Investigation on Phosphorus Fractions and its use efficiency in Rice (Oryza sativa L.) under Integrated Phosphorus Management System

A field experiment was conducted at Faculty of Agriculture, Wadura during the two consecutive kharif seasons of 2008-09 and 2009-10 for “Investigation on phosphorus fractions and its use efficiency in rice (Oryza sativa L.) under integrated phosphorus management system”. The experiment was laid out with 18 treatment combinations viz. three levels of inorganic phosphatic fertilizer (0, 30 and 60 kg P2O5 ha-1), three levels of organic manures (control, FYM @ 15 t ha-1 and PM @ 5 t ha-1) and two levels of biofertilizers (uninoculation and inoculation with PSB) in randomized complete block design with three replications. The results revealed that grain and straw yield of rice increased significantly with increase in recommended dose of phosphatic fertilizer. Application of PM @ 5 t ha-1 showed significantly superior results over other organic treatments. Inoculation with PSB showed significantly superior results over no inoculation. Yield attributing characters viz. number of effective tillers, number of spikelets, panicle length and 1000-grain weight showed significant increase with increasing levels of phosphatic fertilizer. The plant analysis showed significant increase in nutrient content (N, P, K and Zn) in grain and straw with application of recommended inorganic phosphatic fertilizer. Among organics, PM @ 5 t ha-1 showed superior results over FYM @ 15 t ha-1. Inoculation with PSB also showed significantly superior results for nutrient content (N, P, K and Zn) over control. Application of recommended inorganic phosphatic fertilizer significantly increased the soil P-fractions (Fe-P, Al-P, Ca-P and total P), available N, P, K and Zn content at harvest. Application of FYM @ 15 t ha-1 and PM @ 5 t ha-1 significantly increased various P-fractions (Fe-P, Al-P, Ca-P and total P) and also available N, P, K and Zn in soil at harvest over control. Inoculation with PSB showed significant increase in available N, P, K and Zn and P-fractions (Fe-P, Al-P, Ca-P and total P) over control. Organic manures enhanced the physico-chemical properties of the soil such as pH, EC, OC and CEC. Among organics PM @ 5 t ha-1 was found superior over FYM @ 15 t ha-1. Inoculation with PSB significantly improved soil physico-chemical properties over no inoculation