不同浓度DMPP和DCD对石灰性土壤中氮素转化的影响

【目的】研究不同浓度硝化抑制剂3,4-二甲基吡唑磷酸（DMPP）和双氰胺（DCD）对石灰性土壤中氮素转化的影响，筛选出适宜石灰性土壤施用的DMPP和DCD最佳浓度，为其进一步在生产实践中的施用提供参考。【方法】采用室内培养的试验方法，在相同培养条件（土壤水分含量为田间持水量（WHC）的60%，温度为25℃）下，通过测定不同浓度DMPP（含氮量的0.5%、1%、2.5%和5%）和DCD（含氮量的2.5%、5%、10%和15%）处理土壤中各种形态氮素含量，评价不同浓度DMPP和DCD的抑制效果。【结果】施加不同浓度DMPP和DCD的土壤铵态氮含量均显著高于CK，而硝态氮和亚硝态氮含量显著低于CK。石灰性土壤中施用DMPP和DCD均能显著降低土壤的氨氧化速率，土壤铵态氮的半衰期从CK处理的3.6 d分别增加到14.1-17.1 d和13.1-26.8 d。不同浓度的DMPP间氨氧化速率差异不显著；而DCD处理的氨氧化速率随其浓度的增加而下降，亦即土壤铵态氮浓度的半衰期随施用浓度的增加而显著增加。除CK外，各处理氨氧化速率常数k相比，以2.5%DCD最小，15%DCD最大；DMPP与DCD相比较，除DCD最低浓度处理外（2.5%），所有DCD处理的氨氧化速率均大于DMPP。【结论】硝化抑制剂DMPP和DCD均能显著抑制铵态氮向硝态氮的氧化进程，DMPP各浓度处理抑制效果差异不显著，DCD各浓度处理间差异显著，5%DCD与DMPP各浓度处理间无显著差异。因此，建议DCD的施用量为含氮量5%，而DMPP的施用量为含氮量的0.5%。

Effects of Different Application Rates of DMPP and DCD on Nitrogen Transformation in Calcareous Soil

【Objective】A simulating experiment was carried out to study the effects of different concentrations of DMPP and DCD on nitrogen transformation in calcareous soil, and the best application rate was screened to provide references for agricultural practice.【Method】In the same incubation condition (soil moisture: 60% of water hold capacity, 25℃), the effects of different concentrations of DMPP (0.5%, 1%, 2.5% and 5% of applied pure N) and DCD (2.5%, 5%, 10% and 15% of applied pure N) on nitrogen forms in calcareous soil were compared.【Result】The results showed that compared to CK, the contents of soil ammonium nitrogen in DMPP and DCD treatments were higher, while nitrate and nitrite nitrogen concentrations were significantly lower. Application of DMPP and DCD could significantly (P＜0.05) decrease the ammonium oxidation rate and the half-lives of NH4+ in soils increased from 3.6d in CK treatment to 14.1-17.1 d in DMPP treatments or 13.1-26.8 d in DCD treatments. No significant difference in the ammonia oxidation rates was observed in different DMPP treatments, however, the rates decreased with the rising of DCD concentrations. Among all nitrification inhibitor treatments, the minimum ammonia oxidation rate was found in 2.5% DCD treatment, while the maximum rate was observed in 15% DCD. The ammonia oxidation rates in DCD treatments (except 2.5% treatment) were higher than those in DMPP treatments. 【Conclusion】Application of DMPP and DCD could inhibit the oxidation of ammonium. No significant difference was observed in DMPP treatments, whereas an evident dose-effect relationship was found in DCD treatments. No significant difference was found between 5% DCD treatment and DMPP treatments (P＜0.05). As a result, the recommended DMPP and DCD rate in carcalous soil was 0.5% and 5% of pure nitrogen, respectively.