But, phosphorus and potassium presented better correlation with pseudo-second order model, considering 'R 2 ' and the values related to concentration at equilibrium time "qe" and "experimental qe" (Table ). For both nutrients there was a substantial decrease of the kinetic constant from KH2PO4 to milled samples, attesting the delay in nutrient supply after mechanochemical processing and certainly related to the formation of potassium calcium phosphate phases (K3CaH(PO4)2 and KCaPO4). Even not possible to compare kinetic constants for the calcium release, it is important to highlight that in this case was observed an opposite effect: the new phosphates phases from milling made calcium readily available. Thus, considering the kinetic behavior, it was observed that these materials would promote better nutrient management by delaying the bioavailability of phosphorus and potassium (which are highly soluble from KH2PO4) and increasing the calcium bioavailability.