Saturday, 15 July 2006

Efficient Use of Fertilizer Phosphorus in Crops in India.

Rayappan Kumaresan1, Nassir. A. Abderrahim Nassir2, and Tayub Tayub Mrabet2. (1) Tamilnadu Agricultural Univ, Dept of Soil Science and Agricultural Chemistry, Coimbatore, 641003, India, (2) World Phosphate Institute, IMPHOS, Casa Blanca, Morocco

The decline in growth rate of food grain production has been observed in response of deterioration in soil health owing to improper P fertilizer practices. There is a concern that a large number of farmers of this tract in India were applying inadequate, imbalanced, non-integrated fertilizers. The N:P use ratio of this tract was 2.6:1.0 during 1999-2000 which has increased to 3.0-1.0 during 2002-2003 indicating imbalanced P fertilization resulting in 20-40% yield reduction in groundnut, cowpea and black gram crops. The effect of balanced use of P fertilizer to maximize economic returns in groundnut, cowpea and black gram was studied through several field demonstrations in the farmer's fields in India during 2004. The soils represented Inceptisol, Alfisol and Vertisol in Tamil Nadu (India). The soils were fine loamy calcareous to coarse loamy, with low and medium available P status. The treatments for groundnut crop were farmer's practice (N-P-K 17-17-17 kg ha-1 complex), No phosphate (N-K 17-54 kg ha-1), recommended (N-P-K 17:34:54 kg ha-1) (P as Single Super Phosphate (SSP)) and Integrated Plant Nutrient Supply (IPNS) N-P-K 30-60-120 kg ha-1 (P as SSP + phosphobacteria 2 kg ha-1. The treatments for cowpea and black gram were farmer's practice (25 kg ha-1 N alone), recommended NP (25 kg ha-1 N + 50 kg ha-1 P as SSP) and improved NP (25 kg ha-1 N + P 62.5 kg ha-1 as SSP). The varieties used were VRI-5 groundnut, CO2 cowpea and TMV-1 black gram. In groundnut, the highest pod yield of 1900 kg ha-1 was recorded the IPNS method. The pod yield increase over farmer's practices was 45%, with a net profit of 16500 INR ( US $366) likewise the highest pod yield in cowpea was 1450 kg ha-1 and in black gram 1320 kg ha-1 with net profit of 16100 INR (US $357 ) and 12400 INR (US $275), respectively with application of 62.5 kg ha-1 phosphorus . The IPNS method in groundnut increased level of applied P in cowpea and black gram increased the net profit to the farmers.

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