Higher yields and intensive cropping make high demands for nutrients from soil, which leads to depletion of soil nutrient reserve. K removal by the intensive cropping is disproportionately higher than the amount of K added through fertilizer as evident from the results of Long term fertilizer experiments in Tamil Nadu and elsewhere in India. The nutrients exported out of the farm in crop produces must be necessarily replenished to sustain soil fertility and therefore the production system for which balanced fertilizer application is the prerequisite and there is growing need for site specific balanced fertilizer recommendations according to the crop type, yield level and soil conditions. Balanced fertilizer schedule were developed for rice, maize, cassava, peanut, potato, tobacco etc. by the applications of mathematical models and decision support systems. The soil salinity or sodicity hinders the crop growth and yield. The industrial by-product Ferrogypsum from the effluent treatment plant of titanium industry was evaluated as a substitute for gypsum to alleviate sodicity besides its effect on increasing crop yields in paddy and groundnut.