Potassium behaviour in some alluvial soil series of Pakistan
1992
Ranjha, A.M. | Mehdi, S.M. (University of Agriculture, Faisalabad (Pakistan). Dept. of Soil Science) | Qureshi, R.H. (Soil Salinity Research Inst., Pindi Bhattian (Pakistan))
Profiles of eight soil series were exposed and after complete description, the clay mineralogical composition, potassium fixation and response of applied potassium were assessed. Mineral identity of clay fraction was established by X-ray diffractometry. There was an increasing tendency of K fixation with increasing K application from 50 to 150 mg per kg and clay content in soil. Illite was the major mineral in all the soil series. Other 2:1 type clay minerals were variable in amounts. There was significant response of wheat to applied K (at 50 and 75 mg per kg) in all soil series having clay contents up to 20 and lN NH4 OAc extractable K up to 120 m K per kg soil. Potassium released by extractions like H2O, lN NH4 OAc, 0.5N MgOAc, 0.025N CaC12 and lN HNO3 was studied in three soil series. Higher correlation (r=0.9840 between lN NH40Ac extractable K and plant uptake was noted where no NP fertilizers were applied. 0.025N CaC12 gave higher correlation values (0.936 and 0.815) for 75-22 and 100-33mg NP per kg soil, respectively.
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