Estimation of nitrogen release from decomposing Zoysia japonica litter using its relationship to mass loss

Abstract To estimate nitrogen release through the decomposition of Zoysia japonica litter, we conducted 2‐year litter‐bag measurements for dry matter loss and nitrogen dynamics of decomposing litter on the soil surface of a Z. japonica pasture in central Japan, and modeled the nitrogen release from the litter. The litter mass decreased to approximately 50% in the first year with a steep decline in summer and a gradual decline in winter. The nitrogen concentration of the litter increased with incubation time, while the amount of nitrogen in the litter changed minimally for more than one year and then gradually declined to approximately 60% of the initial amount at the end of the incubation. The model for estimating nitrogen release from the litter was established as a cubic relationship to the litter mass, because nitrogen concentration of the litter was well expressed as a quadratic function of the litter mass loss. The litter mass loss was estimated using a negative exponential equation in which the decomposition rate increased linearly with air temperature. The model can be used as a submodel of an integrated model for simulating nitrogen cycling in Z. japonica pastures in an area with sufficient rainfall.