Impact of Long-term Phosphate Application and Level of Fertilizer Cd on Crops and Soils

Public concern regarding the transfer of cadmium (Cd) from phosphorus (P) fertilizers to soils, and uptake by crops, has increased interest in evaluating the true impact of fertilization practices on food nutrient content. The objectives of the study are: 1) determine the cumulative impact of applying fertilizer P, varying in Cd concentration, on grain yield and micronutrient concentration, total soil Cd, phyto-available Cd, and grain Cd concentration, on a range of soil types; 2) determine the impact of soil characteristics on availability of native soil Cd and Cd added with P fertilizer, and; 3) determine the effectiveness of several soil testing methods in predicting availability of native and applied Cd across a range of soil types and environmental conditions.

Lab studies were initiated to evaluate the impact of additions of monoammonium phosphate (MAP) fertilizer, varying in Cd concentration of 0.38, 7.3, and 211.0 mg Cd/kg of fertilizer, on soil solution and plant uptake of Cd. The study found very little relationship between Cd added to soils and Cd found in plants. Even where the concentration of Cd added to soil varied to a large degree, only small increases in solution Cd were observed. Adding the equivalent of 15 years of fertilizer MAP to soils did not result in a drastic increase in soil solution Cd, even when very high Cd concentrations were used. MB-16