Diagnosis of Nutrients Constraint of Increasing Peanut Yield on Alfisol

Diagnosis and characterization of land is one important step to distinguish: a constraint of increasing yield, type of management is being required, and yield potential figure. The research was done and concentrated in Ngadirojo subdistrict, Wonogiri, Central Java province. The methode of survey is soil sampling and taking soil sample in top soil in 0-20 cm depth. Soil samples were taken up from 11 villages, each villages was taken randomly at two sites. Analysis of soil sample consisted of status P, K, Ca, Mg, S, pH, C-organic and micro nutrients Fe and Zn. A part from soil sampling, it was done yield cut survey for peanut at the famers field. The agronomic data of yield cut survey consisted of yield and component of yield. The result of diagnosis and chracterization indicated that (1) all the villages area of Ngadirojo sub district have low nitrogen fertility, (2) The phosphorus fertility in Ngadirojo is vary, there are six location (27%) having low P fertility status, eleven location (50%) having medium P fertility status, and five location (23%) having high P fertility status, (3) Potassium fertility status in Ngadirojo indicated that 45% area have low K fertility and high status for the rest, (4). The sulfur fertility is vary from low to high, (5). The Ca, Mg, and micronutrients are high at all location of Ngadirojo sub distrist, (6). There is a big challenge to minimize yield gap of peanut at Ngadirojo sub district, and (7) At farmers level, the hole planting techique by hue ("sistem koak") produced peanut yield higher than drill ("tugal”) technique. It can be concluded that the N, P, K, and S are considered as the constraint nutrients for increasing peanut production in Alfisol of some area of Ngadirojo sub-district. All area in Ngadirojo sub-district having a good fertility for the secondary nutrient such as Mg and Ca, and the micronutrients such as Fe, Cu, Mn. There is an opportunity to increase peanut yield by improving farmer’s practice using innovative technology, especially by improving nutrients and crop management system.