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【目的】田间条件下氮肥中添加硝化抑制剂双氰胺(dicyandiamide,DCD)对氧化亚氮排放和硝态氮含量变化的影响尚不清楚,研究不同施氮模式对玉米产量、氧化亚氮排放以及对土壤深层硝态氮残留和氮肥农学效率等的影响,对提高氮肥利用效率、减少农业源温室气体排放具有重要意义。【方法】试验于2013年4月至2014年9月,在中国科学院长武黄土高原农业生态试验站进行,供试作物为春玉米,品种为先玉335,半覆膜种植。试验设4个处理:传统施氮(Con)、减量施氮(Opt)、减量施氮+硝化抑制剂(Opt+DCD)、不施氮(N0),定期采集土样和氧化亚氮气体,利用流动分析仪和气象色谱仪测定土壤矿质氮和氧化亚氮的含量,采用SAS软件对不同处理的产量和各个指标进行方差分析。【结果】Opt和Opt+DCD在保持产量的同时,显著影响氧化亚氮排放和硝态氮残留。Opt处理的硝态氮含量峰值降低13.7%,而Opt+DCD处理降低硝态氮峰值19.0%。其次,施氮模式还影响硝态氮峰值出现的时间:Con(190.1 mg/kg)率先出现,其次是Opt(164.0 mg/kg)和Opt+DCD(132.9 mg/kg)。Opt显著降低了氧化亚氮的排放,降幅为29.4%,而在Opt基础上添加DCD可进一步降低氧化亚氮排放28.1%。在雨季,硝态氮含量和氧化亚氮排放随降雨而出现波动。尽管Opt降低了铵态氮峰值,但在Opt基础上,添加DCD提高了铵态氮峰值。4种施氮模式土壤剖面0—100 cm和100—200 cm的硝态氮残留量分别介于33.5 148.9和24.8 92.8 kg/hm2之间,平均值分别为78.5和56.4 kg/hm2。土壤剖面0—200 cm的硝态氮残留量以Con最大,为225.9 kg/hm2,与Con相比,Opt和Opt+DCD的硝态氮残留量降幅分别为48.0%59.0%、29.4%57.5%。Opt和Opt+DCD之间硝态氮残留差异不显著(P>0.05)。【结论】不同施氮模式对玉米产量、矿质氮和氧化亚氮的动态变化以及氮肥农学效率具有显著影响,但是Opt和Opt+DCD在施氮量减少20%的同时,不仅没有显著降低玉米产量,还进一步降低了土壤剖面硝态氮的残留量和农业源温室气体的排放。因此在黄土高原雨养农业区,添加DCD是一种科学有效的施肥管理方式。
【Objective】 The effects of dicyandiamide (DCD), a nitrification inhibitor, on the changes of nitrous oxide emission and nitrate nitrogen content in nitrogen fertilizer under field conditions are not yet clear. The effects of different nitrogen application modes on the yield of maize, As well as the influence of the deep nitrate nitrogen in soil and the agronomic efficiency of nitrogen fertilizer are of great significance to improve the efficiency of nitrogen fertilizer use and reduce the greenhouse gas emissions from agricultural sources. 【Method】 The experiment was carried out from April 2013 to September 2014 at the agro-ecological experimental station of Changwu Loess Plateau, Chinese Academy of Sciences. The tested plant was spring corn with the varieties of Xiangyu 335 and semi-plastic film planting. In this experiment, four treatments were conducted: Con, N, and Opt + DCD, N0, and soil samples and nitrous oxide Gas, the contents of mineral nitrogen and nitrous oxide in soil were measured by flow analyzer and gas chromatograph. The variance analysis of yield and each index of different treatments was done by SAS software. 【Result】 Both Opt and Opt + DCD significantly affect N 2 O 3 emission and nitrate residual while maintaining the yield. The peak value of nitrate treated by Opt decreased by 13.7%, while that of Opt + DCD reduced the peak of nitrate by 19.0%. Second, the mode of nitrogen application also affected the appearance time of nitrate nitrogen peak: Con (190.1 mg / kg) appeared first, followed by Opt (164.0 mg / kg) and Opt + DCD (132.9 mg / kg). Opt significantly reduced nitrous oxide emissions by 29.4%, while adding DCD based on Opt further reduced nitrous oxide emissions by 28.1%. Nitrate nitrogen and nitrous oxide emissions fluctuated with rainfall during the rainy season. Although Opt reduced the ammonium nitrogen peak, the addition of DCD to Opt increased the ammonium nitrogen peak. The nitrate nitrogen residuals of 0-100 cm and 100-200 cm soil profiles in the four nitrogen application modes ranged from 33.5 to 148.9 and 24.8 to 92.8 kg / hm2, with the average values of 78.5 and 56.4 kg / hm2, respectively. Compared with Con, the residuals of nitrate nitrogen in Opt and Opt + DCD decreased 48.0%, 59.0% and 29.4%, respectively, to 57.5% . There was no significant difference in nitrate nitrogen between Opt and Opt + DCD (P> 0.05). 【Conclusion】 Different nitrogen application modes have a significant effect on the dynamic changes of corn yield, mineral N and N2O and agronomic efficiency of nitrogen fertilizer. However, while the nitrogen application rate is reduced by 20%, Opt and Opt + DCD not only did not significantly reduce the yield of corn , Further reducing the residual nitrate nitrogen in agricultural soil profile and the emission of greenhouse gas from agricultural sources. Therefore, adding DCD in the rainfed farming area of the Loess Plateau is a scientific and effective way of fertilization management.