Kansas Fertilizer Research 2009

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Introduction
The 2009 edition of the Kansas Fertilizer Research Report of Progress is a compilation of data collected by researchers across Kansas. Information was contributed by faculty and staff from the Department of Agronomy, Kansas agronomy experiment fields, and agricultural research and research-extension centers.

Introduction
Interest in foliar micronutrient applications on soybean has recently increased. Application of these fertilizer products can potentially be combined with routine glyphosate applications, which saves on application costs. However, additional research needs to be done to determine the yield benefits from these micronutrient applications as well as the potential for antagonistic effects of the herbicide on nutrient absorption by the plant. The objective of this study was to determine if soybean responded to foliar applications of Mn and Zn supplied in three different forms. A secondary objective was to determine if application of micronutrient sources in conjunction with glyphosate affected product performance.

Procedures
The study was conducted at the Ashland Bottoms and Rossville agronomy experiment fields near Manhattan and Topeka, KS, respectively. Two studies-full and reducedwere implemented at Rossville. The growing season was very good; it had adequate moisture and cool temperatures. Harvest was delayed, but this did not affect yield. Although irrigation water was available, irrigation was not applied because of frequent rains throughout the summer. Soil analyses for the locations are in Table 1.
Cultural practices for each location are listed in Table 2. All locations were conventionally tilled with 30-in. rows. Plot sizes at each location were 10 ft wide by 30 ft long. Treatments were arranged in a randomized complete block design with four replications (Table 3). For the Ashland Bottoms and Rossville2 studies, treatments were tank mixed with glyphosate unless otherwise noted. Glyphosate was applied 2 days before treatment application at the Rossville1 study. Glyphosate was applied at 0.75 lb ae/a with 1.5% ammonium sulfate. Glucoheptonate micronutrient product was supplied by Brandt Consolidated, Inc., and the phosphate micronutrient product was supplied by Agro-K Corporation.        Introduction Soil properties associated with iron-deficiency chlorosis have been studied for many years. However, it is not yet clear which factors affect iron-deficiency chlorosis. Recent research has shown that iron-deficiency chlorosis may not always occur in a pattern consistent with changes in soil types. Previous studies indicated several soil factors as potential contributors of iron-deficiency chlorosis symptoms including soil pH, carbonates, iron oxide concentration in the soil, DTPA-extractable iron, soil electrical conductivity, and soil water content.
Iron is crucial to the photosynthesis process, and a deficiency creates severe chlorosis. In mild cases, soybeans are stunted and yield is diminished. In severe cases, many chlorotic patches in the field become necrotic and result in plant death. The causes of iron chlorosis are complex, and determining the best management practices to address the problem is not easy. Soybean lines are bred to have varietal resistance to iron chlorosis. Other control practices can include in-field foliar application of iron chelates after chlorosis has appeared. The purpose of this study was to evaluate the effectiveness of different management scenarios in reducing the prevalence of iron chlorosis at four field locations in western Kansas.
Specific objectives for this study were to (1) evaluate the effect of different iron fertilizer application strategies on soybean yield on soils with potential for iron-deficiency chlorosis, (2) determine interactions between soil properties and iron fertilizer applications on soybean yield, and (3) evaluate economic returns due to iron fertilizer applications and varietal resistance selection.

Procedures
This study was initiated in 2009 at the Southwest Research-Extension Center in Garden City, KS, and two locations at cooperator fields in Lane County, KS. The soil in Garden City was a Ulysses silt loam (mesic Aridic Haplustolls) with 2.22% organic matter and pH 8.12. The soybean crop in Garden City was not regularly irrigated and received only 1 acre-inch of water. Soil at the Lane County locations was a Richfield silt loam (mesic Aridic Argiustolls) with 1.87% organic matter and pH 8.23 (Table 1). The Lane County locations received regular irrigation as needed.
Plots were arranged in the field in a randomized complete block design with four replications. Two soybean varieties with different genetic tolerance to iron chlorosis were grown: AG2905 has very good chlorosis tolerance, and AG3205 has low tolerance. Chelated iron (FeEDDHA 6%) was used for seed coating. One of two iron chelates (Fe-EDDHA or Fe-HEDTA) was applied as a foliar treatment at 0.1 lb/a iron at approximately at the 2-to 3-trifoliate growth stage, and a second application was applied approximately 2 to 4 weeks later if deficiency symptoms reappeared. Water used included 17 lb of ammonium sulfate additive per 100 gal of spray solution.
Soil samples from the 0-to 6-and 6-to 12-in. depths were taken from each individual plot and analyzed for routine soil properties. Several measurements were made to document the relative effectiveness of each treatment. Overall established plant population was recorded in July along with the first SPAD meter reading; these measurements were followed by the first foliar application treatment. On August 21, a second SPAD reading was taken before the second foliar application. Total plant height was taken at maturity. Plants were harvested and threshed by hand, and yield was adjusted to 15.5% moisture. Analysis included soil organic matter, soil test phosphorus, soil test potassium, extractable calcium and magnesium, total organic carbon, total nitrogen, soil pH, carbonates, electrical conductivity/soluble salts, and DTPA-extractable iron. Study areas were characterized by soil map units.

Results
At location 1, there were no significant differences in SPAD readings due to variety, seed coating, foliar application, or plant population (Table 2). There was a significant difference in plant height due to seed coating and variety. The AG3205 variety is a taller variety and, on average, is 10 cm taller than AG2905. Coated seeds resulted in a much taller plant height than nontreated seeds. In AG2905, treated seeds resulted in plants that were 15 cm taller than plants from nontreated seeds. In AG3205, treated seeds resulted in plants that were 10 cm taller than plants from nontreated seeds. Seed coating strongly affected total yield for both varieties. Foliar application did not significantly increase any of the crop control parameters.
At location 2, there were no significant differences between the foliar treatments and the control, but seed coating and variety selection affected crop parameters (Table 3). Plants from coated seeds had a significantly higher SPAD reading than plants from nontreated seeds (Table 2). Like location 1, there was a significant difference in height between seed treatments and between varieties. In AG2905, plants from treated seeds were 12 cm taller than plants from nontreated seeds, and in AG3205, plants from treated seeds were 15 cm taller. Seed coating also significantly increased yield. The seed coating increased yield by an average of 18 bu/a in AG2905 and by 11 bu/a in AG3205.
At location 3, plants from nontreated seeds from AG2905 had a higher SPAD reading than plants from treated seeds, but for AG3205, which is the less tolerant variety, the seed coating significantly increased chlorophyll readings (Table 4). Plants of AG2905 were 5 cm shorter than plants of AG3205, which was expected because AG2905 is a shorter variety. Yield for AG3205 was only 5 bu/a greater than that for AG2905. The seed coating decreased yield of AG2905 by 14 bu/a but increased yield of AG3205 by 10 bu/a. This result could be due to a lack of population stand in the south end of the plots, which was damaged by animals. Partial ANOVA across locations is shown in Table 5.

Acknowledgements
This project is funded by the Kansas Soybean Commission.     ------------------------------P > F ------------------------ The purpose of this study was to evaluate the performance of different N fertilizer products, fertilizer additives, and application practices used in Kansas and determine whether specific combinations improved yield and N use efficiency of no-till corn. The long-term goal of the study was to quantify some of these relationships to assist farmers in selecting specific combinations of fertilizer products, additives, and application techniques that could enhance yield and profitability on their farm. In this study, five tools for preventing N loss were examined: (1) fertilizer placement, or putting N below surface residue to reduce ammonia volatilization and/or immobilization; (2) use of the commercial urease inhibitor Agrotain to block the urease hydrolysis reaction that converts urea to ammonia and potentially could reduce ammonia volatilization; (3) use of the commercially available additives Agrotain Plus and Super U, which contain both a urease inhibitor and a nitrification inhibitor to slow the rate of ammonium conversion to nitrate and subsequent denitrification or leaching loss; (4) use of a commercial product, NutriSphere-N, that claims urease and nitrification inhibition; and (5) use of a polyurethane plastic-coated urea (ESN) to delay release of urea fertilizer until the crop can use it more effectively. The ultimate goal of using these practices or products is to increase N uptake by the plant and enhance yield. Several measurements were made to document the relative effectiveness of each treatment. Ear leaves were collected at silking to determine relative N content. Firing ratings (number of green leaves remaining below the ear) were made to evaluate N stress to the plants approximately 10 days after pollination. Whole plant samples were taken to measure plant/stover N content at maturity. Ten plants were selected at random from the plot and cut off at ground level. Ears were removed, remaining vegetative portions of the plants were weighed and chopped, and a subsample was collected to determine N and dry matter content. At Manhattan and Hutchinson, plots were hand harvested, corn was shelled, and samples were collected for grain moisture and grain N content. At the Ottawa location, corn was mechanically harvested. Yield was adjusted to 15.5% moisture.

Results
Results from these experiments are summarized in Tables 2 and 3.
Relatively low levels of N in the ear leaf (less than 2.7% N, which is suggested as critical) suggest the 80 lb/a N application was not adequate at these sites (Table 2). This suboptimal N rate was selected to ensure that differences in efficiencies between products were not masked by overapplication of N. The potential for N loss through ammonia volatilization or immobilization loss of surface-applied N was high at all three sites because of moist soil at the time of application, good drying conditions, and a large amount of crop residue on the soil surface. This is typical of conditions in eastern Kansas most years, especially where corn is grown in rotations that include wheat.
At Manhattan, the broadcast treatment of urea applied at planting performed significantly better than the same treatment applied in winter but was less effective than some of the alternative products, such as ESN applied at planting ( Table 2). Use of urease inhibitors with urea or UAN did not improve performance, though weather conditions were present for ammonia volatilization. Granular urea was more effective than broadcast UAN at Manhattan, likely because the high level of surface residue was capable of immobilizing the uniformly applied UAN. Surface banding did not improve UAN performance, though coulter banding did. The broadcast urea/ESN blend and the urea + Agrotain Plus treatments were the highest yielding at Manhattan. High-intensity rainfall events occurred 30 to 40 days after fertilizer application, which created conditions for denitrification loss. Winter applications of ESN were not as effective as planting time applications of ESN or an ESN/urea blend. NutriSphere-N was not beneficial at this location when added to broadcast or surface-banded UAN.
Results from the Ottawa location are summarized in Table 2. Yields were lower than those at Manhattan, likely a result of delayed planting due to heavy spring rains and significant greensnap of plants that occurred with a thunderstorm shortly after tasseling. Approximately 30% of the plants were lost because of stalk breakage. Potential for N loss due to ammonia volatilization, immobilization, and denitrification was also high. Ear leaf N at Ottawa was well below the 2.7% suggested critical level. Ammonia volatilization was likely high at this site as indicated by the excellent performance of the ammonium nitrate application (nonvolatile N source). Conditions were excellent for N loss from volatilization and denitrification as well as immobilization following N applications. Soil conditions at the time of N application were moist, followed by a 5-day period of no rainfall and high temperatures. In the 3 weeks following fertilization, there were several rainfall events (<1.0 in.) followed by a period of heavy rainfall (>4 in.) that created conditions with potential for denitrification. In general, UAN applications of N seemed to be less effective than urea applications regardless of additive products used. Use of additives increased yields only slightly at Ottawa in 2009. This was likely a result of the high denitrification loss potential over an extended period and the reduced effective plant stand due to greensnap.
Results from Hutchinson are also summarized in Table 2. Yields were good at this location; however, plant stands were variable because of lack of seed closure and affected plant maturity throughout the growing season. Though field variability in stand and denitrification likely were responsible for the differences in yields, the winter-applied urea and ESN were less effective than the spring-applied urea and ESN treatments. No difference among N treatments was observed.
Relative effectiveness of different N treatments are shown in comparison to the standard planting time broadcast application of urea for each location in Figures 1, 2, and 3. The N response curve from broadcast applications of urea is shown for each location. The 60-lb urea application rate and resulting yield is marked with a broken line. The resulting yield from selected other treatments is then shown on the response curve to estimate the amount of urea that would have needed to be applied at planting to obtain similar yields.
Nitrogen use efficiency (NUE), estimated by N recovery, for each site is shown in Table 2. Worldwide, NUE in cereal production is estimated at 35%; In Kansas, an NUE of 50% is used to make fertilizer recommendations. At Manhattan, NUE ranged from a low of 30% to a high of 63%. Practices such as broadcast urea, urea + Super U, Agrotain, Agrotain Plus and use of ESN or a urea/ESN blend all gave NUE >50%, whereas broadcast or surface-banded UAN with or without additives gave NUE <50%.
At Ottawa, N uptake and NUE were extremely low, likely because of the low yield and high N loss potential. Recoveries of N at Hutchinson were intermediate.   Summary Long-term research shows that nitrogen (N) fertilizer is usually needed to optimize production of grain sorghum in Kansas. Grain sorghum is grown under dryland conditions across the state and is typically grown in no-till production systems. These systems leave a large amount of residue on the soil surface, which can lead to ammonia volatilization losses from surface applications of urea-containing fertilizers and immobilization of N fertilizers placed in contact with the residue. Leaching and denitrification can also be a problem on some soils. A project was initiated in 2008 and expanded in 2009 to quantify the effect of a number of commercially available products marketed to enhance N utilization by sorghum. Conditions at the sites used varied widely in 2009.

Introduction
The purpose of this study was to evaluate different N fertilizers, products, and application practices used in Kansas and determine whether specific combinations improved yield and N use efficiency in no-till grain sorghum. The long-term goal of this study is to quantify some of these relationships to assist farmers in selecting specific combinations that could enhance yield and profitability on their farm, under their conditions. In this study, five tools for preventing N loss were examined: (1) fertilizer placement, or placing N in bands on the residue-covered soil surface to reduce immobilization; (2) use of a urease inhibitor (Agrotain) that blocks the urease hydrolysis reaction that converts urea to ammonia and potentially could reduce ammonia volatilization; (3) use of an additive (Agrotain Plus or Super U) that contains both a nitrification inhibitor and a urease inhibitor to slow the rate of ammonium conversion to nitrate and subsequent denitrification or leaching loss; (4) use of a commercial product (NutriSphere-N) that claims both nitrification inhibition and urease inhibition; and (5) use of a polyurethane plastic-coated urea (ESN) to delay release of urea fertilizer until the crop can use it more effectively. The ultimate goal of using these practices or products is to increase N uptake by the plant and enhance yield. Treatments were arranged in the field in a randomized complete block design with four replications. Plot size was four rows (10 ft) wide by 50 ft long. A preemergence herbicide was used at all locations to control weeds. Preplant soil samples were collected from each location to determine nutrient status of the site. Flag leaves were collected at half bloom at all locations except Partridge as a measure of plant N content.

Procedures
The middle two rows of each plot were machine harvested at Ottawa and Tribune. A 17.3-ft segment of the middle two rows of each plot was hand harvested at Manhattan and Partridge. Harvest dates were October 5 at Manhattan, November 6 at Ottawa, November 24 at Partridge, and December 1 at Tribune. Grain samples were collected from each plot for grain moisture and N content. Yields were adjusted to 13% moisture.

Results
Results from these experiments are summarized in Table 1. A significant response to N was obtained in this study at Manhattan, Ottawa, and Tribune. No response to N was seen at Partridge, probably because of the low yields that resulted from a late planting date as well as herbicide damage at emergence. Relatively low levels of N in the flag leaf (less than 2.7% N, which is suggested as critical) were observed at Manhattan and Ottawa, which suggests the 60 lb/a N application was not adequate at these sites. However, increasing the amount of broadcast urea applied at planting did not resolve the issue.
At Manhattan, no significant yield increases over the standard practice of broadcasting granular urea were seen with the use of nitrogen products, except for the use of ESN at both winter and planting time applications. Broadcast and surface-banded UAN treatments were not statistically different; however, the surface-banded UAN + Agrotai Plus and NutriSphere-N treatments were significantly higher than the broadcast UAN + Agrotain Plus or NutriSphere-N treatments.
At Ottawa, winter-applied broadcast ESN yielded significantly higher than winterapplied urea. Yields for the broadcast ESN at planting, broadcast ESN/urea blend, and nonvolatile N treatment of ammonium nitrate were all significantly higher than yields from the 60-lb urea treatment applied at planting.
At Partridge, yields were low, and there were no differences in treatment yields. At the Tribune location, no difference among N treatments was observed.
Figures 1, 2, and 3 demonstrate efficiencies of the N products and application timings compared with the standard treatment of broadcasting urea at planting.
These data clearly show that in conditions where N loss is occurring, such as at Manhattan and Ottawa in 2009, use of products that enhance N use can enhance yield while minimizing total N inputs. Using this type product to address specific concerns or loss mechanisms can be more efficient, and potentially more cost-effective, than simply increasing N application rate.

Summary
This report covers the first year of a multiyear project designed to address issues with potassium (K) fertilization of soybean and rotational crops. During 2009, four field research studies were established, all on fields in which soil test K levels were below the current critical level of 130 ppm. Later soil testing during the growing season revealed that K levels had unexpectedly increased well above the standard critical level. By harvest time, however, the K soil test levels had fallen back down to the range of the initial K baseline, well below the critical level of 130 ppm. Our data, together with data collected by farmers and crop consultants, show significant fluctuation in exchangeable K levels of up to 50% on a yearly and even monthly basis. This raises questions about how reliable lab procedures are in extrapolating exchangeable K.
In a study designed to assess the effect of sample drying and temperature (factors that influence K availability), field-moist samples were collected and prepared for analysis and then air dried and oven dried at 40°C, 60°C, 80°C, and 100°C for various lengths of time. Results showed less than a 10% decrease in exchangeable K due to high-temperature drying ( Figure 1) but a 50% change in exchangeable K in the field over time. Potassium uptake was monitored by using tissue analysis. Results showed that broadcast and high-rate surface-band applications increased K uptake slightly in 2009; the majority of the treatments, including control treatments, were within the normal concentration range of 1.7% to 2.3%, indicating no K deficiencies during late vegetative and early reproductive growth. No clear effects of K fertilization rate or placement on soybean yield were observed. This research will continue in 2010.

Introduction
Within the last decade, K deficiency in soybean has become a tremendous concern in the eastern half of Kansas. The K content of many Kansas soils that had naturally elevated K availability has declined because of continuous cropping and planting high-K-extracting crops such as soybean without replacing the K removed. The more weathered soils in the southeastern part of the state, which have lower cation exchange capacity and exhausted K reserves, are encountering increased occurrence of K deficiency. In addition, the increased popularity of no-till systems has raised additional concerns of vertical stratification and positional unavailability due to dry soil conditions that result in increased K fixation and reduced diffusion rates.
This study was initiated in 2009 to determine the overall impact of K deficiencies on soybean yields and what management practices could be implemented to overcome any adverse effects. A main focus was to determine which fertilizer application methods, including broadcast and surface banding, efficiently corrected the problem.

Procedures
The project was conducted on cooperating farmers' fields in southeast Kansas. Four sites were selected near Hallowell, KS, in Cherokee County. The predominant soil type at all four locations was a Cherokee silt loam with an average K exchangeable level of 145 ppm. Plots were arranged in the field in a randomized complete block design with four replications. Maturity group 5 soybeans were planted on June 25 following the harvest of a wheat crop at a seeding rate of 110,000 seeds/a. Fertilizer was applied shortly after planting on July 1 using KCl as the fertilizer source.
Ten different treatments were applied to double-crop soybean: an unfertilized check; annual broadcast application at the rate recommended by Kansas State University; annual broadcast application of 30 and 60 lb/a K 2 O; biannual broadcast application of 60, 120, and 180 lb/a K 2 O; and biannual surface-band application of 60, 120, and 180 lb/a K 2 O. Surface banding consisted of applying all the KCl in a concentrated band 4 to 5 in. wide immediately adjacent to the crop row.
Measurement of treatment effects included soil sampling every 1 to 2 months to track K levels, leaf K levels at pod set and pod fill, soybean yield, and grain K levels. Residual effects of the biannual applied treatments will be measured by continuing the study for a second year. Similar measurements will be made on the rotational corn crop.

Results
Potassium soil test levels in the field were substantially higher than expected from routine field soil tests conducted in the winter of 2007-2008 (Table 1). All sites showed K levels approximately 50% higher than those in 2007 and well above the accepted critical level of 130 ppm exchangeable K. The fertilizer program practiced by the grower was the traditional K-State nutrient sufficiency program. Therefore, fertilizer added on the basis of the 2007 soil tests would have been substantially less than crop removal and would not explain the significant increases. Sampling through the growing season showed that these high levels remained until mid-October, when soil tests again dropped to levels at or approaching those found in 2007.
Potassium uptake in the leaf was generally high and was significantly increased in many treatments when KCl fertilizer was applied broadcast or surface banded at a higher rate ( Table 2). The relatively high levels found in the leaf tissue are consistent with soil test K levels above the critical level, which were observed throughout the growing season.
No consistent response to K fertilization or placement was observed in the yield data ( Table 3). The SW Brown and SE Brown locations yield data did show some significant differences that we are attributing to harvest lost due to soybean lodging issues rather than to a treatment effect (Table 3).
The significant findings of this first years' data relate to the large change in soil test K levels seen between 2007 and 2009 and at the final sampling in 2009. It will be important to understand the mechanism responsible for these changes and what triggers these changes before routine management recommendations can be developed.

Nitrogen Fertilization of Corn Using Sensor Technology Introduction
This study was initiated in 2007 to determine the effectiveness of active sensor technologies at estimating N needs and response of corn. Sensor technology has been successfully used to make in-season N recommendations for several crops, including winter wheat, grain sorghum, and cotton. However, work with corn has been less successful.

Procedures
The study was conducted at the Kansas River Valley Experiment Field near Rossville, KS, from 2007 to 2009, Southwest Research-Extension Center near Tribune, KS, from 2007 to 2009, and Northwest Research-Extension Center near Colby, KS, from 2008 to 2009. Nitrogen fertilizer treatments at the Colby, Rossville, and Tribune sites consisted of rates of 0, 100, 140, and 180 lb/a N with application timings of all preplant or a split application. In addition, three variable rate treatments developed on the basis of recently developed crop sensor technologies (GreenSeeker; NTech Industries, Ukiah, CA) and/or a chlorophyll meter were used. The Rossville location had additional treatments developed by using the Crop Circle sensor (Holland Scientific, Lincoln, NE) with and without a chlorophyll meter. A total preplant N application of 120 lb/a N was used with these sensor-based treatments, the optical sensors (GreenSeeker and Crop Circle) were used to estimate yield potential at the V8 or V9 growth stage, and additional N was applied accordingly on the basis of the Oklahoma State University sensorbased N-rate calculator for the U.S. Grain Belt.
The chlorophyll meter was used to measure greenness of the plot relative to that of the highest preplant N plots. When the plot of interest had a relative greenness less than 95% or 90% of the reference, an additional 30 or 60 lb/a N, respectively, was applied. All preplant N treatments were applied immediately before planting, whereas side-dress treatments were applied at the V8 or V9 growth stage. All plots received 20 lb/a N as starter applied with the planter and were irrigated as needed. At all locations, a 200 lb/a N preplant treatment served as the reference strip for sensing. Corn was planted in late April or early May with a hybrid adapted to that area. Normalized difference vegetation index was collected with a GreenSeeker sensor at the V9 growth stage.
The center two rows of each plot were harvested after physiological maturity. Grain yield was adjusted to 15.5% moisture.
Additional studies were conducted on farmers' fields near St. Marys, KS. Sensor-based nitrogen treatments were applied near the V16 growth stage with a high-clearance sprayer equipped with GreenSeeker sensors and operated by J.B. Pearl of St. Marys. These fields were split in half with half managed according to the sensor-based treatments and the other half managed by the farmer. Fields were harvested with a combine equipped with yield monitors after physiological maturity.
Data from all experiments were analyzed statistically using SAS version 9.1 and the PROC GLM procedure with an alpha level of 0.05 for all mean separations.

Introduction
Research has shown that N fertilizer is generally needed to optimize corn yields in Kansas, though the optimum rate varies widely across locations and years. Optimum N rates vary for a number of reasons, including crop yield and N uptake, residual N from previous crops present in the soil at planting, variations in organic N mineralized from soil organic matter and crop residue, and N loss during the growing season.
During the past few years, a large amount of corn in the eastern part of Kansas has been deficient in N because of in-season N loss. This study was initiated in 2009 to determine the effectiveness of N application timing on corn grain yields and, in particular, whether corn will respond to late-season N fertilizer applications. Plots were arranged in the field in a randomized complete block design with four replications. The center two rows of each plot were harvested by hand after physiological maturity, and corn was dried and shelled. Grain yield was adjusted to 15.5% moisture.

Procedures
Data were analyzed statistically with SAS version 9.1 and the PROC GLM procedure with an alpha level of 0.05 for all mean separations.

Results
Significant N responses were seen at the Manhattan and Rossville sites, but the farmers' fields did not respond to additional N (Tables 1 and 2). At Manhattan, delaying N fertilization to the V16 growth stage produced higher grain yields than applying N at the V8 growth stage at the two highest N rates. This is likely due to denitrification loss that occurred after the V8 growth stage. Delaying applications an additional 30 days reduced N loss, resulting in higher yields.
At Rossville, corn was N stressed at the time of N application. Although a portion of this stress was overcome by the late-season fertilizer application, yields were still substantially lower than those of adjacent corn that received adequate N earlier in the growing season and did not demonstrate N stress.
At the two farmers' fields, no N stress was observed throughout the season, and no response to late-season N was observed. This demonstrates that considerable N can be supplied by the soil, even on sandy soils with relatively low organic matter.

Introduction
When adequate levels of active, appropriate rhizobia bacteria are present in the soil, soybean plants will nodulate and fix nitrogen and normally not respond to applications of N fertilizer. When soybean is planted into ground that has no history of soybean production or a long interval between soybean crops, natural levels of rhizobia may not be present for successful nodulation and N fixation, and the crop will be N deficient.
Commercial inoculants are usually applied to the seed to supply needed rhizobia and provide adequate nodulation.
In 2009, soybean planted into "virgin" soybean ground or returned conservation reserve program ground in north central Kansas fields was observed to be poorly nodulated and N deficient, even though the seed was properly inoculated with commercial inoculants. A field study was established in one of those fields to determine whether the unnodulated soybean plants would respond to applied N fertilizers and, if so, how much could successfully be used.

Procedures
This study was conducted on a farmer's field near Solomon, KS, that had a noticeably N-deficient soybean crop. Soybean variety NKS 39-A3 was planted no-till into sorghum residue from the previous year on May 20, 2009, at 140,000 seeds/a. A liquid inoculant was sprayed on the soybean seeds as they were loaded into the planter. This field had no history of soybean production. Nitrogen fertilizer was applied on July 20, 2009, to soybean displaying N-deficiency symptoms at the R1 to R2 growth stages. A simple N-rate study with five N rates ranging from 0 to 120 lb/a N was laid out in the field in a randomized complete block design with four replications. The N was applied as urea by surface banding the material between the soybean rows. Rainfall occurred within a few hours of N application.
The two center rows of the four row plots were machine harvested at maturity. Grain moisture was adjusted to 13% moisture content. Data were analyzed statistically with SAS version 9.1 and the PROC GLM procedure with an alpha level of 0.05 for all mean separations.

Results
Results are summarized in Table 1. There was a near-linear significant response to N at this location. The 120 lb/a N rate had a 21 bu/a yield advantage over the unfertilized check. Fertilization was clearly economical in this situation. Additional research will be conducted to further refine appropriate N rates if opportunities develop in the future.

Introduction
This study was conducted in 2009 at the Kansas State University Agronomy North Farm near Manhattan, KS. The objective was to evaluate the response of wheat to N fertilization at Feekes 4, 5, 7, and 9 growth stages at locations where fall N had been applied and where no fall N had been applied. Grain yield and protein levels were used to measure the response to N application timing.

Procedures
Hard red winter wheat variety Santa Fe was no-till planted into soybean stubble at 90 lb/a in late October with a CrustBuster no-till drill. Forty pounds of P 2 O 5 were applied with the drill in furrow at seeding. Nitrogen was applied by treatment. Actual treatments used are listed in Table 1, but these included 0 or 30 lb N in the fall and topdress rates applied in the spring at Feekes 4, 5, 7, or 9. The center 5 ft of each plot was machine harvested after physiological maturity with a plot combine, and grain yield was adjusted to 12.5% moisture.
Data were analyzed using SAS version 9.1 and the PROC GLM procedure with an alpha level of 0.05 for all mean separations.

Results
Grain yield and protein values were increased with N fertilizer (Table 1), but the response was limited. Increasing N rates above 30 lb/a N generally was not productive at this site. However, protein content increased with increasing N rate and with later applications. The highest protein levels were found with 90 lb total N with 60 lb applied at Feekes 7 or Feekes 9.

Summary
Field studies were established in spring 2008 to evaluate the performance of two widely marketed products that claim to enhance availability of soil or fertilizer phosphorus (P): Avail, a P fertilizer enhancer added to commercial fertilizer, and JumpStart, a seed inoculant that infects corn roots and enhances availability of native soil P. This study was continued in 2009 at five locations across north central and northeastern Kansas. All five sites had soil test P levels below the current critical level of 20 ppm and would have been expected to respond to application of P fertilizers.
Excellent corn yields, above 200 bu/a, were obtained at four of the five sites. However, significant responses to applied P were obtained only at Scandia. No significant increase in yield due to the use of Avail or JumpStart was seen at any site where P response was observed.

Introduction
In recent years, the volatile price of P fertilizers has created interest among producers in using products to enhance the efficiency of fertilizers being applied. This project was developed to test two such products widely advertised in Kansas: Avail, a long-chain organic polymer created to reduce fixation of fertilizer P by aluminum and calcium, and JumpStart, a Penicilliam bilaii seed inoculant that increases availability of native soil P to plant roots.

Procedures
This study was established at five locations in northeastern and north central Kansas: Manhattan (Reading silt loam), Scandia (Crete silt loam), Rossville (Eudora sandy loam), Ottawa (Woodson silt loam), and Silver Lake (Rossville silt loam). The Rossville, Scandia, and Silver Lake locations received supplemental irrigation during the growing season. Mehlich-3 P soil tests at each site were: Manhattan, 13 ppm; Scandia, 14 ppm; Rossville, 15 ppm; Ottawa, 11 ppm; and Silver Lake, 13 ppm.
All locations were planted with hybrids adapted to the area at populations appropriate to the respective soils and cropping systems.
Plots were arranged in the field in a randomized complete block design with four replications. There were 14 total treatments consisting of four rates of P fertilizer (0, 10, 20, and 40 lb/a P 2 O 5 broadcast applied as monoammonium polyphosphate; MAP) with and without addition of Avail P enhancer with each of the fertilizer/Avail treatments planted with or without the JumpStart seed treatment. No JumpStart treatments were applied at Silver Lake. Broadcast fertilizer treatments were applied by hand before planting using MAP and MAP commercially impregnated with Avail, obtained locally. All P treatments were balanced for nitrogen with urea, which was broadcast before planting. A total of 160 lb/a N was applied.
Whole plant samples were taken at approximately the V4 growth stage, and ear leaf samples were taken at green silk. Dry matter accumulation and P uptake were calculated at the times of whole plant sampling. Ear leaf samples were analyzed for P concentration only. Results of the plant analyses are not included in this report. At harvest, yield, moisture, and P content of the grain were measured. All yields were corrected to 15.5% grain moisture.
At Ottawa, significant damage to all plots occurred because of greensnap from a severe thunderstorm that occurred at the V16-V18 growth stage. Nearly all plants were lodged, and approximately 30% were broken at the base. The unbroken plants "goosenecked" back up and produced ears.

Results
Individual treatment means for each location and statistical analyses using planned comparisons and contrasts are reported in Table 1. Initial preplant soil tests indicated low available P at all locations. A response to applied P, as indicated by the contrast no P vs. P, was observed only at Scandia. No response to applied P was observed at the other locations, even though the soil tests were below the critical 20 ppm level. One possible explanation for this lack of response to applied P is the good growing conditions and adequate soil moisture throughout the growing season. Phosphorus is known to move to the root for uptake through the soil solution by diffusion. Increasing soil moisture results in a greater portion of soil pores filled with water; this creates continuous water films from soil particle surfaces to the root surface, reducing the distance P ions must diffuse or move and increasing the rate of P supply. Thus, in soils that test lower in P, the rate of P supply will be higher with good soil moisture than under water stress conditions. A recent summary of P soil test correlation and calibration data from Kansas shows that a response to P is expected only about 50% of the time when the soil test is in the range of 13 to 20 ppm, which was the case for most of these sites.
The response to additives was examined using the contrasts no Avail vs. Avail across P rates, no JumpStart vs. JumpStart across rates, no JumpStart vs. JumpStart with no P applied, and no additives vs. both Avail and JumpStart across P rates. Little response to P additives was seen in 2009. At Ottawa, a significant positive response to addition of Avail was observed, using the contrast no Avail vs. Avail across P rates, even though no response to P was seen. No other responses to Avail were seen, even at sites where significant, large responses to P were observed.
No responses to JumpStart alone or JumpStart in combination with P fertilizer were observed. A statistically significant yield reduction due to addition of both Avail and JumpStart in combination across P rates was seen at Scandia.
In summary, response to P fertilizers was limited in 2009, even at sites where soil tests were below the established critical level. No additional response to use of P-enhancing additives was observed, with the exception of a response to addition of Avail at Ottawa.  Introduction Corn growers who have automatic guidance systems technology, such as GPS and auto steer, have the capability to plant corn in precise locations relative to previously established strip-tilled fertilized rows. However, depending on the amount of time that has elapsed between the strip-till fertilizer operations and planting and the rate and forms of fertilizers applied, the best location for planting may not be directly on top of the strip-tilled fertilized rows. For example, strip-tilled fertilized rows could have air pockets under the row, might be dry or cloddy, or could have excessive levels of fertilizer salts or free ammonia. On the other hand, planting too far away from the strip-tilled fertilized rows might reduce benefits from residue management including warmer loosened soil and rapid root-to-fertilizer contact. The objective of this study was to determine the effects of planting corn at various distances from the center of previously established strip-tilled fertilized rows on fine-textured soils in eastern Kansas.

Procedures
Field experiments were conducted on an Osage silty clay loam soil at a field site near Lane, KS, in 2006 and 2008 and on a Woodson silt loam soil at the East Central Kansas Experiment Field at Ottawa, KS, in 2009. The planting distances evaluated were directly on top of strip-tilled fertilized rows and 3.75, 7.5, and 15 in. off the center of the rows. The experiment was designed as a randomized complete block with three to four replications. Plot size ranged from 0.14 to 0.55 acres depending on the site year. The strip-till fertilization application was performed 1 day before planting in 2006, 2 weeks before planting in 2008, and 2.5 months before planting in 2009. Fertilizer was applied at a standard rate (120-30-10 lb/a). The fertilizer source was a mixture of dry urea, diammonium phosphate, and muriate of potash. Depth of the strip-till fertilizer application was 5 to 6 in. below the row. The planting treatments were evaluated for effects on plant population, early season corn growth, nutrient uptake, and grain yield.

Results
In 2006 and 2008, plant populations were higher for corn planted 3.75 in. off the center of the strip-tilled fertilized rows than for corn planted directly on top of the rows (Figure 1). This was expected in 2006 because the strip-till fertilization operation was performed only 1 day before planting and the soil was loose and had air pockets under the row. In 2008, when there were 2 weeks between the strip-till operation and planting, plant population was still increased by planting just slightly off the strip-tilled fertilized rows. No differences in plant populations occurred in 2009, when the strip-till operation was performed 2.5 months before planting.
Early season corn growth at the 2-to 3-and 6-to 7-leaf growth stages tended to be better for corn planted directly on top of the strip-tilled fertilized rows or just slightly off (3.75 in. off) than for corn planted 7.5 and 15 in. off the center of the rows (Figures  2A and 2B). Planting corn 7.5 in. from the center of the strip-tilled fertilized rows reduced early season corn growth 12% on average, and planting 15 in. away reduced early season growth 38%. Uptake of plant nutrients (i.e., nitrogen, phosphorus, and potassium) followed a pattern similar to that for plant growth (data not shown).
In 2006, yield of corn planted directly on top of the strip-tilled fertilized rows was 8% less that that of corn planted 3.75 in. off the center of the rows (Figure 3). This was a result of the reduced plant population. In 2008, corn planted 3.75 in. off the center of the strip-tilled fertilized rows had the highest plant population and the highest numerical grain yield. In 2009, when the strip-till operation was performed 2.5 months before planting and there was plenty of time for the strip-tilled seedbed to settle and become firm, there were no differences in plant population and no differences in yield between planting directly on the strip-tilled rows and planting 3.75 in. off the rows.
These results indicate that the best location for planting will vary depending on the condition of the strip-tilled fertilized seedbed and the amount of time between planting and when the strip-till fertilizer operation was performed. Corn should be planted in a moist, firm seedbed to obtain good stands and within 3.75 in. of strip-tilled fertilized rows to ensure quick contact between corn roots and fertilizer.
Additional years testing are needed to determine if these guidelines might also apply to strip-tilled fertilized corn planted on course-textured soils and when higher rates of fertilizer and other sources of nitrogen are applied.

Introduction
This study was funded by a grant provided by Tessenderlo Kerley, Inc., a producer of specialty products used in the agriculture, mining, and process chemical industries. The Tessenderlo Kerley products tested were CaTs (0-0-0-10S-6Ca), Trisert NB (26-0-0 with 33% slow-release N), and MagThio (0-0-0-10S-4Mg). A lower-than-optimal N rate (60 lb/a) was used to evaluate the effectiveness of Trisert NB at supplying foliar N to sorghum plants to increase grain yield. Applications of CaTs and MagThio with urea-ammonium nitrate (UAN) solution were also evaluated for their effect on grain yield at the lower N rate.

Procedures
This study was conducted in 2009 on no-till dryland grain sorghum following soybean on a Woodson silt loam soil at the East Central Kansas Experiment Field near Ottawa, KS. Treatments were: a no-N check; 90 and 60 lb/a N; 60 lb/a N + 5 or 10 gal/a CaTs; 60 lb/a N + 5 gal/a CaTs + 4 gal/a foliar N; 60 lb/a N + 4 gal/a foliar N; and 60 lb/a N + 1.0, 1.5, or 2.0 gal/a MagThio. Urea-ammonium nitrate solution was used as the N source and knifed 6 to 8 in. deep on 30-in. centers. Grain sorghum hybrid Pioneer 84G62 was planted no-till into soybean stubble at 65,000 seeds/a on May 18. The UAN, CaTs, and MagThio treatments were applied on 30-in. centers between the planted rows on May 19. The Trisert NB treatments were applied in 20 gal/a solution to 10-leaf sorghum on July 13. Herbicides were applied as needed for weed control. Flag leaf samples were taken at boot stage of growth for N and P analyses. Plots were harvested with a John Deere 3300 plot combine, and grain samples were saved for N and P analyses.

Results
Nitrogen content of sorghum leaf tissue at boot stage responded to N rate ( Table 1). The check plot had the lowest N content, the 90 lb/a N rate had the highest, and the treatments with the 60 lb/a N rate were intermediate. Phosphorus content of the grain was the reverse of the leaf N content; the check plot had the highest P content, the 90 lb/a N rate had the lowest, and the treatments with the 60 lb/a N rate were again intermediate. However, there were no significant differences in leaf tissue P content or grain N content. All treatments increased yield of dryland sorghum over that of the no-N check. The 90 lb/a N rate yielded 20 bu/a more than most of the other 60 lb/a N treatments, but there were no significant differences among the treatments receiving 60 lb/a N as UAN.

Introduction
This study was initiated in 1972 at the Paramore Unit of the Kansas River Valley Experiment Field to evaluate effects of N, P, and K on furrow-irrigated soybean. In 1983, the study was changed to a corn/soybean rotation with corn planted and fertilizer treatments applied in odd years. In 2002, sprinkler irrigation with a linear move irrigation system replaced the furrow irrigation. Study objectives are to evaluate effects of N, P, and K applications to a corn crop on grain yields of corn and the following soybean crop and on soil test values.

Results
Average corn yields for the 7-year period from 1983 to 1995 and yields for 1997 to 2009 are shown in Table 1. Yields were maximized with 160 lb/a N in most years. Fertilization at 240 lb/a N did not significantly increase corn yield. From 1997 to 2009, corn yield with 120 lb/a N was not significantly different from that with 160 lb/a N and ranged from 0 to 8 bu/a less (LSD 0.05 was 11 to 19 bu/a). A yield response to P fertilization was obtained in 1985 and 1993 (yearly data not shown), but the 7-year average showed no significant difference in yield. No P response was observed in 1997, when starter fertilizer was applied to all plots. A significant yield response to P was obtained in 2003. The 7-year average from 1997 to 2009 showed a nonsignificant 7 bu/a yield increase for the 60 lb/a P 2 O 5 treatment over that when no P was applied. Fertilization with K resulted in a significant yield increase in 1985, 1989, and 1993 (yearly data not shown), and the 7-year average showed a 6 bu/a yield increase. No significant corn yield response to K fertilization was observed from 1997 to 2009. No significant interactions between N, P, and/or K were observed. However, in 2005 and 2009, the years with the highest corn yields, the 160-60-150 treatment had the highest grain yield. This suggests a balanced fertility program is necessary for best yields in good production years.  1983-1995 1997 1999 1 Fertilizer applied to corn in odd years from 1983 to 2009 and to soybean for 11 years prior to 1983 (the first number of two is the rate applied to corn from 1983 to 1995). 2 Potassium treatments were not applied in 1997. Starter fertilizer of 10 gal/a of 10-34-0 was applied to all treatments in 1997 and 1998 (corn and soybean). Nitrogen and potassium treatments were applied to corn in 1997.

Introduction
This study was conducted with a grant provided by Tessenderlo Kerley, Inc., a producer of specialty products used in the agriculture, mining, and process chemical industries.

Results
Soybean yields are shown in Table 1. Yields for the untreated check were 59.9 and 69.6 bu/a in 2008 and 2009, respectively. Although yield increases of up to 4.0 bu/a in 2008 and 6.0 bu/a in 2009 were observed with some treatments, these yield increases were not statistically significant.

Summary
Predominant cropping systems in south central Kansas have been continuous wheat and wheat/grain sorghum/fallow. With continuous wheat, tillage is preformed to control diseases and weeds. In the wheat/sorghum/fallow system, only two crops are produced every 3 years. Other crops (corn, soybean, sunflower, winter cover crops, and canola) can be placed in these cropping systems. To determine how yields of winter wheat and alternative crops are affected by alternative cropping systems, winter wheat was planted in rotations following the alternative crops. Yields were compared with yield of continuous winter wheat under conventional tillage (CT) and no-till (NT) practices. Initially, CT continuous wheat yields were greater than those from the other systems. However, over time, wheat yields following soybean have increased, reflecting the effects of reduced weed and disease pressure and increased soil nitrogen (N). However, CT continuous winter wheat seems to out yield NT winter wheat regardless of the previous crop.

Introduction
In south central Kansas, continuous hard red winter wheat and winter wheat/grain sorghum/fallow are the predominant dryland cropping systems. A summer fallow period following sorghum is required because the sorghum crop is harvested in late fall, after the optimum planting date for wheat in this region. Average annual rainfall is only 30 in./year, with 60% to 70% occurring between March and July. Therefore, soil moisture is often not sufficient for optimum wheat growth in the fall. No-till systems often increase soil moisture by increasing infiltration and decreasing evaporation. However, higher grain yields associated with increased soil water in NT have not always been observed. Cropping systems with winter wheat following several alternative crops would provide improved weed control through additional herbicide options, reduce disease incidence by interrupting disease cycles, and allow producers several options under the 1995 Farm Bill. However, the fertilizer N requirement for many crops is often greater under NT than CT. Increased immobilization and denitrification of inorganic soil N and decreased mineralization of organic soil N have been related to the increased N requirements under NT. Therefore, effect of N rates on hard red winter wheat in continuous wheat and in cropping systems involving alternative crops for the area have been evaluated at the South Central Kansas Experiment Field. The continuous winter wheat study was established in 1979 and restructured to include a tillage factor in 1987. The first of the alternative cropping systems in which wheat follows short-season corn was established in 1986 and modified in 1996 to a wheat/cover crop/ grain sorghum rotation and in 2007 to a wheat/grain sorghum/canola cropping system. The second alternative cropping system, established in 1990, has winter wheat follow-ing soybean. Both cropping systems are seeded NT into the previous crop's residue. All three systems have the same N rate treatments.

Procedures
The research is conducted at the South Central Kansas Experiment Field-Hutchinson. Soil is an Ost loam. The sites were in wheat prior to the start of the cropping systems. The research is replicated four or five times in a randomized block design with a splitplot arrangement. The main plot is crop, and the subplot is six N levels (0, 25, 50, 75, 100, and 125 lb/a). Nitrogen treatments were broadcast applied prior to planting as NH 4 NO 3 and as urea after ammonium nitrate became unavailable. Phosphate is applied in the row at planting. All crops were produced each year of the study and planted at the normal time for the area. Plots are harvested at maturity to determine grain yield, moisture, and test weight.

Continuous Wheat
These plots were established in 1979 and modified (split into subplots) in 1987 to include both CT and NT. The CT treatments are plowed immediately after harvest and then worked with a disk as necessary to control weed growth. Fertilizer rates are applied with a Barber metered screw spreader prior to the last tillage (field cultivation) on the CT plots and seeding of the NT plots. Plots are cross seeded in mid-October to winter wheat. Because of a cheat infestation in the 1993 crop, plots were planted to oat in spring 1994. Fertility rates were maintained, and the oat crop was harvested in July. Winter wheat has been planted in mid-October each year in the plots since fall 1994. New herbicides have helped control cheat in the NT treatments. These plots were seeded to canola in fall 2005 and then back to wheat in October 2006. We hoped this would provide field data on the effects of canola on wheat yields in a continuous wheat cropping system. However, an extended freeze the first week of April had a major effect on wheat yields as discussed in the results section. Hail adversely affected wheat yields in 2008, but wheat yields were average in 2009.

Wheat After Corn/Grain Sorghum/Fallow
Winter wheat is planted after short-season corn is harvested in late August to early September. This early harvest of short-season corn allows the soil profile water to be recharged (by normal late summer and early fall rains) before winter wheat is planted in mid-October. Fertilizer rates are applied with the Barber metered screw spreader in the same manner as for continuous wheat. In 1996, the corn crop in this rotation was dropped and three legumes (winter pea, hairy vetch, and yellow sweet clover) were added as winter cover crops. Thus, the rotation became a wheat/cover crop/grain sorghum/fallow rotation. The cover crops replaced the 25, 75, and 125 lb/a N treatments in the grain sorghum portion of the rotation. Yield data can be found in Field Research 2000, Kansas Agricultural Experiment Station Report of Progress 854.

Wheat After Soybean
Winter wheat is planted after soybean is harvested in early to mid-September. As with the continuous wheat plots, these plots are planted to winter wheat in mid-October. Fertilizer rates are applied with the Barber metered screw spreader in the same manner as for continuous wheat. Since 1999, a group III soybean has been used. This delayed harvest from late August to early October. In some years, this effectively eliminates the soil profile water recharge time prior to wheat planting.

Wheat After Grain Sorghum in a Cover Crop/Fallow/Grain Sorghum/Wheat Rotation
Winter wheat is planted into stubble from grain sorghum harvested the previous fall. Thus, soil profile water has had 11 months to recharge before winter wheat is planted in mid-October. Nitrogen fertilizer is applied at a uniform rate of 75 lb/a with the Barber metered screw spreader in the same manner as for the continuous wheat. This rotation was terminated after the harvest of each crop in 2006. In fall 2006, canola was introduced into this rotation in place of the cover crops. The winter canola did not establish uniformly, so spring canola was seeded into these plots to establish canola stubble for the succeeding crop.
Winter wheat is also planted after canola and sunflower to evaluate the effects of these two crops on winter wheat yield. Uniform N fertility is used; therefore, this data is not presented. Yield of wheat after these two crops is similar to yield of wheat after soybean.

Results
Unlike 2008 wheat yields, which were affected by hail, 2009 wheat yields reflected the favorable moisture conditions in the spring. Wheat yields in 2009 were closer to average yields for the time period of these studies.

Continuous Wheat-Canola 2006
Continuous winter wheat grain yield data from the plots are summarized by tillage and N rate in Table 1. Data for years prior to 1996 can be found in Field Research 2000, Kansas Agricultural Experiment Station Report of Progress 854. Conditions in 1996 and 1997 were excellent for winter wheat production in spite of the dry fall of 1995 and the late spring freezes in both years. Excellent moisture and temperatures during the grain filling period resulted in decreased grain yield differences between the CT and NT treatments within N rates. Conditions in the springs of 1998 and 1999 were excellent for grain filling in wheat. However, differences in yield between CT and NT wheat were still expressed. In 2000, differences were wider up to the 100 lb/a N rate. At that point, differences were similar to those of previous years (data for the years 1996 through 2000 can be found in Agronomy Field Research 2006, Kansas Agricultural Experiment Station Report of Progress 975). The wet winter and late spring of the 2003-2004 harvest year allowed for excellent tillering, grain fill, and yields (Table 1). In 2005, the dry period in April and May seemed to affect yields in the 0 and 25 lb/a N rate plots. These plots were seeded to canola in fall 2005. Canola in the NT plots did not survive. Yield data for the CT plots is presented in Table 1. There was a yield increase for each increase in N rate. However, the increase was not significant above the 50 lb/a rate. All N fertilizer was applied in the fall, and effects of the winterkill were more noticeable at the lower N rates. An N-rate study with canola was established at the Redd Foundation land to more fully evaluate effects of fertility on canola. Wheat planted after canola (2007 harvest) looked promising until the April freeze. Because of the growth stage at the time of the freeze, the lower N rate and NT treatment had higher yields than the CT and higher N rate treatments ( Table 1). The higher yielding treatments were slightly behind the other plots when the freeze hit; thus, they were not affected as severely by the freeze. The continuous wheat plots were not harvested for yield data in 2008 because of the severe hail damage from the May 5 storm. Yields in 2009 were excellent because moisture and temperatures during grain filling were ideal for winter wheat.

Wheat After Soybean
Wheat yields after soybean also reflect differences in N rate. However, wheat yields from this cropping system are compared with yields from systems in which wheat followed corn, effects of residual N from soybean production in the previous year are evident, particularly for the 0 to 75 lb/a N rates in 1993 and the 0 to 125 lb/a rates in 1994. Yields for 1995 reflect the added N from the previous soybean crop with yield by N rate increases similar to those of 1994. The 1996 yields with spring wheat reflect the lack of response to N fertilizer in spring wheat. Yields for 1997 and 1998 leveled off after the first four increments of N. As with wheat in the other rotations in 1999, ideal moisture and temperature conditions allowed wheat yields after soybean to express differences in N rate up to the 100 lb/a N rate. In the past, those differences stopped at the 75 lb/a N rate. Compared with continuous wheat yields, rotational wheat is starting to reflect the presence of the third crop (grain sorghum) in the rotation. Wheat yields were lower in 2000 than in 1999. This is due to the lack of timely moisture in April and May and the hot days at the end of May.  (Table 2). However, the trend for N credits to soybean seems to have continued. As with the continuous wheat cropping system, yields for the 0 and 25 lb/a N rates were less than those for the 50 to 125 lb/a rates, but the differences are not significant. Wheat yields for 2009 continued to reflect the N added by the soybean crop in the cropping sequence. As the rotation continues to cycle, differences at each N rate will probably stabilize after four to five cycles, potentially reducing fertilizer N applications by 25 to 50 lb/a in treatments in which wheat follows soybean.

Wheat After Grain Sorghum/Cover Crop
These plots were severely damaged by hail on May 5, 2008, and, therefore, were not harvested for yield data in 2008. This is only the second time that the wheat plots were not harvested since the rotations were started in this location in 1986. The first year that wheat was harvested after a cover crop/grain sorghum planting was 1997. Data for the years 1997 through 2000 can be found in Agronomy Field Research 2006, Kansas Agricultural Experiment Station Report of Progress 975. From 1997 to 2000, there did not appear to be a definite effect of the cover crop on yield. This is most likely due to the variance in cover crop growth within a given year. In years such as 1998 and 1999 when sufficient moisture and warm winter temperatures produced good cover crop growth, additional N from the cover crop appears to carry through to wheat yields. Because of the fallow period after sorghum in this rotation, the wheat crop has a moisture advantage over wheat after soybean. Cheat was the limiting factor in this rotation in 2003. More aggressive herbicide control of cheat in the cover crops was started, and 2004 yields reflect the control of cheat. Management of grasses in the cover crop portion of this rotation seems to be the key factor in controlling cheat and increasing yields. This is evident when yields for 2005 and 2006 (Table 3) are compared with continuous wheat yields or yields from wheat in rotation with soybean. Because of the stage of development at the time of the April freeze, wheat yields in these plots were more adversely affected than yields of plants in other rotations. We think that lack of a third crop taken to maturity has positively influenced yields. The canola did not survive the winter; thus, wheat yields in 2009 do not reflect the presence of a canola crop in the cropping sequence.

Other Observations
Nitrogen application significantly increased grain N content in all crops. Grain phosphate levels did not seem to be affected by increased N rate.
Loss of the wheat crop after corn can occur in years when fall and winter moisture are limited. This loss has not occurred in continuous winter wheat regardless of tillage or in wheat after soybean. Corn has potential to produce grain in favorable (cool and moist) years and silage in non-favorable (hot and dry) years. In extremely dry summers, extremely low grain sorghum and soybean yields can occur. The major weed control problem in the wheat-after-corn system is grasses. This was expected, and work is being done to determine the best herbicides and time of application to control grasses.

Soybean and Grain Sorghum in the Rotations
Soybean was added to intensify the cropping system in south central Kansas. Soybean, a legume, can add N to the soil system. Thus, N rates are not applied when soybean is planted in the plots for the rotation. This provides opportunities for following crops to use the added N and to check yields against yields for the crop in other production systems. Yield data for soybean following grain sorghum in the rotation are given in Table 4. Soybean yields are affected more by the weather for the given year than by the previous crop. This is seen in yields for 2001, 2003, 2005, 2006, 2007, and 2008, when summer growing season moisture was limiting. As in 2007, a combination of a wet spring that delayed planting and a hot, dry period from July through early September 2008 affected yields. Planting was again delayed because of above-average rains in April. There has been a significant effect of N on soybean yield in only 3 out of the 13 years that the research has been conducted. In the 2 of the 3 years that N application rate affected yield, it did so only at the lower N rates.
Yield data for grain sorghum after wheat in the soybean/wheat/grain sorghum rotation are shown in Table 5. As with soybean, weather is the main factor affecting yield. Addition of a third cash crop (soybean), which intensifies the rotation (cropping system), will reduce the yield of grain sorghum in the soybean/wheat/grain sorghum vs. the wheat/cover crop/grain sorghum rotation (Tables 5 and 6). More uniform yields were obtained in the soybean/wheat/grain sorghum rotation (Table 5) than in the wheat/ cover crop/grain sorghum rotation ( Table 6). The lack of precipitation in 2005 and 2006 can be seen in grain sorghum yields for 2006. As with soybean, the combination of a wet spring that delayed planting and the hot, dry period from July through early September affected yields. The cool, wet weather in September and October 2008 delayed maturation, and the grain did not dry down until after the first killing frost.
Grain sorghum yields were reduced in the intensified cropping system (soybean, wheat, and grain sorghum) compared with the less intense rotation (wheat, winter cover crop, grain sorghum).

Introduction
Many crop rotation systems are used in southeastern Kansas. This experiment is designed to determine the long-term effect of selected tillage and N fertilizer placement options on yields of short-season corn, wheat, and double-crop soybean in rotation.

Procedures
A split-plot design with four replications was initiated in 1983 with tillage system as the whole plot and N treatment as the subplot. In 2005, the rotation was changed to begin a short-season corn/wheat/double-crop soybean sequence. Use of three tillage systems (conventional, reduced, and no-till) continues in the same areas used during the previous 22 years. The conven tional system consists of chiseling, disking, and field cultivation. Chiseling occurs in the fall preceding corn or wheat crops. The reducedtillage system consists of disking and field cultivation prior to planting. Glypho sate (Roundup) is applied to the no-till areas. The four N treatments for the crop are: no N (control), broadcast urea-ammonium nitrate (UAN; 28% N) solution, dribble UAN solution, and knife UAN solution at 4 in. deep. The N rate for the corn crop grown in odd-numbered years is 125 lb/a. The N rate of 120 lb/a for wheat is split as 60 lb/a applied preplant as broadcast, dribble, or knifed UAN. All plots except the controls are top-dressed in the spring with broadcast UAN at 60 lb/a N.

Results
In 2008, adding fertilizer N, in general, doubled wheat yields compared with the no-N controls ( Figure 1). Wheat yield was affected by an interaction between tillage and N placement. With conventional and reduced tillage, there were no differences in yield due to placement method. In no-till, knife application of fertilizer N resulted in nearly 50% greater yield than broadcast or dribble applications but did not fully compensate for yield reduction with no-till. Although double-crop soybean yields were not affected by the residual effect of N placement or an interaction of N placement with tillage (data not shown), no-till soybean yield was 3 to 4 bu/a less than yields with conventional or reduced tillage (Figure 2).

Introduction
Corn acreage has increased in southeastern Kansas in recent years because of the introduction of short-season cultivars that enable producers to plant in the upland, claypan soils typical of the area. Short-season hybrids reach reproductive stages earlier than full-season hybrids and thus may partially avoid midsummer droughts, which are often severe on these claypan soils that have limited plant-available moisture storage.
Optimum corn production results from proper management of soil fertility, tillage, and other practices. However, ideal soil fertility and other management options have not been well defined for short-season corn production in southeastern Kansas. Reducing tillage has the potential to reduce soil and nutrient losses to the environment, and maintaining proper plant nutrition is critical for crop production. Starter fertilizers have been used to improve early plant growth in no-till or reduced-tillage systems, and this often translates to additional yield. However, data are limited regarding the effect of starter fertilization on yield of short-season corn grown on the claypan soils found in areas of the eastern Great Plains. The objective of this study was to determine the effect of nitrogen (N) and P rates in starter fertilizers on short-season corn planted with reduced tillage or no-till.

Procedures
The experiment was conducted in 2008 at the Kansas State University Southeast Agricultural Research Center at Parsons, KS. The soil was a Parsons silt loam with a claypan subsoil. Selected background soil chemical analyses in the 0-to 6-in. depth were pH 6.5 (1:1 soil:water), 5 ppm P (Bray-1), 65 ppm K (1 M NH 4 C 2 H 3 O 2 extract), 5.3 ppm NH 4 -N, 6.4 ppm NO 3 -N, and 2.8% organic matter. The experimental design was a split-plot arrangement of a randomized complete block with three replications. The whole plots were tillage system (reduced tillage and no-till), and subplots were starter N-P combinations. Nine of the subplots were starter fertilizer combinations in which N rates were 20, 40, and 60 lb/a and P rates were 0, 25, and 50 lb/a P 2 O 5 . In addition, there were two reference subplot treatments: a no-starter treatment (all N and P applied preplant) and a control with no N or P. All plots except the no N-P control were balanced to receive a total of 120 lb/a N and 50 lb/a P 2 O 5 . The N and P fertilizer sources were 28-0-0 and 10-34-0 fluids. All plots received 60 lb/a K 2 O as solid KCl broadcast preplant. Pioneer 35F37 Roundup Ready corn was planted at 25,000 seeds/a on Apr. 16, 2008. Starter solutions were applied 2 × 2 with the planter. Grain was harvested for yield on Sept. 19, 2008, with a small-plot combine equipped with a corn head.

Results
Although rainfall was variable, environmental conditions were more favorable than in the past 2 years, resulting in overall corn yields in 2008 near 150 bu/a. However, corn yields were not improved by use of starters in 2008. Average corn yield with starters was 8 bu/a less than with all N and P fertilizer applied broadcast prior to planting (Table 1). This yield difference appeared to be due to a greater number of kernels per ear in the treatment with all N and P broadcast prior to planting. Even though early growth appeared to be improved with the highest P rate in the starter, this effect did not persist by the reproductive stages of growth (Table 2). A rate of 40 lb/a N in the starter resulted in greater dry matter production at R1 compared with 20 lb/a N, but this effect was not apparent at any other growth stage. At the R4 (dough) growth stage, dry matter production was not significantly affected by any treatment including the control.

Summary
In 2008, irrigation applied at both the VT and R2 growth stages increased total fresh weight but not number of ears or individual ear weight. Earlier planting increased total ears, total fresh weight, and individual ear weight. Knife application increased total sweet corn fresh weight, but nitrogen (N) placement had no effect on number of ears or individual ear weight.

Introduction
Sweet corn is a possible value-added, alternative crop for producers in southeastern Kansas. Corn responds to irrigation, and timing of water deficits can affect yield components. Even though large irrigation sources, such as aquifers, are lacking in southeastern Kansas, supplemental irrigation could be supplied from the substantial number of small lakes and ponds in the area. However, there is a lack of information on effects of irrigation management, N placement, and planting date on performance of sweet corn, which may hinder producers' adoption of this crop.

Procedures
The experiment was established on a Parsons silt loam in spring 2008 as a split-plot arrangement of a randomized complete block with three replications. The whole plots included two planting dates (targets of late April and mid-May) and four irrigation schemes: (1) no irrigation, (2) 1.5 in. at VT (tassel), (3) 1.5 in. at R2 (blister), and (4) 1.5 in. at both VT and R2. Subplots were three N treatments consisting of no N and 100 lb/a N applied broadcast or as a subsurface band (knife) at 4 in. Sweet corn was planted on Apr. 22 and May 19, 2008. Sweet corn from the first planting date was picked on July 14 and 18, and corn from the second planting date was picked on Aug. 1 and 6, 2008.

Results
The total number of ears was 15% greater from sweet corn planted in April than sweet corn planted in May (Table 1), and there was a similar difference in individual ear weight. As a result, total fresh weight was more than 30% greater for sweet corn planted in April than in May. Limited irrigation applied at both the VT and R2 growth stages resulted in more than 10% greater total fresh weight than no irrigation or irrigation at only one growth stage. Irrigation did not increase number of ears per acre or individual ear weight. Nitrogen placement did not affect number of ears or individual ear weight, but knifing increased total fresh weight by about 10% above broadcast N or no N fertilizer. The minimal response to fertilizer N may be a result of the plot area being fallowed the previous year.

Introduction
In southeastern Kansas, producers typically double-crop soybean after wheat, but other double-crop options are suitable for the growing conditions of this region. Grain sorghum can be grown successfully as a double-crop option if planted by early July. If wet conditions follow wheat harvest, double-crop sunflower can be planted as late as mid-to late July. Small-seeded legumes, such as lespedeza or sweet clover, typically are seeded into wheat in late winter. Lespedeza commonly is grown for seed or cut for hay, and sweet clover is planted primarily for soil amendment purposes. Fewer producers summer fallow land after wheat harvest. Previous wheat and double-crop systems likely affect growth of subsequent crops, such as corn. In addition, N fertilizer requirements for corn might need to be adjusted depending on the previous wheat and double-crop system used.

Procedures
The study was conducted at the Parsons Unit of the Southeast Agricultural Research Center. The experimental design was a split-plot arrangement with three replications. Main plots consisted of six different systems: (1)

Introduction
Because of recent increases in fertilizer N prices, producers are looking for ways to reduce production costs for feed-grain crops, such as corn and grain sorghum. One method that has gained renewed interest is applying some of the fertilizer N requirement after the crop has emerged, referred to as side-dressing. Some research has shown that a subsurface application of banded N after the crop has emerged results in more efficient N use and often increases net return. In southeastern Kansas, excessive spring rainfall also increases the potential for greater N loss where fertilizer N is applied preplant.

Procedures
Studies were conducted at the Columbus Unit of the Southeast Agricultural Research Center from 2005 through 2009 to evaluate the effects of time and rate of fertilizer N application for both corn and grain sorghum. Fertilizer N (28% liquid N) treatments consisted of different N rates applied preplant or side-dressed. Preplant fertilizer N was subsurface applied in mid-March on 15-in. centers at a depth of 4 to 6 in. Sidedress N also was subsurface applied between 30-in. rows during the early growing season. All plots received 30 lb/a N preplant as 18-46-0. The previous crop was double-crop soybean.

Results
Wet soil conditions in early spring prevented corn from being planted in 2009. Corn yields for 2008 and 3-year averages are shown in Table 1. Grain sorghum yield results for 2009 and 4-year averages also are included in Table 1. In this study, both corn and grain sorghum yields responded more to rate than time of fertilizer N application. Even though soil moisture was excessive during early spring in several years, denitrification loses evidently were small at this silt loam site, where water did not pond on the soil surface.

Introduction
In southeastern Kansas, wheat is commonly planted after a summer crop, such as corn, grain sorghum, or soybean, to diversify crop rotation. Improved equipment technology has made no-till planting of wheat more feasible in high-residue conditions. The benefits of planting wheat no-till are reduced labor and tillage costs and less soil erosion. Leaving crop residues near the soil surface, however, affects fertilizer N management for no-till wheat.

Procedures
The experiment was a split-plot design, in which main plots were previous crops (corn, grain sorghum, and soybean) and subplots were three fertilizer N methods and three N application times. Application methods were: (1) subsurface knife of 28% N (coulter-knife on 15-in. spacing at a depth of nearly 4 in.), (2) surface strip-band of 28% N (15-in. strip bands on soil surface), (3) surface broadcast of 28% N using TeeJet streamer nozzles, and (4) surface broadcast of urea (46% N). The N application times were: (1) 1/3 of the N in fall followed by 2/3 in late winter, (2) 2/3 of the N in fall followed by 1/3 in late winter, and (3) all N applied in fall. All plots also received 100 lb/a of 18-46-0 and 100 lb/a of 0-0-60. Wheat was planted on October 21 with a no-till drill in 7.5-in. spacing at a seeding rate of 100 lb/a.

Results
In 2009, wheat yields were reduced because of excessive rainfall in April and May, which resulted in a severe scab disease infection after wheat heading. Wheat yields were highest following soybean, and yields generally were similar following either corn or grain sorghum (Table 1). However, fertilizer N responses varied with previous crop. When wheat followed grain sorghum, N application method and time of N application resulted in more significant yield responses compared with wheat following soybean or corn.

Introduction
More producers are planting winter wheat no-till into previous crop residues as a means of reducing labor and tillage costs. However, the large amount of crop residue left on the soil surface in no-till systems can make N management difficult. Loss of N as ammonia (NH 3 ) is a concern in no-till crop production when urea-containing fertilizers are applied to the soil surface. The use of urease inhibitors, such as Agrotain and Nutrisphere, applied with urea-containing fertilizers has been shown to reduce ammonia volatilization losses. In addition, a slow-release polymer-coated urea (ESN) has become available as an N management product. Ammonium thiosulfate (ATS) also has the ability to slow soil urease activity and delay urea hydrolysis. This study compared the effects of various fertilizer N sources and urease inhibitors applied in late winter to no-till wheat following corn.

Procedures
Winter wheat was planted in mid-October 2008 following corn harvest at the Parsons Unit of the Southeast Agricultural Research Center. Wheat was planted no-till in 7.5-in. spacing at a seeding rate of 100 lb/a. All plots received a preplant broadcast application of 100 lb/a of 18-46-0. Various fertilizer N sources were applied in late February at a rate of 75 lb/a N. Fertilizer N treatments were ESN, Nutrisphere-N + urea-ammonium nitrate solution (UAN; 28%N), Agrotain + UAN, UAN + ATS, UAN alone, urea, and ammonium nitrate. Liquid UAN treated with urease inhibitors was broadcast on the soil surface using TeeJet nozzle streamers. In addition, effects of UAN as a broadcast application on the soil surface and as a subsurface treatment applied on 15-in. centers with a coulter-shank applicator were compared.

Results
Grain yields were reduced because of excessive rainfall in April and May, which resulted in moderate scab disease infection after wheat headed. However, wheat yields were significantly affected by fertilizer N source. Applying a urease inhibitor with UAN generally increased wheat yield compared with UAN alone and surface-applied urea. Additional research conducted under various environmental conditions is needed to evaluate the effectiveness of urease inhibitors with urea-containing N fertilizer sources.

Introduction
Timing and rate of fertilizer P and K application are important crop production management decisions. In southeastern Kansas, producers often plant wheat following harvest of a feed-grain crop, such as grain sorghum or corn, and then plant doublecrop soybean after wheat, giving three crops in 2 years. In these multiple-crop systems, producers typically apply fertilizer P and K only to the feed-grain and wheat crops. Because fertilizer costs are increasing, this research seeks to determine direct and residual effects of P and K fertilizer rate and time of application on grain yields in a double-cropping system.

Procedures
This study was established in 2004 at the Columbus Unit of the Southeast Agricultural Research Center. The crop rotation consists of grain sorghum/(wheat/double-crop soybean), giving three crops in a 2-year period. Grain sorghum is planted with conventional tillage, and wheat and double-crop soybean are planted no-till. Different fertilizer P and K rates are applied preplant to the grain sorghum crop only or to both the grain sorghum and wheat crops. Initial soil test values before study establishment were 23 ppm Bray-1 P and 160 ppm exchangeable K for the 0-to 6-in. soil depth.

Results
Effects of various fertilizer P and K treatments on grain sorghum, wheat, and doublecrop soybean yields are shown in Table 1. Fertilizer treatment has affected grain yields very little during first two cropping cycles. The nonsignificant yield response to fertilizer P and K was not unexpected because initial soil test values indicated that soil values of P and K were sufficient for the expected yield goals. Results of soil analyses after two complete cropping cycles are shown in Table 2. Soil P and K levels are beginning to change from initial values. Soil sampling will continue over time to monitor changes in soil nutrient levels.
Soil test values after two complete cropping cycles.

Introduction
Warm-season grass is needed to fill a production void left in forage systems by cool-season grasses. Crabgrass could fill this niche by providing high-quality forage in summer. Although crabgrass is an annual species, it is a warm-season grass that has the capacity to reseed itself. Crabgrass requires N for optimum production, but little is known about its needs or responses to different nitrogen management alternatives.

Procedures
The plot area at the Mound Valley Unit of the Southeast Agricultural Research Center was fertilized with 0-60-60 lb/a N-P 2 O 5 -K 2 O beginning in May 2005. Shortly thereafter, the plot was seeded with 5 lb/a pure live seed of 'Red River' crabgrass [Digitaria ciliaris (Retz.) Koel.] with a Brillion seeder. In addition to natural reseeding, another 3 lb/a pure live seed was broadcast each spring thereafter, another 0-60-60 lb/a N-P 2 O 5 -K 2 O was applied, and the plot area was rotary hoed.
The three N treatments (rates, sources, and timing) and a check were arranged in a

Results
Forage yields responded to N fertilizer treatments somewhat differently in the 3 years, so these results are shown by year (Table 1). Nitrogen rate significantly (P<0.05) affected first-cut and total yield in 2006 and all yields in 2007; the 50-lb rate yielded less than the higher rates (factorial means not shown). The split N application produced less forage in cut 1 of 2006 and 2008 but more in cut 2 of 2007and 2008 compared with a single application. The only effect of source in the first 2 years was in cut 2 of 2007, when urea resulted in more forage than ammonium nitrate.
In 2008, a significant N rate by N source interaction for first-cut and total yield resulted from the sources having similar yields for all except the 200 lb/a rate, for which urea produced more than ammonium nitrate (factorial means not shown). Further, yield with ammonium nitrate seemed to peak at the 150 lb/a rate because that treatment yielded as much as the 200 lb/a rate of urea. Otherwise, treatment with 50 lb/a N yielded significantly less first-cut and total forage than th e 100 and 150 lb/a N rates regardless of source. In the second cutting, yield from ammonium nitrate application increased between 50 and 100 lb/a N but declined at the 200 lb/a N rate, whereas urea application rates from 100 to 200 lb/a N were similar. Also, increasing N rate from 50 to 100 lb/a increased yield with ammonium nitrate, but urea required 150 lb/a N to increase yield above that of the 50 lb/a rate (Table 1).
Forage N concentrations responded to N fertilizer treatments somewhat differently in the 2 years that subsamples were assayed, so these results are shown by year (Table 2). Nitrogen rate significantly (P<0.05) affected forage N concentration but interacted with application timing in cut 2 of 2008 (factorial means not shown). Increasing the N rate from 50 to 100 lb/a resulted in an increase of forage N concentration in 2006 but not in 2008. In 2006, forage N concentration of cut 1increased as application rate increased from 100 to 150 lb/a N but not with the addition of another 50-lb increment. In cut 2, N concentration was similar with 100 and 150 lb/a N applied, and 200 lb/a N provided a further increase. In both cuttings of 2008, average forage N concentration increased as N rate increased from 100 to 150 lb/a and increased again as N rate increased to 200 lb/a.

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 Southwest Research-Extension Center. Fertilizer treatments initiated in 1961 are 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 zero 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 are broadcast by hand in the spring and incorporated before planting. The soil is a Ulysses silt loam. The corn hybrids [Pioneer 33R93 (2001 and2002), DeKalb C60-12 (2003)

Results
Corn yields in 2009 were greater than the 9-year average ( Table 1). Nitrogen alone increased yields 60 bu/a, whereas P alone increased yields 25 bu/a. However, N and P applied together increased corn yields up to 150 bu/a. Only 120 lb/a N with P was required to obtain greater than 90% of maximum yield, which is similar to the 9-year average. Corn yields in 2009 (averaged across all N rates) were 11 bu/a greater with 80 than with 40 lb/a P 2 O 5 , which is greater than the 9-year average.