Direct and Residual Effect of Some Indigenous Phosphate Rocks oh Berseem and Rice Grown in a Non-Acid Coarse Textured Soil

Greenhouse experiments evaluating nine indigenous phosphate rocks from Jhamar Kotra, Maton, Jhabua, Mussoorie, Singhbhum, Palamau and Kasipatnam with varying mineralogical and chemical compositions were conducted on a low P loamy sand neutral soil. Triple superphosphate (TSP) was used as standard source of phosphorus. The direct effect of phosphorus at different rates of application was tested on berseem (Trifolium alexandrinum L.) and the residual value was examined on rice. Although response of berseem, as judged by dry matter yield and P uptake, to TSP was obtained, all the phosphate rocks except the one from Maton were found ineffective as source of P. However, the residual effect of seven out of nine phosphate rocks was at par with that of TSP. The two samples of phosphate rocks which showed poor residual effect contained substantial quantities of free lime.