Nitrogen Release Dynamics and Decomposition of Buried and Surface Cover Crop Residues

Abstract

Integrating cover crops into farming systems may contribute to meeting N demands of succeeding crops and therefore decrease fertilization and environmental concerns. To study the trend of released N in buried (BR) and surface residues (SR) of three different cover crops a 2‐yr field experiment was conducted in a randomized complete block design on a fine sandy loam. Forage radish ( Raphanus sativus L.) and winter pea ( Pisum sativum subsp. arvense L.) decomposition rate and N release trend were compared with cereal rye ( Secale cereale L.), as the conventionally grown cover crop in Massachusetts, to evaluate if forage radish or winter pea would provide more N for early planted crops in the spring than cereal rye. Forage radish produced the highest dry matter yield (3.46 Mg ha −1 ) followed by winter pea (3.1 Mg ha −1 ) and cereal rye (2.42 Mg ha −1 ). All of the cover crops had a faster residue decomposition and release of N when buried in the soil. Through the decomposition period, forage radish and winter pea lost their initial biomass and N concentration faster than cereal rye in both BR and SR due to higher C/N ratio and lignin concentration in rye. Our results showed a greater potential of forage radish or winter pea for a synchronous N release relative to crop N demands early in the spring than with cereal rye. Core Ideas Forage radish has great potential for synchronous N release with cash crop N demands early in the spring. A high N yielding winterkilled cover crop is preferred over rye if early planting of cash crop is target. Rye may not provide the succeeding crop with sufficient N when terminated early.