A nutrient decision support system for rainfed cashew

Abstract

In cashew, the recommended dose of fertilizers/manure per plant is effectively applicable up to 80-100 percent canopy coverage depending upon the age of the plant, plant density, soil fertility level and varieties used. After 6-8 years, a cut down of recommended doses of fertilizers or manures per plant is necessary depending on the nutrient build up in cashew garden due to the addition of nutrients from the increased cashew biomass deposit. For the judicious use of fertilizers and manures, prior soil testing is required for getting the nutrient status in the soil from time to time. A nutrient decision support system (NDSS) was developed for cashew using Visual Basic package for determining the site specific fertilizer and or manure requirement. The optimal fertilizer and manure requirement is based on the nutrient budgeting and nutrient balance approach and it depends on plant density, age of the plant, canopy biomass fallout, canopy wash nutrients, optimal yield of cashew, initial soil NPK, removal of NPK by plants and post soil NPK. The developed decision support system which was validated using field data is having the flexibility of giving the optimal quantity of inorganic fertilizers and or organic manures as selected by the user. The regression analysis of the measured optimal values against the predicted values of the inorganic fertilizers and organic manures showed a reasonable fit between two data sets (R² = 0.95 for inorganic fertilizers and R² = 0.94 for organic manures). The quantity of nutrient application to rainfed cashew can substantially be reduced using the estimated quantity obtained from NDSS.