Removing vegetable crop residues for composting and ensilaging: effects on N, P and organic matter

The crop residues of vegetables may have a high nitrogen (N) content. These residues often remain on the field after harvest and may lead to nitrogen leaching. Besides having an adverse effect on water quality, such losses of N do not fit within sustainable agriculture practices, where the optimal maintenance and use of nutrients is crucial. However, crop residues are important for phosphorus (P) and organic matter cycling. This study investigates the extent of preventing N loss by removing crop residues, followed by composting or ensilaging. Removal of organic matter and P is assessed as well. Crop residues of cabbage were harvested with common available machinery. For composting, wood chips and bark were mixed with crop residues of corn maize, white cabbage or leek for a good compost composition. Crop residues of white cabbage, celery, cauliflower or leek were mixed in a 50/50 volume ratio with corn maize stover. Ensilage conserves the nutrients for reuse on the field after the winter or for other applications. Feedstock materials, composts and silage were analysed for chemical characterisation. The effects of compost and ensilaging on the N-mineralisation in the soil will be evaluated using an incubation experiment. Also the economic and technical feasibility will be assessed based on the availability of adequate tools, labour and transport costs for the removal of crops.