Biochar is a solid substance made by carbonizing biomass. Biochar can be added to the soil and used as a soil conditioner to improve the function of the soil. This study was conducted to investigate the effect of rice hullderived biochar application on the growth, yield and soil physico-chemical properties of the watermelon cultivated under greenhouse. Rice hull-derived biochar was tested with 0 (no treatment), 1,000, 2,000, and 4,000 kg per ha levels. Among the growth characteristics of watermelon harvest season, rice hull-derived biochar application thickened stem diameter and increased fresh weight. The weight of watermelon was the heaviest in 2,000 kg ha -1 rice hull-derived biochar application, and the sugar content of watermelon was 0.3 -0.4°Brix higher than that of control 11.5°Brix. The watermelon yield was the highest at 52,990 kg ha -1 in 2,000 kg ha -1 rice hull-derived biochar application, which was higher than that of control. Changes in soil chemical properties of rice hull-derived biochar application were increased with pH, exchangeable K, Ca and Mg, but available phosphate acid was decreased. The bulk density decreased and the porosity increased with the rice hull-derived biochar application. These results suggest that the rice hull-derived biochar application to the watermelon cultivation area could improve the productivity of watermelon by improving the physico-chemical properties of watermelon cultivation area.

This study was conducted to examine the effect of mixed organic fertilizer (MOF) application on the growth, yield, soil chemistry change, and bio-active component of Saururus chinensis Baill in paddy cultivation under organic cultivation practice. Saururus chinensis Baill were cultivated with five levels of MOF application including 50% treatment based on the nitrogen content of the soil test fertilization recommendation. The plant length increased with the increased MOF application, and the fresh weight of the above-ground part was the highest in the 100% MOF treatment and the rhizome was the highest in the 125% MOF treatment. Among soil chemistry, pH was lowered, and available phosphorus increased as the MOF application rate increased. Phosphorus and potassium contents in the leaves increased with the MOF rate. The bio-active component (quercetin) in the leaves also increased proportionally with the MOF rate, In the rhizome, the content of quercitrin showed an opposite pattern to the above-ground part. The MOF for obtaining the highest yield of Saururus chinensis Baill were 100% MOF for the above-ground part and 150% MOF for the rhizome.