Agronomic, Biochemical and Metabolic Responses of Tomato to Vermicompost and Mineral Fertilization in Loam and Clay Soils
The intensive use of mineral fertilizers in horticultural systems has improved crop productivity but also increased concerns regarding soil degradation and environmental sustainability. In this context, vermicompost derived from buffalo manure may represent a sustainable alternative for nutrient management and organic waste valorization. This study evaluated the effects of four fertilization strategies on tomato (Solanum lycopersicum L.) grown in loam and clay soils: unfertilized control, mineral fertilization, vermicompost applied at an equivalent nitrogen rate, and the residual effect of vermicompost from a previous cauliflower crop. Agronomic performance, fruit quality, carbon and nitrogen metabolism, and antioxidant-related traits were assessed. Mineral fertilization produced the highest marketable yield, reaching 9.68 and 7.69 kg m−2 in loam and clay soils, respectively, mainly through increased fruit number. Direct vermicompost application maintained substantial productivity, with yields of 7.55 and 5.18 kg m−2 in the two soils. The fertilization strategies also induced distinct changes in fruit composition. Mineral fertilization increased total free amino acids to approximately 160 mg g−1 DW, mainly through the accumulation of glutamine, glutamate, asparagine and γ-aminobutyric acid, but was associated with lower soluble solids and antioxidant activity. Vermicompost promoted the highest lycopene concentration, approximately 2.1 mg g−1 DW, in clay soil and maintained intermediate antioxidant activity and amino acid concentrations. Soil texture also influenced carbohydrate partitioning, with greater fructose accumulation in clay soil and greater starch accumulation in loam soil. The residual vermicompost treatment alone did not adequately sustain tomato productivity or metabolic activity, particularly in clay soil. Overall, vermicompost partially replaced mineral fertilization while maintaining satisfactory yield and modulating fruit metabolic quality, although its effectiveness depended strongly on soil texture.