等氮量下不同分施次数对燥红壤N_2O排放的影响

Effects of Different Nitrogen Application Times on N_2O Emission in Dry Red Soil

通过室内培养试验研究等氮量下不同施肥次数对N_2O排放的影响。试验设一次性施氮(S1,将200 mg/kg氮肥一次性施入土壤),二次分施(S2,将200 mg/kg氮肥分两次平均施入土壤),三次分施(S3,将200 mg/kg氮肥分80、60、60 mg/kg 3次施入土壤)和空白(CK,不施肥)4个处理。培养在65%田间持水量,30℃恒温箱中进行。结果表明,氮肥施入显著促进土壤N_2O排放;等施氮量下,不同分施次数使土壤pH呈显著性差异,而土壤pH的差异又影响了土壤N_2O累积排放量;分施次数越多,土壤酸化程度越强,N_2O累积排放量越少。因此,在等施氮量下,要充分考虑土壤酸化、N_2O排放、NO–3-N积累以及施肥成本等,确定合理分施次数。

An indoor incubation under 30 ℃ and 65% water holding capacity was conducted to study how different split applications, in the circumstances of equal nitrogen amount, respectively affected N2O emission. Four treatments were designed, including one-time application （S1, 200 mg/kg nitrogen fertilizer was applied to the soil at one time）, two separate applications （S2, 200 mg/kg nitrogen fertilizer equally distributed into the soil）, three separate applications （S3, 200 mg/kg nitrogen fertilizer was divided into three different times： 80, 60 and 60 mg/kg）, and control （CK, no fertilization）. The results showed that the application of nitrogen fertilizer significantly promoted N2O emission in soil. Under the same nitrogen application rate, different application times significantly resulted in differences of soil pH, which would further affect the N2O accumulation emission. The more times of applications, the greater the degree of soil acidification, so the less cumulated amount of N2O emissions. Therefore, under the condition of the same amount of nitrogen, soil acidification, N2O emissions, nitrate nitrogen accumulation and fertilizer costs should be comprehensively considered in determining the reasonable split applications.