Fertilizer recommendation based on soil test crop response for high targeted yield

Soil test crop responses (STCR) studies were conducted with rice cv. ADT 43 at the Experimental Farm, Annamalai University, Annamalainagar. The field consisted of four strips(I, II, III, IV) and received N₀P₀K₀,N_1/2,P_1/2,K_1/2 N₁P₁K₁,N₂,P₂K₂ fertilizers, respectively. The results indicated that the grain yield in strip I (2.36 tha⁻¹) increased to strip IV (5.69 tha⁻¹) with graded levels of NPK fertilizers due to better nutrient uptake. Followed by test crop (STCR) experiment was carried out with rice cv. ADT 36 in the same field during wet season. By using grain yield, initial soil test values, uptake of nutrients and fertilizer doses applied, the three basic parameters viz., NR,CS,CF were worked out, Fertilizer adjustment equations(FAEs) were formulated. Finally the fertilizer recommendations were worked. The results of this STCR experiment revealed that when the initial soil available NPK status were 200, 10, 250 kgha⁻¹, the FN,FP₂O₅,FK₂O recommendations to get 60 t ha⁻¹ were 233:100:107 kgha⁻¹ for fertilizers alone application. The fertilizer recommendations for the application of fertilizers + FYM + Azospirillum, for the same yield target were 185:86:82 kgha⁻¹ due to balanced fertilization.