Nitrogen Dynamics in Living Mulch and Annual Cover Crop Corn Production Systems

Abstract

White clover (living mulch), crimson clover, and rye cover crops were used for corn production. Plant‐available N was determined for each cover crop system to estimate N release. Soil N forms and the timing of N availability varied among the cover crops. Internal N use was similar but partial factor productivity and partial nutrient balance was greatest in the living mulch cover crop. Successful living mulch (LM) systems may be capable of meeting the N requirements of corn (Zea mays L.) despite competition during corn development. This study compared corn N dynamics in a perennial white clover (Trifolium pratense L.) LM system and annual cereal rye (Secale cereale L.) (CR) and crimson clover (Trifolium incarnatum L.) (CC) systems. Corn in the LM, CC, and CR cover crop systems received 56, 168, and 280 kg N ha−1, respectively. The mean total N provided from the cover crops was 145, 105, and 25 kg ha−1 in the LM, CC, and CR cover crop systems, respectively. Water uptake by the LM reduced soil water content, soil N availability, N uptake, and plant‐available N (PAN) compared with the CC and CR cover crop systems. Average grain yield was 10.4, 13.3, and 13.0 Mg ha−1 for the LM, CC, and CR cover crop systems, respectively. Nitrogen internal utilization efficiency was not different among systems, but fertilizer N partial nutrient balance and partial factor productivity was greatest for LM and least for CR. Overall, the LM system had lower soil N availability, grain yield, and PAN, but it supplied a significant amount of legume N to corn and minimized the need for mineral N. We concluded that success of the LM system is dependent on N mineralization of the white clover residue and that yearly weather variation significantly affects mineralization of cover crop residues and PAN.