Effects of combined compost on soil pore distribution and available water capacity in tropical coffee plantations
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Brawijaya University
Malang 65145, East Java, Indonesia
Corresponding author
Sugeng Prijono
Brawijaya University
Malang 65145, East Java, Indonesia
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ABSTRACT
Physical soil degradation in smallholder coffee plantations threatens water availability and increases drought vulnerability. This study examines the effect of single and combined compost derived from Saccharum officinarum leaves, Coffea canephora pulp, and Gliricidia sepium leaves on soil pore distribution and available water capacity (AWC) in Typic Humudepts, Sumbermanjing Wetan, Malang. The experiment was arranged in a Randomized Block Design (RBD), comprising seven treatment combinations each replicated three times. Compost was applied at 40 cm depth at 10 kg plant⁻¹ year⁻¹, with soil samples collected at 0–49 cm and 49–60 cm one year after application. Compost type significantly affected total porosity and AWC at both depths. Treatment P4 (50% Coffea canephora pulp + 25% Saccharum leaves + 25% Gliricidia leaves) produced the highest porosity (0.77 cm³ cm⁻³) and AWC (0.30 cm³ cm⁻³) in the topsoil, increasing macroporosity by 6%, mesoporosity by 26%, and decreasing microporosity by 24% relative to the control. AWC was primarily governed by total porosity. These findings indicate that blending compost optimizes soil pore distribution and AWC, providing a practical and acessible approach to strengthen drought resilience in smallholder coffee systems.