Complexing characteristics of HA with copper and zinc and their biological availability

In this paper,we studied the characteristics of complexes between Cu2+ /Zn2+and HA and their availability under field condition.The results showed that long-term fertilization resulted in a construction of soil HA more complicated,and the complexes stability of HA-Cu2+/Zn2+ more stable.Applying organic fertilizer could enhance logk value of HA-Cu2+ compared to chemical fertilizer; but the result was inversed for HA-Zn2+ in which applying chemical fertilizer had a more significant positive effect on logk.Soil HA was inclined to form mixed or mixed or polynuclear complexes with Cu2+/Zn2+.Applying organic fertilizer could increase the complexing strength and capacity of HA with Cu2+/Zn2+.However,applying chemical fertilizer could promote the activity and availability of HA-cation resulting in a reversed picture.The incubation experiment showed that applying HA treated with organic fertilizer reduced more Cu2+/ Zn2+ uptake than single application of chemical fertilizer in maize.In general,different fertilization had a more pronounced effect on Cu2+ than Zn2+ more pronounced.