 DA-A, and only the treatments of Verdict plus atrazine PRE followed by Roundup PowerMax with atrazine or Liberty with atrazine POST provided less than 94% crabgrass control at 43 DA-B. All herbicide-treated corn yielded 56-79 bu/a more grain than nontreated corn (Table 2), and yield was greatest from corn receiving Acuron PRE followed by Liberty plus atrazine POST (194 bu/a).
Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer.       of treatment by 55 DA-C. All PRE herbicides controlled kochia 100%, Russian thistle 95-100%, and green foxtail 85-100% at 21 DA-A (Table 2). When Halex GT (S-metolachlor/glyphosate/mesotrione) was applied alone EPOST, kochia, Russian thistle, and green foxtail control was 91, 86, and 89%, respectively, at 55 DA-C. This treatment also provided the least Palmer amaranth control at 7 and 55 DA-C (94 and 83%, respectively). Herbicide-treated corn yielded 21-47 bu/a more grain than the nontreated controls (Table 2), except when Halex GT alone was applied EPOST.
Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer.

Introduction
Glyphosate has long been an important herbicide in fallow and row crops. However, in 2007, glyphosate resistance in kochia was first confirmed in Kansas, and has subsequently spread to at least ten states in the United States and three Canadian provinces. Consequently, new or different herbicide modes of action are needed to combat herbicide resistance. The objective of this study was to compare Vida alone and in tank mixtures to control kochia in fallow.

Experimental Procedures
An experiment was conducted at the Kansas State University Southwest Research-Extension Center near Garden City, KS, to compare Vida (pyraflufen) alone and in tank mixtures to standard treatments for postemergence kochia control in fallow. Herbicides were applied using a tractor-mounted, compressed CO 2 sprayer delivering 19.4 GPA at 30 psi and 4.1 mph. Application, environmental, and weed information are shown in Table 1. Plots were 10 × 32 feet and arranged in a randomized complete block design with four replications. Soil was a Ulysses silt loam with 3.4% organic matter and pH of 7.9. Kochia control was visually estimated on June 22, July 3, and July 16, 2018. These dates were 4, 15, and 28 days after treatment (DAT), respectively.

Results and Discussion
Vida alone provided no more than 33% kochia control regardless of rating date (Table 2), and was no better than glyphosate, 2,4-D amine, or dicamba alone. The tank mixture of Vida plus Gramoxone (paraquat) and Spartan (sulfentrazone) provided the best kochia control at 4, 15, and 28 DAT (58, 97, and 97%, respectively). Tank mixing of these three herbicides increased kochia control 11 to 74% compared to the individual herbicides applied alone. Vida plus Gramoxone and Spartan was the only treatment to control kochia more than 95% at 28 DAT.
Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned. Persons using such products assume responsibility for their use in accordance with current label directions of the manufacturer.

Introduction
The herbicide premixes Acuron (S-metolachlor/atrazine/mesotrione/bicyclopyrone) and SureStart II (acetochlor/flumetsulam/clopyralid) are commonly used in corn, but not registered for use in grain sorghum. Valor (flumioxazin) is also used in corn, but can only be applied 30 days preplant to sorghum and only if sufficient moisture is received prior to planting. Injury concerns with these herbicides have kept them from being labeled in sorghum less than 30 days prior to planting; however, data are limited on their use. The objective of this study was to compare these herbicides to standard treatments for preplant efficacy and crop response in grain sorghum.

Experimental Procedures
An experiment was conducted at the Kansas State University Southwest Research-Extension Center near Garden City, KS, to compare various herbicides for residual weed control in sorghum. All herbicides were applied 14 days prior to sorghum planting using a tractor-mounted, compressed CO 2 sprayer delivering 19.4 GPA at 30 psi and 4.1 mph. Application and environmental information is shown in Table 1. Plots were 10 × 35 feet and arranged in a randomized complete block with four replications. Soil was a Ulysses silt loam with pH 7.9, containing 3.4% organic matter. Visual weed control was evaluated on June 27 and August 14, 2018. These dates were 26 and 74 days after sorghum planting (DAP), respectively. Sorghum yields were determined on October 29, 2018, by mechanically harvesting the middle two rows of each plot and adjusting grain weights to 14% moisture.

Results and Discussion
Valor at 1 and 2 oz/a were the only treatments to control buffalobur less than 90% at 26 DAP (data not shown). However, no differences between herbicides occurred for buffalobur control at 74 DAP (83-100%). All herbicides controlled velvetleaf by 95% or more at 26 and 74 DAP (data not shown). SureStart II and Acuron generally provided the best control of Palmer amaranth, puncturevine, and green foxtail throughout the season (Table 2). Bicep Lite II Magnum (S-metolachlor/atrazine), Lumax EZ (S-meto-

Introduction
Early season weed control in grain sorghum is essential to preserve crop yield. With limited choices for postemergence weed control, especially grass control, an effective preemergence herbicide is vital to allow the sorghum time to emerge and become competitive. The objective of this study was to compare various herbicides for preemergence efficacy in grain sorghum.

Experimental Procedures
An experiment conducted at the Kansas State University Southwest Research-Extension Center near Garden City, KS, evaluated various preemergence herbicide treatments for residual efficacy in grain sorghum. All herbicides were applied the day after sorghum planting using a tractor-mounted, compressed CO 2 sprayer delivering 19.4 GPA at 30 psi and 4.2 mph. Application and environmental information is shown in Table 1. To supplement natural weed populations, the experimental area was overseeded with quinoa to simulate common lambsquarters. Plots were 10 × 35 feet and arranged in a randomized complete block replicated four times. Soil was Ulysses silt loam with pH 7.9 and 3.4% organic matter. Visual weed control was determined on June 27 and August 15, 2018, which corresponded to 33 and 82 days after treatment (DAT). Sorghum yields were determined October 29, 2018, by mechanically harvesting the center two rows of each plot and adjusting grain weights to 14.0% moisture.

Results and Discussion
Velvetleaf control was 95-100% and 88-100% at 33 and 82 DAT, respectively, and did not differ among herbicides (data not shown). Bicep Lite II Magnum (S-metolachlor/ atrazine) at 1.5 qt/a and Warrant (acetochlor) at 2.0 qt/a controlled quinoa 93 and 88% at 33 DAT, which was slightly less than herbicides that provided 100% control (data not shown). However, by 82 DAT, quinoa control did not differ between treatments. Palmer amaranth at 33 DAT was more than 88% controlled with Degree Xtra (acetochlor/atrazine), Halex GT (S-metolachlor/mesotrione/glyphosate) plus atrazine, and Callisto (mesotrione) plus atrazine plus Dual Magnum (S-metolachlor) ( Table 2). By 82 DAT, only Halex GT plus atrazine and Callisto plus atrazine and Dual Magnum controlled Palmer amaranth 85% or more. These three-way mixes, along with Verdict (saflufenacil/dimethenamid) plus Outlook (dimethenamid) generally provided the best puncturevine control at 33 and 82 DAT. However, puncturevine control did not exceed 81% with any treatment by 82 DAT. Warrant alone was the only treatment to provided less than 93% kochia control at 33 DAT. At 82 DAT, kochia control was 88% or more with all herbicides except Warrant, Dual Magnum, Stalwart C (metolachlor), and Callisto, each applied alone. Green foxtail control was less than 80% with atrazine alone, Callisto alone, and the tank mixture of Callisto and atrazine early in the season. Foxtail control declined by 82 DAT such that only Verdict plus Outlook and Callisto plus atrazine plus Dual Magnum were the only herbicides to provide 80% or more control. All herbicides except Callisto alone increased sorghum yield compared to the nontreated controls (Table 3). Yields were improved the most when Degree Xtra, Callisto plus atrazine plus Dual Magnum, and Halex GT plus atrazine were applied.
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