不同氮钾水平及氮形态差异对土壤氨挥发和氧化亚氮排放的影响

Effects of different nitrogen and potassium levels and nitrogen forms on soil ammonia volatilization and nitrous oxide emissions

研究不同氮钾用量下土壤氨(NH3)挥发和氧化亚氮(N2O)排放,为确定氮钾肥合理施用和大气环境保护提供理论依据。盆栽实验共9个处理:N0K0、(NO^-3-N)50K35、(NO^-3-N)50K80、(NO^-3-N)100K35、(NO^-3-N)100K80、(NH^+4-N)50K35、(NH^+4-N)50K80、(NH^+4-N)100K35、(NH^+4-N)100K80。分别采用静态箱法和通气法采集N2O和NH3。氮肥显著增大了N2O的排放通量和累积排放量以及NH3的挥发速率和累积排放量。N2O的平均排放通量和累积排放量从不施肥处理的15.8μg·m^-2·h-1和0.17 mg·kg^-1增加到氮肥用量100 mg·kg^-1时的45.6μg·m^-2·h-1和0.57 mg·kg^-1。NH3挥发速率和累积排放量在氮肥用量为100 mg·kg^-1时达到最大,分别为1.5 kg·hm^-2·d^-1和4.18 mg·kg^-1。铵态氮为氮源的各处理N2O排放通量和累积排放量以及NH3挥发速率和累积排放量均高于以硝态氮为氮源的各处理。钾肥显著增大了NH3挥发速率和累积排放量,但在低氮水平下,钾肥显著降低N2O排放通量和累积排放量。化学氮肥施用量的增加是NH3挥发和N2O排放增加的主要因素,与硝态氮肥相比,铵态氮肥更易于NH3和N2O的排放。增施钾肥显著增大土壤NH3挥发速率和排放量,但降低了土壤N2O的排放通量,显著减少了整个生长季节N2O的累积排放量。

Ammonia(NH3)volatilization and nitrous oxide(N2O)emissions in soils under different nitrogen(N)and potassium(K)levels were investigated, in order to provide data and a theoretical basis for the rational application of N and K fertilizers, and for atmospheric environmental protection. A pot experiment was carried out, which included 9 treatments:N0K0,(NO^-3-N)50K35,(NO^-3-N)50K80,(NO^-3-N)100K35,(NO^-3-N)100K80,(NH^+4-N)50K35,(NH^+4-N)50K80,(NH^+4-N)100K35, and(NH^+4-N)100K80. N2O and NH3 were collected by the static chamber method and aeration method, respectively. N fertilizer significantly increased the N2O flux and cumulative emissions, as well as the NH3 volatilization rate and cumulative emissions. The average N2O flux and cumulative emissions increased from 15.8 μg·m^-2·h-1 and 0.17 mg·kg^-1 without fertilization to 45.6 μg·m^-2·h-1 and 0.57 mg·kg^-1 with N fertilizer rates of 100 mg·kg^-1. The volatilization rate and cumulative emissions of NH3 also reached the maxima when the amount of N fertilizer was 100 mg·kg^-1;the corresponding values were 1.5 kg·hm^-2·d^-1 and 4.18 mg·kg^-1. Treatments with ammonium as a N source had higher N2O fluxes and cumulative emissions, and NH3 volatilization rates and cumulative emissions, compared to the treatment with nitrate as the N source. K fertilizer significantly increased NH3 volatilization rates and cumulative emissions. Under low N levels, K fertilizer significantly reduced N2O fluxes and cumulative emissions. Increase of the chemical N fertilizer application rate is the main factor in the increase in NH3 volatilization and N2O emissions. Compared with nitrate N fertilizer, ammonium N fertilizer promotes NH3 and N2O emissions. Increasing the application of K fertilizer significantly increases the NH3 volatilization rate and cumulative emissions, but significantly reduces the N2O flux and cumulative emissions throughout the growing season.