Cadmium in fertilizers
Phosphorus is one of the key nutrients needed by plants to grow. Many soils , in particular in developing countries, are deficient in phosphorus, leading to stunted growth, drying of the leaves, slow ripening processes, and poor filling of grain.
In many developing countries, the amount of phosphorus applied to crops (from manure or mineral fertilizers ) is well below the quantity being removed by crops and erosion, leading to a progressive impoverishment of the soil and reduction of yields.
While phosphorus is important for plants, and hence for people, cadmium contained in phosphorus sources can be detrimental. In fact, the quantity of cadmium contained in a phosphate fertilizer depends on the source of the rock from which it was made. This content varies from almost zero to over 300 mg Cd/kg P205. With current processes, much of the cadmium in the rock passes into the phosphate fertilizers produced from it.