Rice Husk Biochar for Rice Based Cropping System in Acid Soil 1. The Characteristics of Rice Husk Biochar and Its Influence on the Properties of Acid Sulfate Soils and Rice Growth in West Kalimantan, Indonesia

The experiments were carried out to study the characteristics of biochar made from rice husk and its potential as a soilamendment in acid soils. Biochar was produced by pyrolysis; after which it was applied as a soil amendment. The soilwas incubated for 30 days, and then it was planted with rice. For comparison, soil was applied with: rice straw, ricehusk, rice husk ash, Chromolaena odorata biomass, and no soil amendment. The characteristics of biochar were: watercontent 4.96%, pH 8.70, C 18.72%, P 0.12%, CEC 17.57cmol kg-1, K 0.20%, Ca 0.41%, Mg 0.62%, and Na 1.40%.Application of biochar decreased soil bulk density, soil strength, exchangeable Al, and soluble Fe and increased porosity, available soil water content, C-organic, soil pH, available P, CEC, exchangeable K, and Ca. Out of these improvements, only soil carbon, phosphorus, exchangeable Al, soluble Fe, and soil strength significantly influenced rice biomass