Cover crop residues may be beneficial for retaining soil moisture and suppressing weeds, but these residues can also cause impact planting and germination of the subsequent cash crop. We have occasionally observed issues with reduced cash crop stands in our research studies, particularly when planting green into high biomass cover crops.
For example, we noted a reduction in corn stand counts with increasing cover crop biomass (lb/acre; Figure 1). While there was high variability in stand counts across all plots, we saw a trend for a reduction in corn stand counts when cover crop biomass exceeded 2,500 lb/acre, which was the average cover crop biomass measured in our study (Figure 1, Red X). Based on data collected across DE in 2021 (Figure 2), we noted that cover crop biomass reached 2,500 lb/acre when cover crops were terminated at or after April 29. Based on our past results, we suggest growers consider termination of actively growing cover crops before the end of April to prevent issues with corn germination and stand establishment. As always, we recommend growers use their best judgement based on past results.
Figure 1. Cover crop biomass impacted corn stand establishment in 2021 UD Field trials, especially when cover crop biomass exceeded 2,500 lb/ac (Denoted by the red X).
Figure 2. Cover crop biomass increased with later termination timing in 2021 UD field trials. By 29 Apr 2021, cover crop biomass in most plots was >2,500 lb/ac, which may negatively affect corn germination and establishment.