EFFECT OF PHOSPHATE ROCK AND TRIPLESUPERPHOSPHATE ON GROWTH AND LEAF N, P AND K CONTENTS OF GROUNDNUT (ARACHIS HYPOGAEA L.) GROWN ON A CLAY SOIL

Abstract

A pot experiment was carried out to investigate the agricultural value of a local phosphate rock (PR) as a source of plant phosphorus compared with that of the currently imported triplesuper-phosphate (TSP) .The PR was applied at the rate of 0, 55, and 110 kg P2O5 /ha and the TSP was at the rate of 0, 45 and 90 kg P2O5 /ha. The growth and leaf contents of N, P and K of groundnut (Arachis hypogaea L.) grown on a clay soil were measured. The experiment continued for two sea-sons. Phosphatic fertilizers are of low recovery; therefore, they can remain for the next crop. Thus, the pots of the first season were set to study the residual effect of phosphorus in the second season. The results indicated that PR and TSP significant-ly (P>0.05) increased dry weights of shoot and root, leaf contents of N , P and available soil phosphorus. However, plant height was signifi-cantly increased by TSP only. The leaf content of K was neither affected by PR nor TSP application. The results showed a positive effect of the residual PR and TSP on the measured parameters. Moreo-ver, the results revealed that the plant measure-ments obtained from PR treatments were compa-rable to those obtained from TSP treatments which indicate that PR can be used as a potential source of phosphorus fertilizer.