Model-based investigations into long-term compost application effects on nitrate leaching at different agricultural sites
Organic waste materials may beneficially be used for fertilisation as well as for soil improvement on agricultural sites after composting and subsequent application. If compost is continuously applied at an annual scale of app. 10 Mg dry matter/ha, the content of organic matter in the soil will increase in the long-term, as shown in a field trial in Neu-Eichenberg, conducted 1985-97 by Univ. of Kassel and PlanCoTec. Nutrients, especially nitrogen, can increasingly be released from organic matter into water-soluble and mobile compounds (e.g. nitrate) when humus contents are high. If not taken up by plant roots, nitrate is quickly translocated in humid climates and in sandy soils and may leach into the ground water. Therefore, compost application has to be managed according to site, crop rotation and cultivation in a way which allows beneficial use for plant production and, with good agricultural practice, allowing only low, unavoidable ground water pollution.
Aim of this study was therefore the estimation of the long-term impacts of compost application with regard to nitrate leaching with the help of a simulation model. The results serve as a base for conclusions on the optimum compost amendment in agriculture. This study was financially supported by the German Federal Ministry for Education, Research and Technology (BMBF).