Investigation of short-term effects of winter cover crops on compaction and total soil carbon in a long-term no-till agricultural system

Abstract

Implementation of winter cover crops (CC) is a conservation practice aimed at improving soil health and increasing water infiltration. Reduced tillage (e.g., no-till), another, more common conservation practice, shares these aims. While the literature concerning the main effects of CC and reduced tillage is rich, the additive effects of CC and reduced tillage are unclear and understudied—specifically, the adoption of reduced tillage long before (20+ years) CC implementation, which is common in the last half-century. This study assessed two of the potential short-term effects of CC when added in a long-term no-till system: reduction of soil compaction (SC) and addition of soil total carbon (STC). Four field plots in northeast Mississippi were planted with CC while two were utilized as controls having no CC. All plots were under no-till for the last 20+ years. Soil penetration resistance measurements (SC) and soil cores were collected in April of 2017, following two years of CC implementation, from 20 semirandomly selected locations in each plot. Model comparisons were used to explore variation in SC and STC between CC and control plots, and the contributions of covariates to the observed variation. Results of the selected models (model with highest Akaike's weight) indicated there was no difference in SC between CC and control plots; however, slight variation in STC did exist between the two treatment levels (d ± 95% CI = 0.46 ± 0.39, p < 0.05). Cover crops explained ≃0.7% and ≃5.0% of the variation in SC and STC, respectively. Results showed that soil moisture and unidentified field-scale variables (plots were divided between two adjacent fields) explained an additional ≃20% of the variation in SC and ≃13% in STC. The results in this study suggest that the addition of CC in a long-term no-till system helps to conserve STC over a shorter period than previously expected. Further investigation with more control in the experimental design is needed to better understand how the addition of CC to long-term no-till systems may compound benefits, lead to better management, and, potentially, increase adoption by producers.