Effects of Mineral and Organic Fertilizations on Yield of Hot Pepper and Changes in Chemical Properties of Upland Soil

This study was conducted to investigate the effects of mineral and organic fertilizer application on pepper (Capsicum annuum) yield and soil chemical properties for 14 years from 1994 to 2007. For the experiment, experimental plots were established on a sandy loam soil with six treatments, which consisted of no fertilization (NPK), N+P+K standard fertilization (NPK), N+P+K+compost (NPKC), P+K+compost (PKC), N+P+compost (NPC), and N+K+compost (NKC). During the 14-yr experimental period, organic matter contents in soil increased continuously at the rate of 1.11-1.17 g.kg.yr in the treatments with compost applications and 0.51-0.55 g.kg.yr in treatment with no compost application. The soil available phosphate in NPK treatment increased at the rate of 3.6 mg.kg.yr, which was insignificant compared to those in compost applied treatments such as 16.1 mg.kg.yr in NKC and 45.0 mg.kg.yr in NPKC. As cultivation periods for pepper was extended, exchangeable potassium concentrations in soil tended to decline continuously. But, exchangeable potassium content in soil showed no further decline at the level of 0.22 cmol.kg in NPK and 0.50-0.71 cmol.kg in NPK treatment. Fruit yield and the amount of nutrient absorbed by pepper increased in the following order: NPK NPC