ABSTRACT
Quantity-Intensity (Q/I) parameters were used for elucidating the role of buffering properties of soils through K depletion. Winter wheat was sown in a greenhouse pot experiment until K-depletion and soils were analyzed with NH4OAc and NaBPh4 (1 min incubation period). Q/I isotherms (partitioned in exchangeable and non-exchangeable form) were constructed for the soils before and at the end of the K-exhaustion experiment. Results showed that NaBPh4-K correlated better than NH4OAc-K with intensity parameter (AReK) or labile K (-ΔΚ0) in K-depleted soils (r = 0.41 and 0.70), indicating the importance of non-exchangeable K in K dynamics. The latter was confirmed from the comparison of buffering characteristics between initial and K-depleted soils which showed that among the soils studied there was a group whose increase in buffering capacity (PBCKt) was due to non-exchangeable K fixation. Furthermore, NaBPh4-K was well predicted by the sum of exchangeable K and the quantity of K that has to be applied to achieve K balance as derived from Q/I isotherms (EK0 + CK0). Finally, relationships were found between Q/I parameters of the initial soils (-ΔΚ0i, ΕΚ0i, ΕΚri, CK0i) and the K-depleted ones (ΕΚrd, ΕΚ0d, CK0d, CKrd) which allowed corresponding prediction of the initial parameters (r2 = 0.78–0.87).
Disclosure statement
No potential conflict of interest was reported by the authors.