Effects Of Different Organic Materials On Distribution Of Cu And Zn In Black Soil And Mechanism Study

In order to study the effects of different types of organic material on contents and fractions distribution of Cu and Zn in black soil, three types of organic materials including 8 different kinds were used, culture experiments and field experiments were combined to confirm the conclusions. During the research, fractions changes were focused on and the mechanism were also discussed. The main conclusions are as follows:(1) Livestock manures increased the total contents and fraction contents of Cu and Zn followed the order of pig manure > chicken manure > cow dung. With the increase of time, livestock manures promoted Cu transformed from high bio-availability to low availability, but instead of Zn.(2) Natural organic material increased the total contents of Cu and Zn, and there were no differences among different treatments but the growths were overall lower than livestock manures. Natural organic materials showed no consistency ruled on fractions contents of Cu and Zn, and they promoted Cu transformed from high bio-availability to low availability, which were the same with livestock manures. But in general, the effects caused by natural organic materials were lower then livestock manures.(3) Half-decomposed organic materials didn’t show the same rules on total contents of Cu and Zn. The application of peat decreased the total contents of Cu and Zn obviously, however, bacteria residue didn’t. Half-decomposed organic materials increased the contents to Oxi. and Residual fractions, decreased the contents of Aci. and Red. fractions of Cu and Zn. In addition, half-decomposed organic materials also promoted both Cu and Zn transformed from high bio-availability to low bio-availability, which were much better than livestock manures and natural organic materials.(4) The study on vertical distribution of Cu and Zn affected by different organic materials found that the total contents of Cu and Zn reduced with the increase of depth. The total contents of Cu in different depth showed the rule of chicken manure> double manures> double manures mixed with straw> cow dung> straw >CK, for Zn there was no obvious regularity. With the increase of depth, the contents of Aci. and Red. fractions of Cu reduced, while Oxi. and Residual fraction remain the same, for Zn it was Aci. fraction decreased sharply, Red. and Oxi. fractions decreased slightly, Residual fraction of Zn remain the same. Besides, with depth deepened, the differences among different treatments reduced. The bio-availability of Cu and Zn was high in surface soil but low in deeper ones. In terms of different fractions, Aci. and Red. fractions were more likely to change with the depth deepened, except for the other two fractions.(5) The research of effects of livestock manures on adsorption and desorption characteristics Zn in black soil found that adsorption quantity of Zn in black soil increased with the adsorption equilibrium concentration increased and the adsorption curve slope became smaller gradually. When th equilibrium concentration was low, there was no obvious difference among different treatments on adsorption contents of Zn, but with the increase of equilibrium concentration there comes a rule: chicken manures> pig manures> CK> cow dung> fertilizers only. Freundlich was the best equation to fix adsorption isotherms, and then is Langmuir. When the absorption liquid equilibrium concentration was high, MBC(maximum buffer capacity) can reflect the adsorption capacity of Zn with the order of chicken manures> cow dung> pig manures> CK> fertilizers only, while k’in freundilich could representative when it is low with the order of chicken manures> cow dung> fertilizers only> CK> pig manures. The desorption contents of Zn in black increased with the increased of adsorption contents. When the adsorption were higher then 2000g/kg, the desorption showed chicken and pig manures and fertilizers only were higher then CK and cow dung. Y=ax+b was perfect to fix desorption curves, whose “a” stand for soil buffer capacity to exogenous Zn and the rule for it was chicken manures> pig manures> CK> cow dung> fertilizers only.