Finding alternatives to plant cover crops02/04/2019 | Crop Production Research, Soil Health
By Carol Brown, ISA environmental communications specialist
With Iowa in the depths of winter, picturing green fields of cover crops may be a welcome thought.
The Iowa Soybean Association (ISA) is in the middle of a three-year research project exploring seeding methods of a cereal rye cover crop. Through this project, ISA researchers are working with farmers to use existing planting equipment for fall seeding of cover crops. The study also looks at planting cover crops in wider rows to minimize risk to corn planting the following season.
“Many Iowa farmers may not have equipment dedicated for planting cover crops nor the means to pay someone else to drill or aerially seed them,” said Theo Gunther, ISA Environmental Programs and Services resource management specialist. “If farmers can use their existing corn and soybean planters to get cereal rye in the ground, it could remove a barrier to not using cover crops. In addition, the controlled placement of the cover crop offset from the planned corn row can potentially help minimize risk to corn yield the following season.”
The first year of data has been processed and the second year of cover crops were planted this past fall. After this year’s crop season, the final cover crop rotation will be planted next fall for this study.
Jon Bakehouse, a corn-soybean farmer near Hastings, is participating in the study. He’s been using cover crops in various forms for 10 years.
“We normally don’t plant cover crops after soybean harvest, so this gave us the opportunity to do that using our planter,” said Bakehouse. “I had noticed some antagonism between the cereal rye and the corn following corn cash crop, so I was really interested in this idea of off-setting the corn rows.”
Cover crops have several benefits, including reducing the risk of nitrogen loss, improving infiltration and aggregate stability. All of these contribute to the goals of the Iowa Nutrient Reduction Strategy, which calls for a 45 percent reduction in nitrogen and phosphorus entering Iowa’s waterbodies. Cover crops can reduce nutrients leaving fields by an average of 30 percent.
Bakehouse uses cover crops to combat erosion on his flat, poorly drained soil, with the goal of keeping the ground covered for as many days as possible, as well as a keeping living root in the soil for as long as possible.
“I believe in the Nutrient Reduction Strategy and about being proactive about water quality downstream. Cover crops help with that, too,” Bakehouse said.
The project involved eight farmers across the state, planting cereal rye in the fall followed by corn rows planted between the rye rows. The cooperators tested a combination of no rye controls, twin row, 15-inch and 30-inch rye, and some in combination with termination timing or strip-tillage treatments.
Researchers are looking at comparisons of several measurements including surface biomass, early season soil nitrogen, yield, and end-of-season corn stalk nitrate. These can show the potential of this method to reduce risks and offer another establishment option for farmers.
Although only one year of data has been processed, results have been mixed. Bakehouse experienced considerable yield drag in his corn crop but said some of it could be attributed to the weather.
“We had a really cold, wet spring and a really wet fall, so we expected some yield drag,” he said.
Gunther said this offset method shows potential for offering a longer window of cover crop growth in spring, but more data is needed to determine whether rye termination timing can be safely modified, or the separation of rows provides a great advantage.
“If planting conditions are favorable, yet the cover crop has not been terminated by the recommended several days in advance, an intentional gap in the cover stand can allow for timely planting,” Gunther said. “A traditional solid stand of rye might not be ready when planting time is right.”
But this past fall was not an ideal year for cover crops. With the wet fields and late harvest, many farmers weren’t able to get cover crops planted. Gunther said there will be fewer fields to use in their comparisons, but they will collect what data they can. Bakehouse got his cereal rye planted last fall in between the rain showers and is optimistic for yield improvement this coming crop season.
Cover crop success will always depend on the goals the farmer has for using them. If the difference between seeding and not seeding is available equipment, using an existing planter can be an option. If the next crop is corn, offsetting the cover crop to reduce competition in the corn row may be worthwhile.
Farmers who seeded cover crops last fall with a skip row drill, used 15-inch spacing, or had an arrangement that leaves a gap for the following corn or soybean row, are encouraged to contact Gunther (email link) to participate in testing for the 2019 season.
“I know there are individuals out there with previous cover crop experience or who are currently trying these seeding methods. Projects like these help us gather and share increased knowledge to help farmers make better decisions,” he said.
The project is funded through a grant by the Leopold Center for Sustainable Agriculture at Iowa State University (ISU), now managed through the Iowa Nutrient Research Center at ISU.
Contact Carol Brown at firstname.lastname@example.org
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