Influence of Dissolved Organic Matter(DOM)on Bioavailability of Copper in Soils

The pot experiments were conducted to study the influence of the dissolved organic matter(DOM)extracted from chicken manure on the growth of cole(Brassia campestris)and Coppe(rCu)bioavailability in red soils, brown soils and black soils contaminated by copper. The results indicated that the rates of emergence of cole both in black soils and red soils decreased with the addition of DOM, while the rate of emergence of cole in red soils decreased significantly (P0.05), especially when the amount of DOM addition was more than 100 mgC·kg-1. The rate of emergence of cole in Brown soils was not significantly affected by the addition of DOM. The biomass of cole increased and then decreased with the increased amount of addition DOM in three soil types, while it reached at the peak when the DOM concentration was by 50 mgC·kg-1. In comparison with different soils, the biomass of cole ranked from high to low in turn black soil, brown soil and red soil. With the increased DOM concentration in all three soil types, both the copper concentration in cole and the available copper content in soils were gradually increased, while it reached at the peak when DOM content was 200 mgC·kg-1. Compared to three soil types, the available Cu content in red soils was significantly higher than that in black soils and brown soils with the increased added amount of DOM in soils, which might be closely related to the lower pH in red soils. Therefore, the Cu bioavailability in soils increased with the added DOM entering into soils, which indirectly affected the growth of crops and the Cu absorption by crops.