4665: The turnover of soil organic matter on different farm types

Petersen, B.M. and Berntsen, J. (2003) The turnover of soil organic matter on different farm types. DARCOFenews(3). Online at <http://www.darcof.dk/enews/sep03/orgmat.html>^*

Summary

One of the prime factors determining soil fertility is the content of soil organic matter. A huge amount of nitrogen (N) is bound in organic matter, and the yearly mineralisation of N in the field is only a small fraction of the total organic nitrogen.The release and incorporation of organic N is of special relevance for organic farms, where the crop supply mainly depends on N mineralised from organic matter.In order to study the long-term balance between build-up and degradation of organic matter, a simple simulation model was made, calibrated on the basis of long-term data from Sweden, U.K. and Denmark. Briefly, it is a 3-pool model (Figure 1) employing first-order kinetics, which is implemented in C-TOOL. The long-term build up or breakdown of organic N is assumed to follow carbon in the ratio 1:10.

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