During 2016, our Northwest Crops and Soils Program began researching industrial hemp. Hemp is a non-psychoactive variety of cannabis sativa L. The crop is one of historical importance in the U.S. and is re-emerging as manufacturers seek it as a sustainable resource for a wide array of food and fiber products.
Vermont is among 32 states allowing hemp production and growers have begun experimenting with it; however, hemp remains mostly prohibited at the federal level. The 2014 Farm Bill has allowed universities, like the University of Vermont, and state departments of agriculture to produce hemp for research purposes. Hemp is poised to be a “new” cash crop, creating a potential market opportunity for Vermont farms. To help farmers succeed with this new crop, regionally adapted agronomic research is needed. In 2016, we performed research trials to evaluate planting dates, varieties, seeding rates, and row spacing for their impact on hemp yield and pest pressure.
Research Trial Results
Planting Dates and Varieties
Twelve varieties of hemp were grown over the course of four planting dates: 26-May, 2-Jun, 12-Jun, and 17-Jun and seeded at 25 lbs ac-1. All hemp varieties at all planting dates reached full maturity. The best time to harvest is when 50% to 70% of the seed is visible and brown; the remaining seed is covered with a green husk that surrounds the seed while it is developing (if the green shell is removed most of the seed is mature). When we harvested past this point of maturity, there were significant seed losses due to bird damage, shatter, and tougher, more mature hemp fiber gumming up the combine. Harvest from the first planting date (26-May) showed optimal yields, averaging 850 lbs ac-1, above the Canadian yield averages of 500 to 1200 lbs ac-1. The 2-Jun planting date averaged a yield of 575 lbs ac-1, the 12-Jun planting date averaged a yield of 407 lbs ac-1, and the 17-Jun planting date averaged a yield of 552 lbs ac-1. Differences in variety performance were observed and can be seen in Table 1.
Three row spacing treatments were evaluated including a STANDARD at 7.0” between rows, WIDE at 9.0” between rows, and a BANDED treatment that created 5” banded seed rows and 6” between rows. The variety Anka was used for this trial and planted on 24-May at 25 lbs ac-1. The WIDE and BAND treatments were cultivated with a row cultivator on the 16-Jun. Weed cover in the treatments ranged from 7.03 to 17.1 percent, which was not significantly different between treatments. Hence, row spacing did not appear to impact weed biomass and cultivation did not appear to improve weed control. In addition, row spacing did not significantly affect yields. Average yields for the trial were 1120 lbs ac-1.
Five seeding rates–20, 25, 30, 35, and 40 lbs ac-1–were trialed over two varieties, Anka and CFX-2, planted on 31-May. Hemp yield and test weight were not impacted significantly by seeding rate. The average yield across all seeding rates was 1140 lbs ac-1. Plant populations measured at harvest were significantly higher for the 35 lbs ac-1 seeding rate at 7.07 plants ft-2 and comparable among all other seeding rates.
We plan to continue this research for the 2017 season. For more information on the results of our 2016 research, please check out our website: uvm.edu/extension/cropsoil/hemp.