Hemp Production for Fiber or Grain - Revised
University of Nebraska-Lincoln Extension information is typically based on the interpretation of research information from Nebraska or elsewhere in the Midwest. However, such information is not available for hemp production due to previous restrictions on research in the U.S. This publication relies heavily on research findings from Europe and Canada. See more stories in this series at https://cropwatch.unl.edu/tags/hemp.
In Nebraska, hemp grown for fiber or grain will more closely match existing cropping systems than hemp grown for CBD. Fiber/grain hemp could increase diversity for current rotations, but may offer some challenges, given no pesticides are currently labeled for pest management. Hemp production for fiber and/or grain can be highly mechanized with labor demands per acre similar to that of other agronomic crops, except for weed control and harvest operations which require relatively more time for hemp.
Seed sources and varieties
Varieties of hemp, whose stems are used for fiber, bio-fuel, or other products, grow to 6-7 feet in height, providing the desired long fibers for industrial processing. Varieties such as Futura 75, Futura 77, and Fanola have had some validation for Nebraska conditions. Hemp varieties should be certified as having <0.3% THC. Earlier maturing varieties may be preferred for grain production, and in some instances, they may be desired for both grain and fiber harvest. Fiber yield is likely to be less with earlier-maturity varieties than later-maturity varieties because cellulose concentration and yield increase as the season progresses. Male plants die off during the season and monoecious female varieties are generally preferred for industrial hemp production.
Grain production may be optimized with no more than 150,000 plants per acre and sowing 20 to 30 lb/ac of seed. Fiber production may be best when planting in row spacings of less than 12 inches, however, some do plant in 30’ rows. The seed rate maybe 25 to 30 lb /ac. High plant density results in tall plants capable of producing longer fibers. Hemp can be sown with a grain drill such as used for wheat. The seed weight has been estimated at 15,000 to 27,000 seed per pound (1000 kernel weight of 18-22 grams; the seed will be smaller for monoecious varieties). The seed is fragile and can be damaged during planting. With air planters, the fan speed should be set at low.
In Europe, fiber yields were not increased by having more than 182,000 plants per acre and this plant density resulted in better quality fiber than with higher plant densities. Hemp plant stands are likely to self-thin as more vigorous plants suppress the less vigorous, such as the male plants. Seed placement should be ½ to ¾ inch deep; some recommend seeding at more than a 1-inch depth in dry soil.
Soil temperature should be about 55 oF. Emergence is likely three to five days after spring planting. Hemp is more tolerant of low soil temperature at planting than corn and while seedlings can be killed by an early frost, hemp survived a 24oF temperature in May in Canada.
Fertilizer recommendations have not been determined for Nebraska. Penn State University has recommended 150 lb/ac N, 30 lb/ac P2O5 and 20 lb/ac K2O. In a series of trials in Europe, mean fiber yield did not increase with when nitrogen was increased from 90 lb/ac to 140 lb/ac; however, in another set of trials conducted in the Netherlands, fiber yield increase as the N rate was increased to 180 lb/ac. In Alberta Canada, grain yield peaked with 110 lb/ac N and fiber yield peaked with 80 lb/ac N. The optimal P and K rates will depend on soil test values.
Weed, Disease, and Insect Management
A list of products allowed for pest control is provided by the Nebraska Department of Agriculture. Weed suppression with narrow rows, high plant density, and tall plants is important for fiber production. If planted in 30” rows, inter-row cultivation may be needed for early weed control. Hemp can be planted no-till following a burn-down application of herbicide.
There is potential for disease and insect pest problems but information and recommendations are lacking for Nebraska and other states. No pesticides are labeled for hemp in the US. Therefore, rotation of hemp with other crops may an important component of integrated insect and disease management for hemp production. Hemp may benefit other crops in rotation such as through suppression of weeds and some nematode species by hemp. In Alberta, gray mold has been a problem and rotation with canola was found to increase sclerotinia.
Grain should be harvested when shattering begins. The rest of the plant will still be green and about 70% of the seed will be mature. The grain water content may be >20% but <20% is desired. Grain combines can be used for grain harvest and some have suggested settings similar to those used for grain sorghum. The long stems can challenge combine harvest so some have placed PVC pipe around moving parts to reduce wrapping. The header should be kept high enough to get the grain while minimizing stem that needs to pass through the combine. The cylinder speed should be 4500-6000 rpm. Much dust can be generated when the plants are dry creating a fire hazard. Move grain at low auger speeds or with conveyor belts to reduce damage.
As with any grain crop, the proper harvesting, processing, transportation, and storage are critical to prevent spoilage and ensure the highest value for the harvested grain. Hemp grain is thin-walled and fragile, requiring care in harvest, storage, and transport. A grain drying facility is needed and grain drying should begin within 1.5 hour of harvest. Drying can be at 140oF with a continuous flow drier but grain temperature should not exceed 100oF to avoid ‘toasting’. Hemp grain, about the size of sorghum grain, contains 29-34% oil of which 15-25% is alpha-linolenic acid (an omega 3 fatty acid) compared with 35-45% oil content for flax of which 70% may be alpha-linolenic acid.
Hemp is swath or windrow cut for fiber production at about 8” between early bloom and seed set when the lower leaves of female plants begin to yellow. The windrows are baled at 12% moisture content and the bales are transported for processing to remove and separate the bast and hurd fibers. Bast fiber concentration is highest in the "bark" of the stem while high lignin but shorter hurd fibers dominate in the rest of the stem. Therefore, wider diameter stems are preferred. Common fiber yields are 15-22% of stem dry weight. A multi-cut combine is available that harvests the upper plant for grain while windrowing the stems; it seems it works well for some varieties but not all. An alternative for harvesting both grain and fiber is to harvest these in separate passes, maybe giving the stems more time to dry before cutting for the fiber harvest.
Information is scarce. We have not learned of any large-scale commercial heap decortication facility operational in US. Small-scale hand-fed equipment is marketed on-line. Canadian Greenfield Technologies has their patient pending HempTrain™ which is described as capable of handling baled hemp feedstock and separation of the high-CBD fraction, green microfiber, bast fiber, hurd, and grain fractions. It is reported to be capable of processing feedstock at 1 t/hr.
Traditionally, hemp was left in the field for up to five weeks after cutting for retting (dew retting), a decomposition process that breaks the bonds between the outer long bast fibers and the inner shorter hurd fibers. However, dew retting is subject to weather conditions and uncontrolled with inconsistent and often negative effects on fiber quality. An alternative to dew retting is water retting which requires much clean water which should be treated before discharge. More common may be mechanical fiber separation without any retting or maybe with an enzymatic treatment.
It appears the 2019 supply greatly exceeded demand and hemp fiber and grain feedstock prices plunged during 2019. The supply/demand discrepancy was greater for the Great Plains compared with some other areas. Rather than outright purchase of feedstock at an agreed price, processors offered growers a profit share arrangement on the product once sold. Available market information is too weak for prediction but indicates a need for caution. Some brokers and processors may be new with little capacity to fulfill obligations under adverse conditions with risks of failed contracts or delayed acceptance of feedstock. See a USDA ERS Feb 2020 report.
Hemp Production Budgets
Questions and Answers
- What are the certification requirements to produce hemp in Nebraska? Nebraska’s hemp regulations have been approved by USDA. Hemp production and processing in Nebraska requires a signed license agreement from the Nebraska Department of Agriculture. Under federal law, industrial hemp must be less than 0.3% THC. The application fee is $100. If approved, a grower will pay $400 and a processor will pay $800 in registration fees.
- What are inspection requirements to ensure less than 0.3% THC concentration? The state will collect random samples from farmer fields within 15 days before the harvest date in the presence of the grower. Samples will be analyzed by a laboratory with US DEA registration and ISO 17025 accreditation.
- What are the marketing opportunities for hemp? Do you need to presell the crop or sell after harvest? The Market is uncertain and production should be under contract with a processor. The decision to pre-sell or hold usually has more to do with financing needs and financial plans of both the farmers and the processors that may commission the crop. Some brokers and processors may be new or financially weak with little capacity to fulfill obligations under adverse conditions with risks of failed contracts or delayed acceptance of feedstock.
- Without a commodity exchange for hemp, it’s hard to know how much one would need to make to at least break even. What are prices like? Are they trending up? Is it possible to be profitable? The 2019 supply appears to have greatly exceeded demand and prices plummeted. Good market information is scarce. However, many crops have been lost to fake science and bad genetics. With such a growth market, farmers need to use proven and certified genetics and proven supply chain networks, realizing that some stakeholders could take unscrupulous shortcuts such as selling inappropriate seed.
- Is crop insurance available for industrial hemp? The USDA Multi-peril Crop Insurance Pilot Insurance Program was initiated in 2020 for 21 states but not for Nebraska. The crop insurance is only applicable with a contract. The Noninsured Crop Disaster Assistance Program “provides coverage against loss for hemp grown for fiber, grain, seed or CBD for the 2020 crop year where no permanent federal crop insurance program is available.”
- Where do you buy hemp seed and other specialized inputs? There are a few good sources of hemp seed. Be cautious and ensure that varieties you’re considering are well adapted with certification for <0.3% THC. For CBD production, validate the feminization of seed as growing only female plants is preferred as pollination leads to seed production and decreased CBD yield.
- Who’s the most likely candidate for hemp production? Adding another profitable crop in your rotation often makes for good agronomy. For those already including small grain or hay in their rotation, production of hemp grain and fiber may not require much additional equipment. Hemp for CBD is a horticultural crop with high labor demand, often with greenhouse production at least for seedling production, and the need for drying facilities.