Abstract:
Laboratory and pot experiments were conducted with some low activity Clay Soils in Benue
State to evaluate their potassium (K) supplying capacity using equilibrium parameters as
measured by quantity, intensity and activity indices. The soils were Daudu, Tse-Kough, TseAgbakor
and Mbachor. Farmers' fields were used to verify the findings of these experiments.
Routine Soil analysis was done using standard procedures. K fractions were estimated using the
procedure of Pratt, (1965). The Total K content of the Soils varied from 57.06 C mol Kg-1 at
Daudu to 64.63 C mol Kg-1 at Mbachor with the non-exchangeable K constituting 57.16%,
0.40% and 0.13% respectively of the total K in the Soils. The potassium buffer capacity (PBC)
which measures the ability of the Soils to maintain K intensity in solution ranged from 1.98 at
Daudu to 3.56 at Mbachor indicating a slow release of K in these Soils. The specifically bonded
K which constituted the bulk of the labile K (KL) was generally low. Response of Soybean
(Glycine max merr. (L) to K application was observed in all the Soils studied and the critical K
value for optimum yield of the crop using the procedure of Cate and Nelson , (1965) was
determined to be 0.33 C mol Kg-1. Available K and fixed K showed no relationship with the
parameters studied. A positive and significant relationship was observed between Non
Exchangeable K and Available K (r = 0.989*). Mineral K showed a Positive and significant
relationship (0.993**) with Available K. Total K had a positive and significant relationship (r =
0.986*) with below ground tissue K. It was concluded that response of Soybean to K application
would be probable in the Daudu and Tse-Kough Soils while response to K application will not be
probable with the Tse-Agbakor and Mbachor Soils |
