Hemp Plots at Rock Springs Photo: Greg Roth, Penn State
In 2017 we obtained a permit from the PA Department of Agriculture to evaluate industrial hemp as a crop and some management variables such as variety, N fertility, planting date, and seeding rate associated with good production practices for hemp grown for seed. Field plots were established at the Russell Larson Research Farm near Pine Grove Mills in Centre County, Pennsylvania using chisel plowing followed by several secondary tillage passes to destroy weeds that emerged over a three week period. Most trials were planted on June 6.
In the variety trial, six varieties from Hemp Genetics International (CFX-2, CFX-1, CRS-1, Picolo, Katani, and Grandi) were evaluated at three planting dates. In general, the taller lines, CFX-2, CFX-1, CRS-1 yielded more (1206 lb/a) than the shorter lines Picolo, Katani, and Grandi (1029 lb/a). This could have been a result of their better competitiveness with weeds in our environment. We planted on June 6, 13 and 21 and yields declined slightly from 1216 to 1078 lb/a with the last planting date. The crop took 82 to 86 days from planting to harvest, so it was a relatively short season crop. As planting was delayed, the plant height was reduced from an average of 36 to 25 inches. We concluded that planting a taller line early is the best way to maximize yield and plant height. Ideally planting one of the taller lines in late May in this area might be ideal.
In the fertility trial, five N rates were applied that totaled 0, 50, 100, 150 and 200 pounds of N applied at planting to the variety CRS-1. Yields in this trial increased from 960 lb/a in the check plots to 1770 at the 100 pound rate and were maximized at the 150 lb/acre treatment at 1850 lb/a.
In the seeding rate trial, five seeding rates of 15, 20, 25, 30, and 45 pounds per acre were evaluated with the varieties CRS-1, Grandi and Picolo. Yields of the taller variety CRS-1 were maximized at 30 lbs/acre while the shorter Grandi and Picolo lines needed 45 lb/acre to maximize yields.
Weeds were one of our biggest challenges. We planted most of the trial in 15 inch rows but had a demonstration area that was drilled in narrow rows. That appeared to help reduce weed pressure. There are no herbicides labeled for hemp in the US so we needed to rely on tillage and competition.
Based on our experience, drilling a taller line at 30 lb/acre in late May and fertilizing with 150 pounds of N might be a good management strategy. We plan to repeat this study again in 2018 with some modifications in the protocol to reflect what we learned in 2017. We will also be conducting an herbicide evaluation.
We also evaluated some no-tillage establishment and that appeared to work well. We harvested the crop with a non rotary combine and did not have any problem. Some other permit holders reported problems with harvesting taller varieties, especially with a rotary combine.
We concluded management details are important and that it should be possible to grow yields of 1500 to 2000 lb/acre of seed with good management. Hemp can also be grown for fiber and cannabinols (CBDs). When growing for these end uses, different management tactics need to be deployed.