Interseeding cover crop into an irrigated sandy loam for 6 years: Soil, crop, and economic response

Authors: BLANCO-CANQUI, H - University Of Nebraska; Ruis, Sabrina; MAMO, MITIKU - University Of Nebraska; SHAPIRO, CHARLES - University Of Nebraska; PROCTOR, CHRISTOPHER - University Of Nebraska; PARSONS, JAY - University Of Nebraska; THOMPSON, LAURA - University Of Nebraska

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2024
Publication Date: 1/19/2025
Citation: Blanco-Canqui, H., Ruis, S.J., Mamo, M., Shapiro, C.A., Proctor, C., Parsons, J., Thompson, L. 2025. Interseeding cover crop into an irrigated sandy loam for 6 years: Soil, crop, and economic response. Agronomy Journal. 117(1). https://doi.org/10.1002/agj2.70013.
DOI: https://doi.org/10.1002/agj2.70013

Interpretive Summary: Cover crop benefits to soils and crops depend on cover crop biomass production. In the U.S. Corn Belt, cover crops are typically drill-planted in fall after crop harvest and then terminated in early spring. Broadcast interseeding cover crops into corn or soybean one or two months prior to harvest could increase the duration of optimum growing conditions for cover crops. We tested how broadcast interseeding a winter rye cover crop affected soils, crops, and farm income compared with drilling cover crops after harvest. The experiment was conducted for six years in an irrigated no-till corn-soybean rotation. Interseeding the cover crop slightly increased cover crop biomass yield compared with drilling (0.57 vs 0.37 Mg/ha). Interseeding the cover crop had very limited effects on fresh and total C contents, soil structure, nitrate leaching, and crop yields compared with drilling cover crops. As expected, both cover crop planting methods reduced farm income compared with no cover crop due to costs associated with planting the cover crop. Even though at this site interseeding did not significantly improve soils or crop biomass yields, interseeding could outperform drilling at other sites with different environmental conditions. In addition, more years of cover crops may be needed to detect changes in soil properties in this sandy soil. These findings are important to farmers, scientists, and others who want to understand cover crop best management practices with potential to enhance the sustainability and productivity of sandy soils.

Technical Abstract: Interseeding cover crops (CC) may boost CC biomass production and enhance soil and crop benefits relative to the traditional CC planting system (post-harvest drilling), but data for comparing these two CC management strategies are limited. We conducted an on-farm experiment for 6 yr to study how broadcast interseeded (32 to 67 d before crop harvest) winter rye (Secale cereale L.) CC affected CC biomass production, soil properties, nitrate leaching potential, crop yields, and farm income compared with post-harvest drilled CC in an irrigated no-till corn (Zea mays L.)-soybean (Glycine max L.) rotation in a sandy loam in the western U.S. Corn Belt. Across years, interseeded CC produced 0.57 Mg ha-1 of biomass, while post-harvest drilled CC produced 0.37 Mg ha-1. Interseeded CC did not affect soil properties including particulate organic matter and organic C concentrations, and mean weight diameter of water-stable aggregates compared with post-harvest drilled CC. Nitrate leaching is a concern in sandy soils, but interseeded CC had mixed effects on soil nitrate concentration. Interseeded CC did not affect crop yield nor reduce farm income more than post-harvest drilled CC. Both interseeded and post-harvest drilled CCs had minimal effects on soils and crops, which are attributed to the low CC biomass (<1 Mg/ha) production. A need exists to identify additional strategies to further boost CC biomass production and thus soil services in this region. After 6 yr, interseeded CC slightly boosted CC (by 0.22 Mg/ha) biomass production but had minimal effects on soils and crops, although both interseeded and post-harvest-drilled CCs reduced net income.