[Health-quality problems of paddy soil in the Taihu region]

The concept of soil health quality was discussed from the angle of sustainable and safe agricultural production and nutritive agricultural products. Based on the data of 13 higher-yield rice-farms and its corresponding irrigated rivers in the Taihu region, problems of health quality occurred in paddy soil were discussed. Owing to the high application of inorganic fertilizers in those farms, high available P and N were observed in paddy soil and river sediments. The contents of heavy metals such as Pb, Cu, Ni and Co in paddy soil were still at the level of background values. However, it was found that some rivers were seriously polluted by Cu, Zn and Pb. Several cases of point-source pollution of heavy metal were found in paddy soil in the region. The contents of DDT and HCH in soils and river sediments were lower than their maximum allowable concentrations. The results of lower selenium content in agricultural product owing to lower content in paddy soil indicted that the Taihu region is a selenium-deficient area.