Estimation of cadmium load on Japanese farmland associated with the application of chemical fertilizers and livestock excreta

Abstract

In the present study, we estimated the cadmium (Cd) load on Japanese farmland originating from chemical fertilizers and livestock excreta. Phosphate and compound fertilizers, except for fused phosphate, contained higher concentration of Cd than the other fertilizers. Cadmium concentrations in phosphate fertilizers, cattle excreta, pig excreta, and chicken excreta were 0.04 to 5.30, 0.38, 0.50, and 0.57 mg Cd kg−1, respectively. Cadmium load associated with the application of chemical fertilizers and livestock excreta amounted to 7.034 and 2.161 Mg Cd year−1 in 1997, respectively, indicating that chemical fertilizers were the main source of Cd load on Japanese farmland. Cadmium in non-utilized livestock excreta amounted to 1.408 Mg Cd year-1 in 1997. Phosphate application derived from non-utilized livestock excreta instead of chemical fertilizers increased the Cd load level <1%. Cadmium load associated with the application of chemical fertilizers and livestock excreta accounted for 0.4% of the estimated amount of total Cd in farmland soil (2,216 Mg Cd). It was considered that the risk of an increase in the Cd concentration would be high in farmland with multiple cropping, especially in the case of vegetable and industrial crop cultivation.