Use of Soil Amendments to Reduce Nitrogen, Phosphorus and Heavy Metal Availability

The primary objectives of this study were to determine (1) the exchange characteristics of various soil amendments using a range of salt solutions, (2) the effect of selected soil amendments on heavy metal (Cu2+, Pb2+, and Zn2+) availability, and (3) the effect of selected soil amendments on NH4 + and P availability. The CEC of zeolite and red mud obtained using solutions of 0.1 M BaCl2 and 0.1 M BaCl2/NH4Cl were significantly lower than values obtained using 1 M KCl and 1 M NH4Cl. The higher CEC obtained with monovalent cations indicated that larger divalent cations could not enter the mineralogical framework of zeolite and red mud, and, consequently, a number of exchange sites were only accessible to the smaller monovalent cations. These findings suggest that 1 M KCl and 1 M NH4NO3 should be used as the extracting solutions to obtain the best estimation of CEC and ECEC of red mud and zeolite. The ability of red mud, zeolite, and calcium phosphate (Ca-P), mixed at rates of 0%, 5%, 10%, and 20% (w/w), to ...