Fertility Studies on a Sandy Loam in Semi-Arid Tanzania

Abstract

SUMMARYInitial and residual effects of phosphorus, lime and potassium were studied on Natal Common and Dodoma Bold groundnuts. Double superphosphate (D.S.P., 42% P2O5) considerably increased yields of the first two crops. Lime was noticeably beneficial on Dodoma Bold but less so on Natal Common, while K depressed yields of both when applied without P. The LPK treatment yielded best with each variety, but initially P alone was most economic. Comparing D.S.P., Tororo superphosphate (T.S.P., 21% P2O5, 13% S) and Minjingu phosphate (M.P., 15% citric soluble P2O5), T.S.P. gave the best response (625 lb/acre over 3 years), more than double that of equivalent P2O5 as D.S.P. T.S.P.'s superiority is attributed mainly to its sulphur content. Though initially inferior, M.P. proved as good as D.S.P. over 3 years. 224 lb/acre T.S.P. in alter-nate years is recommended. After two or three crops, light applications of lime and potassium together would be beneficial.