Interseeded cover crops in wide-row corn: An opportunity for northern cropping systems

Cover crops are an effective way to reduce soil erosion and promote soil health. However, in North Dakota and other northern climates where corn (Zea mays L.) is an important commodity crop, killing frosts generally occur before harvest, leaving little opportunity for cover crop planting. By interseeding cover crops into corn during the growing season, the cover crops are given a longer period to establish. The purpose of this study was to identify the impact cover crops interseeded into wide-row (60-inch) corn have on soil water content and corn productivity. Two experimental sites were established in 2020 near Leonard and Rutland, ND. Both sites were organized into randomized complete block designs, with three cover crop treatments in Leonard (n = 9) and four cover crop treatments in Rutland (n = 16). Cover crops were no-till drilled into the corn at the V4 growth stage. The cover crop treatments were diverse mixes developed to either provide pollinator habitat, overwinter, or winter-kill. Throughout the growing season, soil gravimetric water content and cover crop biomass was monitored. At the end of the growing season, dry cover crop biomass ranged from 189 to 1445 lb ac-1. The presence and type of interseeded cover crops did not have a statistically significant effect on soil water content or corn yield. It is suspected the above average precipitation during the month of July led to adequate amounts of soil water for the entirety of the cover crop growing season, limiting the difference between treatments. Northern climate corn farmers face challenges with soil erosion and need to improve soil health. Planting cover crops can help, but short growing seasons in places like North Dakota makes it difficult. One way to establish cover crops in areas with short growing seasons is interseeding-planting the cover crop between rows of corn as it grows. Corn is typically planted with a 30-inch row spacing, which provides full canopy cover and shading of the soil surface, which limits the growth of interseeded cover crops. Increasing the row-width to 60 inches allows more sunlight to reach the cover crop. This study was carried out at two sites in North Dakota and showed interseeding cover crops into 60-inch corn did not significantly affect soil moisture or corn yield. This insight can guide farmers in making informed decisions about sustainable farming practices.