Influence of Phosphate Fertilizer on Cadmium in Agricultural Soils and Crops

Phosphorus fertilizers contain cadmium (Cd) as a contaminant at levels varying from trace amounts to as much as 300 mg Cd kg−1 of dry product and therefore can be a major source of Cd input to agricultural systems. Cd will accumulate in the soils if the amount added in fertilizer is greater than what is removed by crop harvest or through other loss pathways such as erosion, bioturbation, or leaching. Phosphate fertilizer may also influence Cd phytoavailability through fertilizer-induced changes in soil pH, osmotic strength of the soil solution, zinc (Zn) availability, soil organic matter, rhizosphere chemistry, soil microbial activity, and plant growth. As both total Cd input into the soil and fertilizer-induced changes in soil properties are a function of the rate of fertilizer application, management practices that improve fertilizer use efficiency should be adopted to minimize fertilizer inputs while maintaining crop yield potential. Cd accumulation in the food chain is a major international concern. Chronic Cd toxicity may occur from long-term consumption of foods containing excess levels of Cd, possibly resulting in adverse health effects including kidney tubule dysfunction and reduced bone density (Godt et al. 2006). Plants will accumulate Cd from the soil with the amount of uptake depending on a wide range of factors including soil Cd concentration, soil chemical, physical, and biological characteristics, weather, agricultural management practices, and crop genetics (Grant et al. 1999, 2008; Sheppard et al. CONTENTS