CHIPPEWA FALLS — The first year of Wisconsin’s industrial hemp pilot program proved a challenge to farmers. This year, more than six times the number of farmers who participated in the inaugural season are hoping to give the crop a try.

In an effort to take some pressure off future hemp growers, the UW-Madison College of Agricultural and Life Sciences and UW-Extension are participating in a statewide project hoping to uncover best growing practices for the crop.

Wisconsin’s industrial hemp program launched in the 2018 growing season with about 250 licensed growers, although many of those did not actually plant a crop. License applications rose dramatically for the 2019 season, largely in response to the new farm bill’s removal of hemp from the controlled substances list. More than 2,000 farmers and businesses have applied to grow or process industrial hemp in 2019, according to the Wisconsin Department of Agriculture, Trade and Consumer Protection.

“There’s lots of interest,” UW-Extension Buffalo County Agriculture Educator Carl Duley said. “But I’m not sure how many people will get seed in the ground.”

Nearly 1,500 farmers applied for licenses to grow hemp in the state this year, up from 260 in 2018. There were also 716 applications for a processing license, up from 107 a year ago.

A difficult growing season, limited seed options and unclear regulations presented obstacles for farmers who jumped at the chance to grow industrial hemp in Wisconsin in 2018.

With test plots going in around the state this year, things could get easier in the future.

Test plots this year in Buffalo and Chippewa counties will include fertilizer trials on different varieties of hemp. They are also doing small plot variety trials and CBD oil variety trials on the Chippewa County plot and larger strip plots in Buffalo County.

The Chippewa County tests will mirror tests being done at UW-Madison’s Agricultural Research Station north of Madison but on Chippewa County’s sandier soils, Duley said.

The UW-Extension testing will include four varieties of the industrial hemp plant: CBD varieties, grain varieties, fiber varieties and multipurpose varieties that produce both grain and fiber.

“We’ll monitor how aggressive (the hemp varieties) are because weed control is a big issue; we’ll monitor disease and insect issues; and at harvest, we’ll evaluate for yield,” Duley said.

The project’s field tests will study the effect various agronomic practices can have on the THC levels in the plants. If the THC concentration rises above the legal limit of 0.3 percent dry weight, the crop must be destroyed, which happened to a number of Wisconsin farmers in 2018, Duley said.

“There’s a concern that adding nitrogen fertilizer — even though the crop uses a lot of nitrogen — raises the THC level,” said UW-Madison master’s student Haleigh Ortmeier-Clarke, who is using the UW-Extension industrial hemp trials for her master’s thesis on the crop. “We want to make sure that doesn’t happen because that would lead to confiscation.”

Duley said much of last year’s CBD oil plantings tested high for THC content. A majority of interest among farmers is from producing the CBD varieties of hemp, he said.

“In my understanding, if you delay harvest, THC goes up,” Duley said. “We had all the rain last year, and people weren’t used to the day it’s due to come off, you have to take it off. Whether it’s raining or not, you just have to.”

Wisconsin was once a leading producer of industrial hemp, primarily for rope production, until it was prohibited in 1938.

Duley said he and UW-Extension Chippewa County Agriculture Agent Jerry Clark decided to do the larger CBD variety trial in Chippewa County to cut down on the likelihood of cross-pollination issues that could affect the THC content of the plants.

“(In Buffalo County,) we have ditchweed everywhere because we had huge bases in World War I and World War II when industrial hemp was everywhere,” Duley said. “Winona, Minn., had the largest hemp processing plant in the country, and it’s right across the river from us.”

For the grain varieties of the industrial hemp test plants, Duley said he would also like to see the plants tested for oil content.

“They’re fairly high, like 35 percent, oil,” Duley said. “It can be used like olive oil for cooking. And it’s really pretty good just as a dipping sauce.”

The state’s industrial hemp program grew out of legislation passed in late 2017 that allowed growing and processing industrial hemp in Wisconsin. The 2014 federal farm bill had authorized states to create pilot research programs that were administered by universities or state agriculture departments.

Prior to the 2018 Farm Bill, industrial hemp was on the federal list of controlled substances because it is the same species as marijuana. Industrial hemp is bred to have very low levels of THC, the psychoactive ingredient in marijuana.

Duley tried a fertilizer trial last year in Buffalo County, but a stretch of 10 chilly, wet days after planting allowed weeds to take over and cost him half the plot.

“That’s the learning process,” Duley said.