IN-SITU STUDIES OF SOIL MINERAL N FLUXES - SOME COMMENTS ON THE APPLICABILITY OF THE SEQUENTIAL SOIL CORING METHOD IN ARABLE SOILS

Is the sequential in situ incubation of undisturbed soil cores, develo ped for forest stands applicable to arable soils? The incubation of co vered and uncovered soil cores allows the estimation of net nitrogen m ineralization (NNM), plant nitrogen uptake (N-uptake) and potential le aching losses (N-trans). The amounts and temporal dynamics of these N fluxes were determined at four arable soils in a two-year study. Resul ts suggest that: (i) the method can not be recommended for the estimat ion of N uptake and leaching losses, but (ii) it is suitable for the e stimation of NNM; (iii) incubations should preferably be started when soil is moist; (iv) the length of incubation periods should be reduced (< 4 weeks); (v) dynamics of NNM is mainly determined by temperature and moisture conditions if there is no interference by agricultural ma nagement. Inputs of straw, manure, slurry or green manure strongly inf luence the amount and the dynamics of NNM.