黄土高原地区连续施锌条件下土壤锌的形态及有效性

 采用连续浸提形态分级方法，研究了连续施用锌肥后锌的土壤化学特性变化。结果表明，经过17年连续施用锌肥，锌在土壤中有明显的累积。0～60 cm各土层土壤全锌和有效锌（DTPA-Zn）含量均高于对照，并且表现出锌在表层土壤（0～15 cm）累积和向深层土壤迁移的特点。土壤中的锌主要以矿物态锌存在，占土壤全锌含量的95.57%～99.11%。其次为松结态锌，约占全锌的0.82%～3.58%。其它形态锌占全锌的比例很小，不到1.00%。锌肥施入土壤后各形态锌的含量都有较大幅度的增加，施入土壤中的锌有很大一部分转化为矿物态锌，只有一小部分进入土壤溶液，或与有机质、碳酸盐及氧化锰相结合。在土壤各形态锌中，交换态、松结态和碳酸盐态锌均能不同程度反映土壤锌的有效性。长期施用锌肥改善了小麦的锌营养状况，促进了小麦对锌的吸收，施锌小麦各器官锌含量和吸锌量均高于对照。

Zinc Fractions and Availability in the Soil of the Loess Plateau After Long-Term Continuous Application of Zinc Fertilizer

Based on the long-term location experiments, the chemical characteristics of zinc under the condition of 17 years' continuous application of zinc fertilizer were studied by using a sequential extraction technique. The results showed that zinc has accumulated in soils after continuous application of zinc fertilizer for 17 years. The total and DTPA extractable zinc in 0-60 cm soil were higher in zinc treated soil than that in the control. In addition, after long-term application of zinc fertilizer, zinc has accumulated in surface soil and transported to deep soil. In soil zinc fractions, mineral bonded zinc accounts for 95.57%-99.11% of total zinc and organic matter loosely bonded zinc accounts for 0.82%-3.58% of total zinc. Zinc fractions studied in the experiments all increased in zinc fertilizer treatment compared with the control. The result also suggested that most zinc added to soils has entered into soil minerals and little has entered into soil solutions or combined with soil organic matter, carbonate or manganese oxides. The correlation and principle component analysis suggested that the exchangeable zinc, the organic matter loosely bonded zinc and the carbonate bonded zinc could indicate the availability zinc in soils, respectively. Long-term application of zinc fertilizer also improved the nutrient condition of wheat, which accelerated the absorption of zinc by wheat. The zinc contents and uptake amounts in each organ of winter wheat was higher in zinc treatment than that in the control.