Effect of Soil Aggregate Size and Organic Matter on Tomato Early Growth, Yield and Root and Soil Physicochemical Properties

This study investigates the independent and combined effects of soil aggregate size (A1: <2 mm, A2: 2–4 mm, A3: >4–8 mm) and organic matter (OM) on tomato growth and soil properties. A pot experiment with a completely randomized design evaluated six treatments (a1b0, a1b1, a2b0, a2b1, a3b0, 3b1), where B1 represents the addition of 10% cow manure compost by soil dry weight, while B0 indicates no compost addition. Results demonstrated that OM alone significantly enhanced early root growth, plant height (79 cm vs. 44.6 cm without OM), leaf count (161 vs. 47 leaves), and fruit yield, which increased by a factor of 39 compared to non-OM treatments. larger aggregates (>4–8 mm) significantly reduced soil bulk density (0.84 vs. 1.22 g cm⁻³ in A1) and increased available phosphorus by 30–40%. Interactions between OM and aggregate size significantly influenced tomato yield, total soil nitrogen, and hydraulic conductivity. The combination of large aggregates and OM (a3b1) boosted total nitrogen by 200–300% and fruit yield by 39 times compared to a1b0. While OM primarily enhanced root vigor and nutrient availability, aggregate size modulated phosphorus accessibility and physical soil structure. These findings underscore OM’s dominant role in improving productivity and soil fertility, while aggregate size plays a crucial role in optimizing soil structure. Strategic integration of OM and aggregate management can enhance sustainable agricultural practices by balancing soil health and crop performance.