Saturday, 15 July 2006

Relative Efficacy of Graded Levels of Coated Diammonium Phosphate in Groundnut (Arachis hypogaea L.).

Gopalakrishnan Mylesamy, Dept of Soil Science and Agricultural Chemistry,Tamil Nadu Agricultural Univ, Lawley Road Post, Coimbatore, India and Subbiah Karuppan, Agricultural Research Station, Tamil Nadu Agricultural Univ, Tamil Nadu, Kovilpatti, India.

Two field experiments were conducted adopting factorial randomized complete block design with three replications and the treatments consisting of three sources of P viz., coated diammonium phosphate, uncoated DiAmmonium Phosphate (DAP) and Single SuperPhosphate (SSP) and five levels of P viz., 0, 17, 25.5, 34 and 42.5 kg ha-1. The experimental field soil was neutral in reaction, non-saline, non-calcareous and sandy loam belonging to the soil group Typic Ustropept. The groundnut crop (Cultivar CO 2) was raised under irrigated condition during December 2002-April 2003 and July-October 2003 seasons. The recommended fertilizers schedule to groundnut was 17: 34: 54 kg N, P2O5, K2O ha-1. All the fertilizers were applied as basal placement. Gypsum was applied @ 400 kg ha-1 on 40-45th day after sowing and the quantity of gypsum applied to SSP plots were adjusted by taking into account the S content of gypsum and SSP. The coated DAP was superior to DAP and SSP in enhancing the pod and haulm yield. The enhancement of pod yield of groundnut by coated DAP was 76 and 91 kg ha-1 compared to DAP and SSP respectively. The superiority of coated DAP over DAP and SSP could be explained on the basis of its characteristic properties of coating materials, its profound influence on the P availability and providing it to meet the crop demand at the early period of crop growth and at the same time maintaining the higher P availability for a longer period of time. The increased P supply had increased the hundred kernel weight, oil and crude protein content and were maximum at 42.5 kg P2O5 ha-1; however the hundred kernel weight and oil content of groundnut kernel was comparable among the three sources. The coated DAP was superior in increasing the crude protein content in comparison to DAP and SSP.

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