Cover crops and landscape positions mediate corn–soybean production

Authors: SINGH, GURBIR - Mississippi State University; DHAKAL, MADHAV - Mississippi State University; SHARMA, ARUN - Mississippi State University; SCHOONOVER, JON - Southern Illinois University; WILLIARD, KARL W - Southern Illinois University; KAUR, GURPREET - Southern Illinois University

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2022
Publication Date: 4/12/2022
Citation: Singh, G., Dhakal, M., Sharma, A., Schoonover, J.E., Williard, K.J., Kaur, G. 2022. Cover crops and landscape positions mediate corn–soybean production. Agrosystems, Geosciences & Environment. 5(2):e20249. https://doi.org/10.1002/agg2.20249.
DOI: https://doi.org/10.1002/agg2.20249

Interpretive Summary: Ecosystem services and cash crop benefits provided by cover crops (CCs) can be affected by field variability as characterized by the topographic positions. A watershed-scale study was conducted during 2015 - 2019 to assess the influence of cereal rye and hairy vetch CCs and topography (shoulder, backslope, and footslope) on corn and soybean rotations in southern Illinois. It is undoubtedly true that cover cropping can benefit crop production in various ways, but care should be given in selecting a type of CC and landscape position. Cover crop biomass, nitrogen uptake, and soybean/corn grain yield were affected by the topography. Cereal rye can provide ground cover by producing significant aboveground biomass at the shoulder and backslope positions than at the footslope region due to gradients in soil moisture and nutrient condition. But it did not add yield benefit to the soybean when compared to no-cover treatment at the backslope and footslope positions. Results showed that the cereal rye – soybean rotation would be ideal for the shoulder position. However, with proper drainage, if the cereal rye biomass increases on the footslope, it could potentially increase the soybean grain yield, as indicated by the linear relations between CC biomass and grain yield. It was evident that the hairy vetch – corn system can increase grain yield significantly over no-CC rotation on shoulder and backslope positions, but not on the footslope. Again, the major concern at the footslope was the establishment of the CC, which is also limiting the subsequent cash crop yield. Strategies that allow CC grow longer period at the footslope would increase its biomass and cash crop yield. Our study suggests that the legume CC should be planted on the shoulder and backslope positions, whereas the footslope should have non-legume CC or can be left fallow during winter. Overall, site-specific CC management is critical if the landscape has significant variability in surface characteristics.

Technical Abstract: Ecosystem services and cash crop benefits provided by cover crops (CCs) can be affected by temporal and spatial variability of CC performances as influenced by topographic position of the field. Small plot-scale research may not detect the spatial variability that may have confounding effects on applied treatments. Thus, a watershed-scale study was initiated in 2015 to assess the influence of CCs (cereal rye, Secale cereale and hairy vetch, Vicia villosa) and topography (shoulder, backslope, and footslope) on corn (Zea mays) and soybean (Glycine max) rotations in southern Illinois. In cereal rye – soybean systems (2016–2018), N concentration of winter biomass produced at the shoulder and backslope had more than that in the footslope, however, dry matter yield at the shoulder exceeded both the backslope and footslope by 66 and 53%. The shoulder produced the greatest cereal rye biomass. Soybean biomass, N uptake, and grain yield (> 21%) at the shoulder and backslope were greater than at the footslope, especially under CC rotation. However, cereal rye CC couldn’t improve soybean yield over no-CC treatment for the backslope and footslope. In hairy vetch – corn systems (2017–2019), hairy vetch CC biomass had three times the N mass of no-CC treatment due to high N concentration in its tissues where the shoulder position yielded significantly greater CC mass and retained the highest amount of N. Cover crops did not affect corn productivity and nutrient composition, but the topography did affect these attributes. Corn yield was greater at CC incorporated shoulder and backslope positions than at the footslope. Cover cropping couldn’t improve soybean and corn yield at the footslope position due to waterlogged condition in the summer. Site-specific CC management is critical if the landscape has significant variability in surface characteristics.