Spatiotemporal changes in soil chemical properties when cover crops are integrated into raised, stale seedbed corn production systems

Abstract

Commercial row crop production in the midsouthern United States is characterized by extensive application of inorganic soil inputs and management practices that contribute to degraded soil health. This study was conducted to determine if cover crops affect spatial or temporal changes in soil chemical properties in a raised, stale seedbed tillage system common to the midsouthern United States. The effects of cover crop, depth in soil profile, and time on soil organic matter, nitrogen, carbon, and phosphorus content and distribution in a corn [Zea mays (L.)] production system were investigated at Stoneville, MS, on a Commerce very fine sandy loam (a fine-silty, mixed, superactive, nonacid, thermic Fluvaquentic Endoaquept). All cover crops increased soil organic matter content 6%–12% relative to the no cover crop system. Except for tillage radish (Raphanus sativus L.), seeding a cover crop increased total N and total C content up to 12% throughout the soil profile. Conversely, grass and brassica cover crops decreased Mehlich-3 extractable P by 18% at 15- to 30-cm deep in the soil profile but did not differ from winter fallow above 15 cm. Cover crop did not interact with either year or sampling time (spring or fall) to affect any measured parameter. Cover crops appear to increase soil N and C stocks through the addition of organic matter and influence P distribution throughout the soil profile; however, the lack of an interaction with time indicates that cover crop effects dissipate quickly in the production systems of the humid subtropical midsouthern United States.