Soil test based phosphorus recommendation for potato

Field experiments were conducted at twelve centers of All India Coordinated Research Project on Potato representing different agro climatic zone to find out suitable dose of P in potato based on soil test during 2005-06 and 2006-07. Four treatments consisting of combinations of different levels of P based on soil test used in the study showed significant effect on yield of potato. Results revealed that soil having low P availability (= 10 ppm) responded to P fertilizers and there was a need of P application at all these centers 100-125% recommended dose of P gave best tuber yield and also net returns. In case of medium P availability soils (10 to 22 ppm), the 50-100% recommended dose of P fertilizer was found to meet P need of the crop and gave higher yield and also net returns. In case of high P status soils (= 20ppm), application of P did not respond by increased yield and 25% of recommended dose of P as maintenance dose in the soils with > 20 ppm P gave maximum tuber yield. The results clearly indicate that P may be applied based on soil test value across different agro climatic zone to economize P dose.