4/12/2014 7:00 AM
By Deborah Jeanne Sergeant New York Correspondent
Can producers reduce tillage in an organic cropping system and still be able to control weeds? It’s one of the questions a group of farmers and researchers is trying to answer.
A Tuesday webinar through eOrganic, “Putting the Pieces Together: Lessons Learned from a Reduced-Tillage Organic Cropping Systems Project,” included experts from Penn State who shared information from a three-year study on reduced-tillage organic cropping systems.
Tuesday’s webinar included research from Penn State, the USDA Agricultural Research Service, or ARS, in Maryland, the University of Delaware and North Carolina State University, on the Reduced-Tillage Organic Systems Experiment, or ROSE, which is taking a look at integrated pest management, or IPM, strategies and transitioning to an organic, rotational, no-till system.
Cornell University, Oregon State University, Penn State Cooperative Extension and the National Institute of Food and Agriculture are also involved in the research.
A group of farmers including Elvin Ranck and Kirby Reichert from Pennsylvania, Aaron Cooper and Eddie Taylor from Maryland, and Rob Foscue and Ben and Kenny Haines from North Carolina, were also involved in the project.
Williiam Curran, professor of weed science at Penn State, talked about the Mid-Atlantic region’s ag opportunities. The area boasts diverse agricultural operations, high-density animal agriculture and an enthusiasm for no-till methods, cover crops, sustainable agriculture and organic growing methods.
“Maryland has a very successful cover crop program,” Curran noted.
He believes that in organic grain production, tillage is essential for weed control, incorporating fertility sources, controlling insects and diseases, and terminating perennials and green-manure cover crops. But reducing the need for tillage in organic crops provides benefits, such as protecting against erosion.
“You’re primarily saving diesel fuel costs and labor with reducing tillage,” Curran said. “There are potential barriers or else everyone would be doing this.”
These include a shorter growing season, effective weed control and the ability to control insect and invertebrate pests.
“In these more northern climates, the window for opportunity for establishing cover crops is more narrow,” Curran said. “It’s also hard to maintain good weed control. In annual row or grain crops, no-till isn’t realistic at this time.”
The research team used roller crimpers to see if it would help them manage cover crops in an organic growing system on trial farms in Pennsylvania, Maryland and North Carolina. They based the ROSE system on a three-year rotation of corn, soybean and wheat with cover crops of hairy vetch, triticale, cereal rye, winter wheat, no-till corn and no-till soybean. The roller crimper wasn’t able to penetrate the cover crop and soil sufficiently.
John Wallace, a post-doctoral research associate at Penn State, outlined the research team’s expectations.
They expected that “the window for effective cover crop termination using the roller crimper is sufficiently wide to enable delayed cash-crop planting.”
The team concluded that for hairy vetch, the period between fully flowering and early pod set was the optimal termination point.
“This transition between different growth stages to flowering coincides with a period of rapid growth with hairy vetch in late spring to early summer,” Wallace said. “As you accumulate more biomass, that leads to larger weed suppression.”
You need to plan “your termination where you can get adequate control with obtaining sufficient biomass to suppress weeds,” he added.
Cereal rye offered the additional challenge of unnoticeable flowering.
“Based on experience in the first year, we decided two passes were needed to maintain control,” Wallace said. “They were made two weeks apart.”
The team still experienced volunteer plant growth.
“We have a pretty narrow window in which we can control cover crops with the roller crimper,” he said. “If you roll too early, you have re-growth. If you roll too late, you may get effective termination of cover crops and not much re-growth, but they may become a volunteer issue later in the rotation.”
The team also expected that standard no-till equipment would work for establishing organic cash crops. That proved inaccurate. Modifications enabled the equipment to slice through the high-residue environments that were either too wet or too dry. The modifications included extra weight for seed placement, closing-wheel adjustments and a ripple style coulter, which “is more effective for a more narrow furrow,” Wallace said.
“This is fairly straightforward, but the variably across the sites and years is due because of poor population establishments and not necessarily because of weed or insect pest problems,” he said.
The team’s third expectation was that delayed planting would suppress weeds, thanks to the cover crops. The results showed that “cover crop biomass accumulation did not increase linearly with delay in planting date, already near the peak at termination one,” he said.
The fourth expectation was that supplemental weed control would be necessary to maintain high levels of weed control.
“We found that shallow high-residue cultivator very effective at reducing weed biomass,” he said.
The team observed improved yields where weed competition was high, such as Delaware, but cultivation was not necessary where weed competition was low, such as Pennsylvania, and it can hurt soybean yield.
“Cultivation consistently lowered weed biomass compared with other no-till methods,” he said.
The team also expected that delaying planting would decrease crop injury related to early season pests, such as black cutworms. The results showed that pests could not reach damaging levels, thanks in part to pest predators that increased each year of organic management.
“There were pretty high numbers of predators at our sites,” he noted.
Ron Hoover, senior project associate at Penn State and coordinator of the On-Farm Research Program, commented on challenges to making rotational no-till work in the Mid-Atlantic. These include excessive amounts of rolled cover crop to slice through and cover crops that had blown down and not rolled in an organized fashion.
He believes that they keys to growing sufficient cover crop are starting early and the plants’ inherent fertility.
Curran summed up the results-to-date of the study, though he noted that the team is still compiling data.
The team believes that crop yield, while variable across years and sites, offered acceptable levels. Soybeans were at 70 bushels per acre, corn grain at 140 bushels per acre and corn silage at 18 tons per acre. The team controlled perennial weeds well, but annuals required additional control efforts.