Effects of vermicompost application rates and irrigation regimes on tomato yield, nutrient uptake and soil properties under greenhouse conditions

Tomato (Solanum lycopersicum L.) is a widely cultivated horticultural crop that responds sensitively to both nutrient availability and water management. The use of vermicompost as an organic fertilizer offers potential to improve plant productivity and soil health, especially under conditions of limited irrigation. This greenhouse study aimed to investigate the effects of different vermicompost application rates and irrigation levels on tomato yield, leaf nutrient uptake, and post-harvest soil properties. The experiment was conducted using a clay soil with low fertility characteristics (organic matter 1.15%, total N 0.06%, available P 5.26 mg/kg) and vermicompost rich in nutrients (total N 1.52%, total P 0.46%, total K 2.85%). Treatments consisted of four vermicompost rates (0, 0.25, 0.5, and 1.0 t/da) combined with three irrigation levels (100%, 75%, and 50% of field capacity) in a completely randomized design with three replications. Tomato plants were grown under controlled greenhouse conditions, and yield per plant, leaf nutrient contents (N, P, K, Ca, Mg), post-harvest soil nutrient status, and biological properties (microbial biomass carbon, soil respiration, enzyme activities) were evaluated. Results indicated that both vermicompost and irrigation level significantly affected tomato yield, which increased from 4.90 kg/plant (control, 50% FC) to 8.00 kg/plant (1.0 t/da, 100% FC). Leaf nutrient concentrations and soil available N, P, K, Ca, and Mg were significantly improved with higher vermicompost doses. Soil microbial biomass and enzymatic activities also responded positively to vermicompost, while water stress had suppressive effects. The interaction between vermicompost and irrigation was generally not significant, suggesting additive but independent effects. In conclusion, the application of vermicompost at 1.0 t/da improved tomato yield, nutrient uptake, and soil quality indicators, even under moderate water stress. This study supports the integration of organic amendments and optimized irrigation as a sustainable strategy for tomato production in protected cultivation systems.