Effect of surface-applied compost on soil properties

The positive influence of surface compost application without incorporation on soil physical properties is known but remains underexplored. This study evaluated the effects of surface-applied stable and mature compost on basic soil physical and chemical properties, including saturated hydraulic conductivity, aggregate stability, and penetration resistance. Conducted as a semi-operational field experiment in two Czech agricultural sites (A: Blatnice at Jaroměřice and B: Jevíčko; Cambisols with loam and silty clay loam textures, respectively), the plots were treated with compost (SCA) at rates of 4 × 30 t/ha (A) and 1 × 200 t/ha (B) or left untreated as controls (CON). The crops were wheat (A), maize (A, B) and intercrops. Surface compost application began in 2022, and soil sampling and field measurements were conducted during the 2023 and 2024 growing seasons. Results showed significant positive changes (P < 0.05 or lower) in SCA plots compared to CON. Soil organic matter content increased by 27.8% at locality A and by 58.1% at locality B, while saturated water content increased by 5.3% (A) and 11.0% (B) in the latter season. Similarly, pH and electrical conductivity showed increases. Water-stable aggregate ratios increased by 6% to 30% at both localities. Dry bulk density decreased by 10.5% (A) and 15.7% (B). Improvements in saturated hydraulic conductivity (by 28.6%) and penetration resistance were observed only at locality B. These findings show the potential of surface-applied stable and mature compost to enhance soil properties effectively.