Interseeding Cover Crops

In early 2020, the Allamakee County Soil and Water Conservation District was awarded $235,907.00, for a three-year project, that involves interseeding cover crops into V4-V7 Corn. The funding for this project came from the USDA Conservation Innovation Grant (CIG) program.

 Short planting windows after commodity crop harvest has some producers frustrated and looking at other methods of getting cover crops established. One option is interseeding cover crops into corn between the V4-V7 growth stages. Doing this allows cover crops to get established prior to corn canopy.  After canopy, the cover crop will go dormant from being shaded out and then restart growth once the corn is harvested. The overall goal of this project is to get more producers to try interseeding as an option for cover crop establishment.

Sixteen participants throughout Allamakee County have their plots planted. They used several different seeding methods including no-till drills, broadcast spreaders, Monosem planter, and a couple different custom air seeders. Each grower chose from four different seed mixes including species such as rye grass, buckwheat, brassica, and cow peas.  A minimum of four replicated strip trials were completed at each site. The main components of the project will be evaluating yield, cover crop biomass, nutrient uptake, soil microbiology, and soil loss. Temperature loggers have been installed in interseeded and non interseeded rows with each participant to gauge season long differences in soil temperature. Haney soil tests will be run for every producer and if they continue for multiple years will be used again to gauge any soil health improvements.

Mark Stock, who farms near Waukon, planted the four species mix (ryegrass, buckwheat, cowpea and brassica) into V5 corn on June 19th. He used a custom air seeder which he recently built for the project. It was constructed from a Gandy air seeder box and a cultivator tool bar. He then added single disc fertilizer openers to incorporate the seed into the soil. The overall width of the seeder is thirty feet and it has folding wings for transport. Mark intends to also use the seeder as part of a relay crop system where he plans to fall seed rye then plant soybeans between in the spring