Use of cheaper and efficient sources of phosphatic fertilizer for cowpea In rice fallows

Abstract

An experiment was conducted in a farmer's field at Kalliyoor in Trivandrum District with a view to study the effect of different cheaper sources of phosphorus application on growth, yield and composition of cowpea. The residual effect of these sources of phosphorus was also studied by raising a paddy crop during the subsequent season. The trial was laid out in a randamised block design with five treatments and four replications. The treatments included Mussoorie phosphate, Udaipur phosphate, rock phosphate (Madhya Pradesh) and single superphosphate. The subsequent trial was laid out in split plot non-factorial structural design with five mainplots, two subplots and four replications. The study revealed that phosphorus application significantly influenced the growth characters of cowpea viz. plant height, number of leaves per plant and number of branches per plant. Yield contributing factors viz. number of pods per plant and grain yield per plant were also significantly increased by different sources of phosphorus. Application of superphosphate resulted in heighest value for all these yield characters of cowpea. Maximum grain yield of 658 kg/ha could be obtained from the superphosphate treatment and this was followed by Mussoorie phosphate. Studies on the effect of residual phosphorus on the subsequent paddy crop indicated that height of plant and the tiller number per plant at maximum tillering stage and grain ripening stage were significantly influenced by rock phosphate application. The yield contributing factors such as number of filled grains per panicle, thousand grain weight and grain yield of paddy were also significantly influenced by the residual effect of rock phosphates applied to cowpea plus superphosphate applied to paddy than that of superphosphate alone applied to both cowpea and paddy.