Decomposition and nitrogen release of cover crops in reduced‐ and no‐tillage systems

Abstract

AbstractCover crops (CC) are versatile and have multifunctional benefits in crop rotations. An understanding of the effect of tillage systems on cover crop (CC) residue decomposition and nitrogen (N) release is essential in cash crop production planning. We investigated the decomposition rate and N release from cereal rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth.) CC residue in no‐tillage (NT) and reduced‐tillage (RT) systems under corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotations. Litterbags were placed in the soil in RT and on soil surface in NT after CC termination in April and collected weekly for 10 wk to measure residue and N retained. Tillage systems did not affect the decomposition rate constant (k) and accumulated N release for both CC. Hairy vetch residue decomposed faster (k = 0.3494) than cereal rye (k = 0.1955) and released a greater amount of N in the soil (hairy vetch vs. cereal rye = 60 vs. 28 kg ha−1), attributable to greater N concentration and narrow C/N ratio compared to cereal rye in 2017 and 2018. Hairy vetch rapidly released N in the soil within 2 wk of termination. Both cover crops had greater decomposition rate constant and accelerated mass loss in 2018 than in 2017, possibly due higher spring temperatures in 2018 than 2017. Hairy vetch CC after terminating greatly enhance N availability in the soil, therefore, alternate management practices like planting green for grain crop following hairy vetch CC might be needed to capture released N.