氮锌交互作用对黄棕壤锌形态的影响

选用南方牧场土壤，在盆栽条件下，研究了氮锌交互作用对土壤中锌形态和生物有效性的影响。结果表明：(1)随施氮(NH4)2SO4]水平增加土壤pH显著降低。在不施锌或低量施氮条件下，施氮对速效锌影响不大；施锌条件下，高水平施氮显著提高了土壤速效锌含量。(2)随施锌水平增加，交换态锌、松结有机态锌、氧化锰结合态锌、无定形氧化铁结合态锌、紧结有机态锌所占比例明显增加，晶形氧化铁结合态锌及残留态锌所占比例明显下降：随施氮水平增加，土壤中交换态锌所占比例显著增加，松结有机态锌亦呈增加趋势。氮锌配施对土壤中交换态锌含量有协同效应，从而提高了锌对牧草的有效性。试验结果对南方牧场合理施肥具有指导意义。

Effects of Interaction between Nitrogen and Zinc on Forms of Zinc in Yellow-Brown Soil

Effects of interaction between nitrogen and zinc on forms of zinc in yellow- brown soil collected from a pasture in southern China were studied under pot- culture conditions. The results showed that pH of the soil was remarkably decreased with the increase rate of applied N- . Applied N had no effect on available zinc either with no zinc application or with low dose of applied N, but high level of N application obviously increased available zinc in the soil with zinc application. With increased rates of zinc application, the proportion of extractable (Ex- Zn), loosely organic matter bound zinc (LOM- Zn), manganese oxide- bound zinc (MnO- Zn), amorphously iron oxide- bound zinc (AFeO- Zn), tightly organic matter bound zinc (TOM- Zn) obviously increased and the proportion of crystalline iron oxide- bound zinc (CFeO- Zn), residual zinc (Res- Zn) in total zinc of the soil obviously decreased. With increased rates of nitrogen application, the proportion of Ex- Zn in total zinc of the soil significantly increased and so did for LOM- Zn. It was concluded that combined application of zinc and nitrogen had a synergism effect on Ex- Zn content and, therefore, increased the availability of soil zinc to plants. It may be suggested that the present experimental results be a guidance for wise fertilization in southern pastures.