Nitrogen management in organic horticultural rotation

A field crop rotation with a cover crop of hairy vetch (Vicia sativa, L.) and rye (Secale cereale, L.)followed by potato (Solanum tuberosum L.) and lettuce (Lactuca sativa, L.)was set up with the aim of improving nitrogen (N) management for organic agriculture. N mineralization was determined by a field incubation in response to green manure and increasing rates of compost (20 and 40 t/ha) and organic commercial ferlizer (1 and 2 t/ha). N mineralization in compost took place during all crop rotation, but most of the organic fertlizer was mineralized during the first days after soil application. Consequently, N availability and potato crop yield was increased with 2 t/ha of organic fertilizer compared to 20 t/ha of compost, whereas lettuce yield increased with compost application in comparison to organic fertilizer.