施氮量对库尔勒香梨园氨挥发和氧化亚氮排放的影响

为了解库尔勒香梨园土壤氮素气态损失，采用密闭式集气法和静态箱气相色谱法对不同氮肥用量下的土壤氨挥发和氧化亚氮排放进行研究，并设置了5个处理：不施肥（N₀P₀K₀）、不施氮肥（N₀PK）、施氮150 kg·hm^-2（N₁PK）、施氮300 kg·hm^-2（N₂PK）、施氮450 kg·hm^-2（N₃PK）。结果表明：氨挥发速率和氧化亚氮排放通量均在施基肥和施追肥后第4天出现峰值和次峰值，且氨挥发速率和氧化亚氮排放通量均随着施氮量的增加而增大；各处理氨挥发累积量达到27.886～44.416 kg·hm^-2·a^-1，施氮处理氨挥发净损失量达到6.726～16.197 kg·hm^-2·a^-1，各处理氧化亚氮累积量达到341.616～531.960 g·hm^-2·a^-1，施氮处理氧化亚氮净损失量达到90.452～185.412 g·hm^-2·a^-1，氨挥发累积量和净损失量与氧化亚氮累积量和净损失量均随着施氮量的增加而增加；施氮处理氨挥发净损失率为2.720%～4.480%，氧化亚氮净损失率为0.038%～0.060%，氨挥发和氧化亚氮净损失率随着施氮量的增加均表现为先减小再增大；施用氮肥能显著增加0～20 cm和20～40 cm土层中铵态氮和硝态氮含量；相关分析表明，氨挥发速率和氧化亚氮排放通量与施氮量和土壤温度呈极显著正相关关系；N₂PK处理的库尔勒香梨产量最高，达到6 213.5 kg·hm^-2，且氨挥发净损失率和氧化亚氮净损失率均最小，为2.720%和0.038%。从库尔勒香梨园土壤氮素气态损失和生产角度看，纯氮用量为300 kg·hm^-2时最佳。

Effect of nitrogen application rate on ammonia volatilization and nitrous oxide emission in Korla fragrant pear orchard

To understand the nitrogen (N) loss of soil N in the Korla fragrant pear orchard, in this study, the methods of closed gas gathering and the static box-gas chromatography were used to study the soil ammonia volatilization and nitrous oxide emission under different N fertilizer rates. Five treatments were set including no fertilization (N₀P₀K₀), no N application (N₀PK), N application 150 kg·hm^-2 (N₁PK), N application 300 kg·hm^-2 (N₂PK), N application 450 kg·hm^-2 (N₃PK). The results showed that both ammonia volatilization rate and nitrous oxide emission flux peaked on the 4th day after application of base fertilizer and top dressing, the ammonia volatilization rate and nitrous oxide emission flux increased with increasing the N application rate. The cumulative amount of ammonia volatilization among the different treatments reached 27.886~44.416 kg·hm^-2·a^-1, the net loss of ammonia volatilization with N application treatments reached 6.726~16.197 kg·hm^-2·a^-1, the cumulative amount of nitrous oxide among the different treatments reached 341.616~531.960 g·hm^-2·a^-1, the net loss of nitrous oxide with N application treatments reached 90.452~185.412 g·hm^-2·a^-1, the accumulation of ammonia volatilization and the net loss, the cumulative amount of nitrous oxide and the net loss all increased with increasing the nitrogen application rate, the net loss rate of ammonia volatilization with nitrogen application treatments was 2.720%~4.480%, the net loss rate of nitrous oxide was 0.038%~0.060%, the net loss rate of ammonia volatilization and nitrous oxide both showed a tendency to decrease first and increase later with increasing the amount of N applied. Application of N fertilizer could significantly increase the content of ammonium N and nitrate N in 0~20 cm and 20~40 cm soil layers. Correlation analysis showed that ammonia volatilization rate and nitrous oxide emission flux were significantly positively correlated with N application rate and soil temperature. The yield of Korla fragrant pear treated with N₂PK reached 6 213.5 kg·hm^-2, which was the highest. But, the net loss rate of ammonia volatilization and nitrous oxide were the smallest, which were 2.720% and 0.038%, respectively. From the perspective of N loss in the soil and production in Korla fragrant pear orchard, the optimum amount of pure N was 300 kg·hm^-2.