AVAILABILITY OF CADMIUM AND ZINC AS AFFECTED BY THE USE OF REACTIVE PHOSPHATE ROCK, LIME, AND CHICKEN MANURE ON AN INDONESIAN ACIDIC UPLAND SOIL UNDER FIELD CONDITIONS
Sri Rochayati1,2, M. Verloo1, and G. Du Laing1
1 Department of Applied Analytical and Physical Chemistry, Laboratory of Analytical Chemistry and Applied Ecochemistry, Ghent University, Ghent, Belgium
2 Indonesian Soil Research Institute, Bogor, Indonesia
We assessed cadmium (Cd) and zinc (Zn) availability when applying reactive phosphate rock (RPR) in combination with lime and chicken manure on Indonesian acidic upland soils. Maize plants were grown on unamended soil and soils treated with several combinations of 2 tons dolomite ha-1, 2 tons of chiken manure ha-1, 1 ton ha-1 of RPRL (reactive phosphate rock containing 4 mg Cd kg-1 and 224 mg Zn kg-1), and 1 ton ha-1 of RPRH (RPR containing 69 mg Cd kg-1 and 745 mg Zn kg-1). In addition to its positive effect on plant yield, application of RPR in combination with chicken manure did not result in toxic Cd concentrations. Although liming is effective to reduce plant Cd concentrations, it results in more soil Cd accumulation and more plant Zn deficiency. Cadmium and Zn concentrations in shoots and grains can be predicted well from amounts extracted from the soil by 0.5 M ammonium (NH4) acetate + 0,02 M ethylenediaminetetraacetic acid (EDTA) at pH 4.65.
Keywords: Acidic upland soil, fertilizer, liming, metal availability, organic matter, phosphate rock