Auswirkungen der Grüngutapplikation auf den Stickstoffhaushalt in landwirtschaftlich genutzten Böden

Field experiments on loamy (with winter wheat) and sandy soils (with winter rye) were conducted to study mineral nitrogen dynamics after the application of different amounts of shredded shrubs in combination with liquid manure. In the spring, shortly after the application, the mineral nitrogen decreased on sandy soils moderately because of the shredded shrubs. This can be attributed to higher N immobilisation. The same effect was observed in autumn on both fields. In this season, the decline of mineral nitrogen is advantageous because it leads to a subsidence of nitrogen leaching. Due to the re-mobilisation of the fixed nitrogen and gradual decomposition of the shredded shrubs, the mineral nitrogen increased slightly in the mulched fields in the second year. A higher layer of mulch and/or the combination with the liquid manure tended to increase the effect of the shredded shrubs. The variability of the soils played an important role in the mulch mineralisation. The shredded shrubs collected in Hannover County cannot be classified as organic fertiliser because of a lack of soluble nutrients. Only soluble potassium exhibited a higher amount in this organic material.