2019 Kansas State University Industrial Hemp Dual-Purpose and 2019 Kansas State University Industrial Hemp Dual-Purpose and Fiber Trial Fiber Trial

Hemp is a broad term used to describe the many varieties of Cannabis sativa L. that produce less than 0.3% tetrahydrocannabinol (THC). The crop is globally significant, but only recently allowed to be grown again in the United States. Varieties that have numerous industrial uses have been selected for improved fiber and grain production. However, there is no information available regarding adaptability or production of these varieties in Kansas. In 2019, Kansans were allowed to apply for research licenses to grow industrial hemp. It was assumed the crop would grow well throughout Kansas since there are wild remnant populations of C. sativa flourishing at numerous locations across the state. However, controlled variety trials are necessary to determine which varieties are best adapted to the state. Currently, farmers must rely on information generated from other states with vastly different growing conditions than Kansas. Variety selection is vital in hemp production considering latitude (day length) and length of growing season influence planting time, number of days to harvest, and ultimately yield. The objective of this study was to evaluate commercially available varieties of industrial hemp in south central Kansas.


Introduction
Hemp is a broad term used to describe the many varieties of Cannabis sativa L. that produce less than 0.3% tetrahydrocannabinol (THC). The crop is globally significant, but only recently allowed to be grown again in the United States. Varieties that have numerous industrial uses have been selected for improved fiber and grain production. However, there is no information available regarding adaptability or production of these varieties in Kansas.
In 2019, Kansans were allowed to apply for research licenses to grow industrial hemp. It was assumed the crop would grow well throughout Kansas since there are wild remnant populations of C. sativa flourishing at numerous locations across the state. However, controlled variety trials are necessary to determine which varieties are best adapted to the state. Currently, farmers must rely on information generated from other states with vastly different growing conditions than Kansas. Variety selection is vital in hemp production considering latitude (day length) and length of growing season influence planting time, number of days to harvest, and ultimately yield.
The objective of this study was to evaluate commercially available varieties of industrial hemp in south central Kansas.

Methods
Research plots were prepared at the Kansas State University John C. Pair Horticultural Center near Wichita, Kansas. The location is a flat sandy loam soil (Canadian-Waldeck fine sandy loam) averaging 32 in. of precipitation annually. The experimental plot had been buffalograss for the previous 12 years. In fall 2018, buffalograss was terminated with glyphosate in preparation for spring 2019 hemp planting. Prior to planting in spring 2019, the plot was cultivated to incorporate remaining surface organic matter. On June 12, 2019, 100 lbs/a of nitrogen (46-0-0) was broadcast then incorporated with a spring-tooth harrow. On June 13, 2019, 14 varieties of dual-purpose industrial hemp (Table 1) were seeded at a rate of 30 lbs of live seed/a (Fig 1). On the same day three varieties of fiber hemp were seeded at a rate of 60 lbs of live seed/a (Table 2). Experimental plots were 4.5 ft × 22 ft and seeded to a depth of approximately 1.0 in. with a Hege 1000 drill outfitted with a Zero-Max gear box on 9-in. row spacing. On June 15, 2019 the plot received 2.5 in. of heavy precipitation causing water to stand in portions of the plot and the soil surface to crust. No germination was observed from this planting.
On June 26, 2019, the experimental plot was cultivated with a drag harrow to break the crust and an additional 50 lbs/a nitrogen (46-0-0) was broadcast and incorporated. The plot was re-seeded with the same varieties, at the same rates, and in the same plots as the previous planting. At this planting, seed depth was adjusted to 0.5 in. Additionally, because of limited seed supply, the variety 'Hliana' was not included in this second planting. On June 29, 2019, the experimental plot received 1.75 in. of precipitation causing some ponding of water, however, germination was considered acceptable to continue the evaluation. Overhead irrigation was applied as needed throughout the summer to prevent drought stress.
From September 4-12, 2019, two 1.0-m 2 sub-plots were chosen randomly for harvest in each experimental plot. For grain yield, the terminal female inflorescence (Fig 2) and primary lateral female inflorescence were removed from the plant and placed in paper bags and weighed (fresh weight). Bags were then air dried for 7 days at 75°F and 45% relative humidity. Once dried, grain was manually threshed, then separated from the chaff by winnowing. Plants within each sub-plot were cut at the soil surface for data collection. Data collected included: plant count per sub-plot, plant height (measured from the soil surface to the point where the female inflorescence was removed from the plant), stem caliper (measured at the soil line), stem fresh weight, and stem dry weight. Dry weight was obtained after drying samples in a forced air drying oven at 160°F for four days.
Fiber varieties were harvested after the grain harvest was complete. Similarly, two 1-m 2 sub-plots were chosen randomly for harvest in each fiber experimental plot. Plants within each sub-plot were cut at the soil surface for data collection. Data collected included: plant count per sub-plot, plant height (measured from the soil surface to the end of the terminal inflorescence), stem caliper, whole plant fresh weight, and whole plant dry weight.
The experimental design for the dual-purpose varieties was a randomized complete block design with 13 varieties. Two subsamples per plot were harvested and the experiment was replicated four times. Data were subjected to ANOVA and means separated by Fisher's protected LSD. An identical experimental design and analysis was employed for the three fiber varieties.
To assess industrial hemp's impact on soil water content we measured the soil profile water content change over the growing season in unirrigated plots of three varieties (Canda, Joey, and Tygra). We also measured the soil profile water content change in unirrigated vs. irrigated plots of one fiber variety (SS Beta).

Industrial Hemp Research 2019
Soil cores were extracted to a depth of 5 ft from areas with a uniform hemp stand in each plot at early vegetative growth (July 23) and soon after biomass sampling (September 20). Gravimetric soil water content (0 g) was calculated for each foot increment in depth at each date as follows:

g = mass of water mass of dry soil
Change in soil water (Δ0 g) was calculated as the difference between the soil water content after harvest and the soil water content at early vegetative stage: Values for Δ0 g were subjected to analysis of variance and mean separation at α = 0.05. In addition to the previously mentioned data, the terminal 20 cm of five plants selected at random were collected from each variety of three replications. The plant material was analyzed for THC and cannabidiol (CBD) content at the Kansas State University Olathe Post-Harvest Physiology Laboratory using accepted laboratory techniques for such analysis.

Results and Discussion
The growing season of 2019 can be summarized as cooler and wetter than normal (Fig 6). The first planting of dual-purpose industrial hemp failed to emerge due to a heavy rainfall shortly after planting. This caused water to pond on the plot and the soil to crust. Germination was near 0% across all plots. The second planting was successful and data were collected at the end of the growing season. Although a rainfall occurred 2 days after planting, it did not prohibit germination and seedling emergence of most varieties. Unfortunately, germination and establishment of varieties Canda, Futura 75, Joey, and Katani were determined to be unsatisfactory to collect reliable data. Additionally, due to limited seed supply, there was insufficient seed to replant Hliana. Therefore, growth and yield data were only collected on the varieties listed in Table 3. However, samples of all varieties were collected for THC and CBD analysis and are presented in Table 5.
Growth and yield were highly influenced by variety in this experiment (Table 3). Fedora 17, Felina 32, and USO 31 had good seedling emergence and early stand development with greater than 100,000 plants per acre. The remaining varieties were all less than 75,000 plants per acre. Helena was the tallest and produced the greatest stem dry weight, overall yield, and individual plant yield, although it had one of the lowest established stands. Felina 32 had one of the highest stand establishment rates and was one of the highest yielding varieties. CFX1 and CRS1 both initiated flowering at approximately 18 in. tall. This is likely due to the late planting date. These varieties are adapted to the long summer days of northern latitudes. It is likely that an April or May planting date would yield much taller plants that are more suitable to a dual-purpose cropping system. However, overall yield of CRS1 was comparable to several of the taller varieties.
In general, fiber varieties were more vigorous (growing faster and ultimately taller) than the dual-purpose varieties (Table 4). SS Beta had the greatest number of plants per plot and also surpassed 2 tons of dry matter per acre. There was no difference in height among the varieties at harvest, however, Fibranova had a greater stem diameter, which may be a result of fewer plants per plot. Eletta Campana had a similar dry weight as SS Beta with a stem diameter between the other two varieties. Stem diameter is an important factor to consider in fiber varieties, because it influences the ratio of bast to hurd fiber.
Soil profile water content data indicated a slight difference among the three unirrigated varieties in the top 1 ft (Fig 4). At depths 2-5 ft there was no difference in soil water content between the varieties. Data from the unirrigated and irrigated fiber plots indicated no difference in soil water content at either depth (Fig 5). These data are not entirely surprising given the amount of precipitation received prior to planting and after planting. During the initial soil core sampling on July 23, free soil water was observed at a depth of 4 ft.
The quantity of CBD and THC in the inflorescence was impacted by variety. None of the varieties in this trial produced enough CBD to be commercially viable (Table 5). Eletta Campana and Fibranova had the highest levels of CBD (1.9%) while the concentration in some varieties was near 0% (Hlesia, Hlukhivs'ki 51, USO 31). Fortunately, none of the varieties produced greater than 0.3% THC, with several producing no or undetectable quantities. Interestingly, the fiber varieties contained more cannabinoids (CBD and THC) than the dual-purpose varieties. At the time female inflorescences were harvested for cannabinoid concentration, dual-purpose varieties were full of mature grain, whereas fiber varieties had less grain population. This may explain the higher cannabinoid concentration in the fiber varieties.
Although data were not collected, significant pests were noted throughout the growing season. There was a heavy presence of spotted cucumber beetle early in the season. Damage was mostly cosmetic and restricted primarily to foliar feeding. Later in the season an extremely heavy infestation of aphids (species undetermined) was observed on leaves and inflorescence. While there was no way to determine potential loss of vigor and yield due to aphids, the overwhelming presence likely had an impact. Accompanying the aphids was an equally heavy presence of ladybugs. As the grain matured, a population of caterpillars were observed feeding in the inflorescence.
This was the first year of industrial hemp research in Kansas and there is a great need for further variety and production based research. This growing season was unusual with frequent precipitation, and lacked extended periods of hot temperatures. Conducting this research under more typical conditions will be necessary so Kansas farmers can make informed decisions when selecting industrial hemp varieties for their farms. In our trials, seed availability and frequent spring rains prevented planting at the ideal (mid-May) time. As a result, our plants failed to achieve the anticipated height and possibly yielded less grain than they would have if they were taller with more branching inflorescences. With no insecticides or herbicides available, the impact of those pests will be difficult to determine. However, there is little doubt that insect pests and weed pressure will continue to be problematic and ultimately impact yield.
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.