The Effects of Biochar from Rice Husk and Chromolaena odorata on the Soil Properties and Tomato Growth in Cambodia

Abstract

Supplies of soil amendments and fertilizers are major constraints to increasing crop productivity in rural Cambodia. In order to test and compare potential soil amendments, we examined the effects of biochar from rice (Oryza sativa L.) husk and Siam weed (Chromolaena odorata), with and without fertilizer on plant growth and soil properties. Tomato (Solanum lycopersicum L.) was grown on loamy sand (clay-silt-sand = 9-10-81), with a pH of 7.7, and exposed to the following seven treatments: no input (control), rice husk biochar (RB), rice husk biochar + compost (RBcom), rice husk biochar + NPK (15:15:15) fertilizer (RBchem), C. odorata biochar (CB), C. odorata biochar + compost (CBcom), and C. odorata biochar + NPK (CBchem). The results showed that only CBchem provided significantly greater fresh root weight (+58%) and total fresh biomass (+166%) than control. RB, RBchem, and RBcom did not increase all the parameters on plant growth and soil properties. The soil pH of CB (7.8), CBcom (7.9), and CBchem (7.7) were significantly enhanced as compared to control (7.3). Compared to CBchem, CBcom caused greater increases in soil pH, EC, available P, available N, exchangeable Ca, and exchangeable K, although those increases were not statistically significant. Hence, C. odorata biochar was considered as a nutrient-rich amendment that had a high amount of N, P, Ca, Mg, and K after the charring process, and contributed to improve plant growth.