Assessment of potassium - supplying power of soils to crops ii. Determination of available potassium parameters of soils
1981
Simonis, A. (Soil Science Institute, Thessaloniki (Greece))
The parameters of intensity and quality of available potassium of 30 representative soils of the most important soil types of Northern Greece and their potassium buffering capacity, were determined from the Q/I relation technique. The values of equilibrium activity ratios of soil potassium ARe**k (parameter of intensity), were characteristically higher in coarse textured soils and in soils developed from acidic rocks. Their relationship with uptake was poor, but improoved considerably, when the values of the activity ratios of potassium were used in the arithmetic form: AR**k (r=0,67) as well as in the logarithmic form: pK-1/2p(Ca+Mg) (r=0,72). The values of equilibrium exchangeable potassium of soils - no.dno.k degrees (parameter of quantity), were related significantly with the total K-uptake (r=0,66) and exchangeable-K (r=0,57), but very poorly with non-exchangeable-K (r=0,29). The potassium buffering capacity values of soils (PBC**k), were significantly related to percent clay (r=0,76), to CEC of soils (r=0,60) and clay (r=0,78), to (Ca+Mg) exch. (r=0,69), to pH (r=0,63) and were generally, higher in soils developed from basic rocks than acidic rocks. Some oils, exhibiting somewhat similar AR**k - values were found to differ in their capacities to maintain K against depletion as expressed by their PBCK - values. Furthermore, some soils with low ARe**k - values released considerable amounts of non-exchangeable K, which were in good agreements with their PBC**k - values
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