The Properties of Rice Stubble Compost and Its Effects on Okra Yield (Abelmoschus Esculentus L.), Nutrient Activation Coefficient, And Organic Carbon Fractions in Soil

Rice stubble is an important agricultural waste product in Thailand. Using the rice stubble to make a compost is an effective way to dispose of this material as a lot of rice stubble is needed to make compost. The aim of this study was to investigate the relationship between rice stubble and other materials such as rock phosphate and cow dung on the properties of the compost and its effects on okra yield and soil properties after harvest. The results showed that the different proportions of rice stubble, rock phosphate and cow dung had an effect on the compost properties, with the compost formulation CP4 (40% rice stubble: 30% rock phosphate: 30% cow dung) showing the best properties. Varying the components of the compost formulations had no effect on pod yield and N and P uptake but these properties were significantly different when compared to the control. The application of compost helped to improve soil properties after planting. In particular, the compost formulation CP4 resulted in a higher available P content (97.1 mg/kg) in the soil than the other treatments. The application of compost increased the nutrient activation coefficient, particularly the phosphorus activation coefficient (PAC). It also increased the active carbon pool, especially the very labile carbon, which can easily release nutrients to the plants. The results suggested that reducing rice stubble and increasing rock phosphate and cow dung could improve compost properties. In addition, the use of rice stubble compost enhanced soil fertility, PAC, and active carbon content in the soil.