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Calculation of N Mineralization from Six Green Manure Legumes under Field Conditions from Autumn to Spring

1991; Taylor & Francis; Volume: 41; Issue: 3 Linguagem: Inglês

10.1080/00015129109439907

0001-5121

Holger Kirchmann, Håkan Marstorp,

Agronomic Practices and Intercropping Systems

Abstract Mean soil temperature values and optimal moisture conditions were incorporated into a kinetic first-order model to describe net nitrogen mineralization from above-ground legume material under field conditions. Calculations showed that red clover, persian clover and egyptian clover would mineralize 1 to 2 kg N ton-1 above-ground legume dry matter from autumn to early spring, whereas white clover, black medic and subterranean clover would mineralize between 6 and 13 kg N ton-1 of dry matter during the same time period. Late ploughing (December 1) compared to early ploughing (October 15) had a substantial effect on the initial amounts of N released but differences decreased and were small in May. Assuming an above-ground legume biomass of 3 tonnes of dry matter, up to 40 kg N per hectare can be mineralized from autumn to early spring depending on the legume species. The species had a larger influence on the mineralized amounts of N than the location and the time of ploughing. Key words: Trifolium pratense L.T. repens L.T. resupinatum L.T. alexandrinum L.T. subterraneum L.Medicago lupulina L.