Comparative efficiency of phosphatic fertilizers on yield and its uptake in ragi - groundnu cropping sequence

摘要

The efficiency of phosphate rock (PR) in relation to soluble fertilizers is low in neutral soils as compared to acid soils. The lower efficiency of added P is due to the relatively slower rate of release of P from PR. To over come this problem, a small quantity of water soluble phosphate is added as a starter dose to supply P in the initial stage of the crop growth. A number of studies have indicated that super phosphate and rock phosphate in 1 : 1 proportion is better in neutral soils and thereby minimizing the cost involved on P fertilizers. The practice of mixing PRs and SP in the ratio of 3 : 1 or 1 : 1 has been found to be beneficial. Such a practice will be economical to the farmers towards,cost reduction on fertilizers without affecting theyield. The compaction of JPR with water soluble SSP or MAP is of recent origin and their efficacy in neutral soils, under ragi - groundnut cropping sequence is investigated in the present study.