Sulaeman, D. Nursyamsi, L.R. Widowati, Husnain, M. Sarwani
This paper discusses the Phosphorus and Potassium Decision Support System (PKDSS) developed by ICALRD and its role in bridging soil database and fertilizer application. This system is a fertilizer recommendation model, as well as a computer program, used as a tool in determining fertilizer requirement for a given crop based on soil testing. In Indonesia, balanced fertilizer application approach is adopted to increase crop production while reducing negative impact on environment. This approach requires a better insight on soil characteristics and behavior. The soil nutrient status determines fertilizer recommendation for a given crop. The PKDSS recommends fertilizer rate after correcting the standard rate by its correction factor. The correction factor indicates the effect of selected soil properties on soil nutrient dynamics. N-fertilizer is corrected by soil texture class and soil organic carbon content. P-fertilizer is corrected by soil texture class, soil pH, soil organic carbon content, and P-retention. K-fertilizer is corrected by soil texture class, soil organic carbon content, and cation exchange capacity of clay. PKDSS needs 14 soil properties as input, divided into two layers: first layer to select the standard recommendation and second layer to determine the correction factor. These soil properties can be provided by soil data stored in the soil database. These legacy data can be used to create quantitative soil property maps by using digital soil mapping techniques. These maps are inputted to PKDSS to come up with fertilizer recommendation area (FRA) for a given crop. The FRA assists the local government in planning fertilizer stock and distribution in each agricultural service. PKDSS plays an important role in bridging soil database and fertilizer application.
Keywords: PKDSS, digital soil mapping, legacy soil data, fertilizer recommendation area.