The effect of organic fertilizer, composite NPK and clinoptilolite on changes in the chemical composition of degraded vertisol in western Serbia

Abstract

Over 2003-2008, a study was conducted on the combined effect of clinoptilolite commercially termed "Agrozel", organic fertilizer (cattle manure) and composite NPK fertilizer (15:15:15) on changes in the chemical composition of shallow eroded i.e. degraded vertisol in Cacak area (Western Serbia). The mineral clinoptilolite derived from natural zeolitic tuff obtained at the Katalenac deposit near Vranjska Banja (South-eastern Serbia) was used in the study. Agrozel has a particle size of 0-1.0 mm, cavity volume of about 34%, high thermal stability (600-650 degrees C), and the cation exchange capacity (CEC) of 153 mmol M+/100 g. The following fertilization treatments were employed: i) control (without fertilization), ii) A(1)= NPK (0.1 kg/m(2)) + cattle manure (5 kg/m(2)), iii) A(2) = NPK (0.1 kg/m(2)), iv) A(3) = Agrozel (1 kg/m(2)) + cattle manure (5 kg/m(2)) + NPK (0.1 kg/m(2)), and v) A(4) = Agrozel (1 kg/m(2)) + NPK (0.1 kg/m2). The obtained results showed that the combined use of fertilizers induced changes in soil chemical composition as compared to the control All treatments (A(1), A(2), A(3) and A(4)) led to increases in humus, total nitrogen (N-TOT) and, in particular, phosphorus (P2O5) and potassium (K2O) levels within all depths. The humus and N-TOT increases were not significant, as opposed to P2O5 and K2O increases that were significant relative to the control. Soil pH at all depths was significantly increased by the A(1), A(3) and A(4) treatments and decreased by the A(2) treatment. The highest increase was recorded in the 0-20 cm soil depth and the lowest in the 40-60 cm depth.