Establishment and function of cover crops interseeded into corn

Authors: NOLAND, REAGAN - UNIVERSITY OF GEORGIA; WELLS, M - UNIVERSITY OF MINNESOTA; SHEAFFER, C - UNIVERSITY OF MINNESOTA; COULTER, J - UNIVERSITY OF MINNESOTA; BAKER, JOHN; MARTINSON, K - UNIVERSITY OF MINNESOTA

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2017
Publication Date: 1/4/2018
Citation: Noland, R., Wells, M.S., Sheaffer, C.C., Coulter, J.A., Baker, J.M., Martinson, K. 2018. Establishment and function of cover crops interseeded into corn. Crop Science. 58(2):863-873. https://doi.org/10.2135/cropsci2017.06.0375.
DOI: https://doi.org/10.2135/cropsci2017.06.0375

Interpretive Summary: There is general agreement that winter cover crops can provide a variety of ecosystem benefits in annual row crop systems, but cover crop usage in corn-soybean rotations in the upper Midwest USA is still low. The primary reason for this is that it is difficult to get them established because there is often little or no time for planting and establishment in the narrow window between fall harvest and winter. To address this, we tested three methods for seeding winter cover crops into corn much earlier in the growing season, at the 7-leaf stage. These included directed broadcast into the inter-row (DBC), directed broadcast with light incorporation (DBC+INC), and a high-clearance drill (DRILL). Cover crops tested included winter rye [Secale cereale L. ‘Rymin’], red clover [Trifolium pretense L. ‘Medium’], hairy vetch [Vicia villosa Roth], fieldpennycress [Thlaspi arvense L. ‘MN-106’], and a mixture (MIX) of oat [Avena sativa L.], pea [Pisum sativum L.],and tillage radish [Raphanus sativus L.]. All olanting methods were successful, but the DRILL method produced more fall biomass than DBC for all cover crops except pennycress, and theboth DRILL and DBC+INC both produced more red clover and hairy vetch spring biomass than DBC. The presence of the cover crops did not affect corn yields or yields of the following soybean crop, except in one case where poor termination of hairy vetch reduced yield by 105. We conclude that winter cover crops can be successfully established in young (7-leaf) corn, providing soil protection over the winter without affecting yield of either the corn or the following soybean.

Technical Abstract: Cover crops can provide ecological services and improve the resiliency of annual cropping systems; however, cover crop use is low in corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotations in the upper Midwest due to challenges with establishment. Our objective was to compare three planting methods to establish cover crops (winter rye [Secale cereale L. ‘Rymin’], red clover [Trifolium pretense L. ‘Medium’], hairy vetch [Vicia villosa Roth], field pennycress [Thlaspi arvense L. ‘MN-106’], and a mixture (MIX) of oat [Avena sativa L.], pea [Pisum sativum L.], and tillage radish [Raphanus sativus L.] in corn at the seven leaf collar stage. Planting methods included directed broadcast into the inter-row (DBC), directed broadcast with light incorporation (DBC+INC), and a high-clearance drill (DRILL). The DRILL method achieved greater fall biomass than DBC for all species except pennycress, and DRILL and DBC+INC increased red clover and hairy vetch spring biomass compared to DBC. Cover crops did not affect corn grain or silage yield, and reduced yield of the subsequent soybean crop by 0.4 Mg ha-1 (10%) only when poor termination of hairy vetch occurred at one site. Cover crops with = 390 kg ha-1 of spring biomass reduced soil nitrate N compared to the no cover control. These results support that cover crops can be interseeded into corn at the seven leaf collar stage in the upper Midwest to reduce soil nitrate N while maintaining corn and subsequent soybean yields; however; effective cover crop termination is critical to avoid competition with the subsequent soybean crop.