Amendements organiques et maraîchage biologique sous abri : 6 ans d'expérimentation

Six-year study at INRA Alenya examines compost applications in greenhouse vegetable systems under plastic cover. High compost rates (13–24 t/ha/year) of green waste or commercial compost (coffee bales, sheep manure) slightly improved soil biological activity and nitrogen nutrition, particularly with VG13, but had minimal impact on soil physico-chemical properties or crop yields. Standard doses (4 t/ha/year) showed negligible effects. Low initial soil organic matter (50 t/ha) and residual nitrogen from prior conventional fertilisation masked input benefits. Solarisation increased nitrate levels, aiding lettuce, but summer tomatoes faced nitrogen deficits without supplementation. Results suggest that endogenous mineralisation and residual nitrogen stocks sustain crop nutrition during organic transition, highlighting the need for tailored nitrogen management and long-term monitoring in intensive greenhouse systems.