US EPA

6974049 

Journal Article 

Calculation of net nitrogen mineralization from the decomposable soil organic matter pool 

Ruhlmann, J; , 

1999 

INTERNATIONAL SOCIETY HORTICULTURAL SCIENCE 

LEUVEN 1 

167-173 

WOS:000085603500023 

The calculation of Net Nitrogen Mineralization (NNM) presented in this paper was based on the assumption that soil organic matter carbon may be divided into a stable, texture dependent pool (C-stab) and a labile, decomposable pool (C-dec) Because the C-stab pool is biologically inert due to its interaction with fine-grained mineral soil particles, only the C-dec pool reflects man made changes in the soil organic matter content. Consequently, to estimate the rate constant of soil organic matter carbon, the CO2-C production of soils was related to the corresponding amounts of C-dec Because this rate constant k(dec) was derived from incubation experiments, the influence of actual decomposition conditions in the field was calculated according to the concept of "Effective Mineralization Time" (EMT). Setting the C/N ratio of C-dec = 10, the NNM from the C-dec pool was calculated according to the Equation: NNM = 0.1 * C-dec * k(dec) * EMT. To evaluate the calculation method of NNM, the nitrogen uptake of plants was related to nitrogen supply. It was estimated that the mean recovery of N by different vegetable crops grown on plots without mineral nitrogen fertilizer was about 70% of the total nitrogen supply (including the NNM and the N-min values at the start and the end of the cultivation period). 

Burns, IG; Bending, GD; Mulhollaand, B; 

90-6605-802-1 

International Workshop on Ecological Aspects of Vegetable Fertilisation in Integrated Crop Production in the Field 

WELLESBOURNE HASTINGS, ENGLAND