Optimized N-mineralization parameters of loess soils from incubation experiments

Abstract

Nitrogen mineralization from long term incubation experiments with dried loess soils from southern Lower Saxony has been split by an optimization procedure into three contributing fractions: one from the resistant organic material (index rpm), another from decomposable plant residues (index dpm), and a third one from autolyzing microbial biomass (index bom). The nitrogen contents at the end of February averages 650 kg nitrogen per hectare and the 30 cm arable layer for the rpm, 30 to 50 kg N/ha for the dpm and about 65 kg N/ha for microbial biomass. The corresponding mean reaction coefficients at 35°C are .0058, .16 and about .35 per day, respectively. A rough approximation of the temperature dependence of the reaction coefficients has also been estimated.