A field experiment was conducted during rabi 2006 to evaluate soil test based fertilizer prescription equations for targeted yield of Indian mustard (Brassica juncea L.) on alfisol, A.P. based on the targeted yield concept. In targeted yield approach for calibrating and formulating fertilizer recommendations, the basic data required are (i) nutrient requirement in kg q –1 of produce, grain or other economic produce (ii) the per cent contribution from the soil available nutrients (% CS), (iii) the per cent contribution from the applied fertilizer nutrients (% CF) and (iv) The above basic data are transformed into simple workable adjustment equations. The basic data and targeted yield equations have been developed for mustard in Alfisols. Using the whole field data, the nutrient requirement of N, P2O5 and K2O are 7.91, 3.71 and 9.21 kg for producing one quintal of mustard seed yield respectively. The contributions (%) from soil and fertilizer in an Alfisol were found to be 2.8 and 33.21 for N, 12.96 and 21.24 for P and 3.34 and 61.59 for K respectively. The average mustard seed yield was 2342 kg/ha. The average total uptake of N, P2O5, K2O and S were 147.2, 14.29, 34.58 and 17.45 kg ha-1 respectively. The mustard seed yield was found to be positively and significantly correlated with plant uptake of nutrients (N, P, K and S). Using the regression equations, fertilizer adjustment equations have been derived for attaining maximum yield, maximum profit and a desired rate of return. Using the targeted yield equations, a fertilizer ready reckoner for interpolating optimal fertilizer doses at varying soil test values has been developed for attaining seed yield target of 8,10 and 12 q ha –1. Using the initial and post harvest soil test values, applied fertilizer doses and harvested seed yields, regression equations have been calibrated for predicting the changes in soil fertility of N, P and K nutrients. The predicted soil test values are useful for prescription of soil test based fertilizer recommendations for any subsequent crop in Alfisols.