抑制剂对海南土壤中硝化作用及N2O排放的影响

通过室内培养试验研究4种肥料增效剂对尿素在海南土壤中氮素转化和N₂O排放的影响，以期筛选出适合海南土壤的氮肥增效剂类型。培养试验设单施尿素（CK）、尿素 + 长效复混肥添加剂（加入尿素量的8‰，NAM）、尿素 + 双氰胺（加入尿素量的3.5%，DCD）、尿素 + 3,4-二甲基吡唑磷酸盐（加入尿素量的1%，DMPP）、尿素 + 2-氯-6-三氯甲基吡啶（加入尿素量的8‰，NMAX）5个处理。在培养过程中定期测定土壤理化性质、铵态氮和硝态氮含量以及N₂O排放量的变化，以分析不同增效剂对土壤氮素形态及N₂O排放的影响。结果表明:添加增效剂处理土壤的pH、有机质、全氮和速效钾等均与CK无显著差异，但土壤速效磷含量显著降低。培养过程中，除DCD外，DMPP、NAM和NMAX处理铵态氮浓度一直处于较低水平，而土壤硝态氮含量缓慢增长，显示出明显的硝化抑制效果。与CK处理相比，添加抑制剂处理土壤N₂O浓度峰值延后，累计排放量显著降低，但不同抑制剂间差异不显著。综合比较硝化抑制作用及N₂O减排效果，可以认为添加长效复混肥添加剂（NAM）、3,4-二甲基吡唑磷酸盐（DMPP）和2-氯-6-三氯甲基吡啶（NMAX）等抑制剂的肥料适宜应用于海南水稻土。

Effect of Inhibitor on Soil Nitrification and N_2O Emission in Hainan

The effect of four inhibitors on soil nitrification and N₂O emission in Hainan was investigated in an indoor incubation experiment to screen appropriate nitrogen fertilizer inhibitors for soils in Hainan. Five treatments were set as CK (only urea), urea plus long-term compound fertilizer additive (8‰ Urea + NAM), urea plus dicyandiamide (DCD) (3.5% urea + DCD), urea plus 3, 4-dimethylpyrazole phosphate (DMPP) (1% urea + DMPP) and urea plus 2-chloro-6-trichloromethylpyridine (NMAX) (8‰ urea + NMAX). Soil pH, ammonium-nitrogen (NH₄+-N), nitrate and N₂O fluxes were determined in the incubation. Our results showed that compared with CK, four inhibitor addition treatments didn’t significantly affect soil pH, organic matter, total nitrogen and available potassium but significantly decreased soil available phosphorus. During the incubation, NH₄+-N concentration in NAM and NMAX treatments except DCD was at low level. However, nitrate concentration increased slowly showing obvious nitrification inhibiting effects. Compared with CK, the peak of N₂O flux was delayed and accumulative N₂O emissions were significantly decreased in four inhibitor added soils. However, there were no significant differences in inhibiting effect among four inhibitor addition treatments. Therefore, given the effects of nitrification inhibition and N₂O mitigation, nitrogen fertilizers added with NAM, DMPP and NMAX were considered to be suitably applied into rice paddy soil in Hainan.