抑制剂对淹水土壤反硝化和氨挥发的影响

通过室内培养试验，设置3个硝化抑制剂双氰胺（DCD）（氮肥用量的2.5%（DCD1）、5.0%（DCD2）、7.5%（DCD3）），3个脲酶抑制剂氢醌（HQ）（氮肥用量的0.1%（HQ1）、0.3%（HQ2）、0.5%（HQ3））和3个硝化抑制剂DCD+脲酶抑制剂HQ联合施用（氮肥用量的2.5%+0.1%（HH1）、5.0%+0.3%（HH2）、7.5%+0.5%（HH3））试验处理，探讨抑制剂联合施用对淹水土壤反硝化和氨挥发过程及其环境因子的影响，并借助通径分析探讨环境因子对反硝化和氨挥发过程的影响程度，探求抑制剂、氮素转化过程及其环境因子之间定量影响关系.结果表明，单独施用硝化抑制剂DCD能显著减少反硝化速率，但是增加氨挥发损失.单独施用脲酶抑制剂HQ能不同程度减少氨挥发损失，但对反硝化作用效果不稳定.而联合施用DCD和HQ，尤其是HH2（5.0%的DCD+0.3%的HQ）联合施用可有效地同时抑制反硝化和氨挥发损失，相比CK，其反硝化和氨挥发速率分别减少31.3%和12.5%.通径分析发现，硝化抑制剂DCD和脲酶抑制HQ主要影响土体NO₃^--N和NH₄⁺-N浓度、上覆水体NH₄⁺-N和DON浓度，从而影响反硝化和氨挥发速率.

Effects of inhibitors on denitrification and ammonia volatilization in submerged soils

Three nitrification inhibitors treatments,2.5% (DCD1), 5.0%(DCD2) and 7.5%(DCD3) of nitrogen fertilizer application, and three urease inhibitors treatments, 0.1% (HQ1), 0.3%(HQ2), 0.5%(HQ3) of nitrogen fertilizer application, and three combined nitrification and urease inhibitors treatments, 2.5%+0.1% (HH1), 5.0%+0.3%(HH2), 7.5%+0.5% (HH3), were experimented in this study to investigate the influence of inhibitors on denitrification and ammonia volatilization losses in laboratory experiment. The quantitative influence relationship among inhibitors, nitrogen losses (denitrification and ammonia volatilization) and environmental factors were further explored using path analysis method. The results showed that application of dicyandiamide alone could significantly inhibit denitrification loss, but increase NH₃ volatilization. Application of hydroquinone alone could effectively inhibit NH₃ volatilization, but had ineffective effects on denitrification loss. Combined application of dicyandiamide and hydroquinone significantly inhibited both denitrification loss and ammonia volatilization, especially at HH2 (5.0% dicyandiamide +0.3% hydroquinone. Compared to CK, HH2 decreased the denitrification and ammonia volatilization losses by 31.3% and 12.5%, respectively. Path analysis showed that dicyandiamide and hydroquinone mainly decreased the sediment NO₃^--N, sediment NH+ 4-N, overlying water NH+ 4-N and overlying water DON concentration, and thus decreased denitrification and ammonia volatilization rate.