Effects of Biogas Digestion of Slurry, Cover Crops and Crop Residues on Nitrogen Cycles and Crop Rotation Productivity of a Mixed Organic Farming System

Summary

Manures and crop residues can be utilised for digestion, without any significant losses of nutrients. This paper presents the results of field trials about the effects of biogas digestion in a mixed organic cropping systems on nutrient cycling and yield of a whole crop rotation. Digestion of slurry affected yields and N uptake only after soil incorporation. The inclusion of crop residues for digestion increased the amounts of “mobile” manure. N uptake and yield of non-leguminous main crops increased about 10%, due to a more adapted allocation of nutrients within the whole cropping system by reallocation of N towards the crops with higher N needs. Additionally, removing the cover crops in autumn and their digestion increased the fertilizing efficiency of N, lowering the risk of leaching losses.