Enhancing Soil Physical Quality with Compost Amendments: Effects of Particle Size and Additives

This research investigates the impact of compost particle size, compost additives, and application rate on the physical properties of loamy sand soil, particularly focusing on water retention characteristics. Compost, enriched with additives like zeolite, biochar, and diatomite, was applied to soil in different rates: 1%, 2%, and 4%. Compost particles were divided into three particle size classes: 0–500 µm, 500–1000 µm, and 1000–2000 µm. The study revealed significant effects of compost on soil physical quality, including bulk density, porosity, and water retention. Zeolite-enriched compost showed the most pronounced improvements in soil water retention by modifying pore diameter. However, the effectiveness of compost additives varied depending on the type and rate of application. Compost with zeolite resulted in a decrease in the volume of large soil pores with diameters of 50–500 µm and above 500 µm. This resulted in higher water retention related to mesopores. Larger compost particles (1.0–2.0 mm) exhibited superior effects on soil physical quality compared to smaller particles (<1.0 mm), although finer particles (0.5–1.0 mm) were associated with higher water repellency. Compost with diatomite resulted in higher water repellency than other compost types. The findings underscore the importance of considering compost particle size, component type, and application rate to optimize soil hydraulic characteristics, particularly in agricultural practices where water management is crucial.