Effect of Long-Term Fertilization on Accumulation of Cadmium in Soil-Crop System

In order to understand the effect of long-term fertilizer application on accumulation of cadmium (Cd) in Typic Purpli-Udic Cambosols and its crop, a research was carried out by a 15 years´ long-term fix experiment in Chongqing, China. The results showed that Cd accumulated evidently in topsoil of 0-20cm, which content was in range of 1.6-2.7mg/kg and exceeded the third standard of national soil environmental quality after 15 years´ fertilization. The total Cd content in topsoil was increased for 30.9% but it changed little in plow pan. Available Cd content in topsoil was also increased, especially in the treatment of phosphorus fertilizer application, which content was higher for 23.4% than that in control treatment (CK). The order of Cd forms in soil was RES(58.5%)> EX (18.1%) > Fe-Mn (14.2%) > CAB (9.2%). The Cd forms of EX and CAB in soil were influenced by different fertilizer application. K fertilizer application could increase the content of EX Cd in soil. Combination application of fertilizer and organic manure obviously reduced the content of CAB Cd in soil. Compared with CK, Cd contents in wheat and in rice grain were increased obviously by long-term fertilizer application. The content of Cd in wheat and in rice was increased by P and K fertilizer application. The Cd content in rice grain of P fertilizer treatment exceeded the national food safety standard of 0.2 mg/kg; but the Cd content in wheat grain did not exceed temporarily.