控释氮肥减量施用对春玉米土壤N2O排放和氨挥发的影响

在大田条件下采用密闭室间歇通气法和密闭式静态箱法研究了控释氮肥不同施氮水平对春玉米土壤N_2O排放和氨挥发的影响。结果表明:与T2(普通尿素)处理相比,控释氮肥处理(T3~T6)N_2O排放通量变化趋势平稳,无明显的峰值;从累积排放量上看,与T2处理相比,T3(240 kg N·hm~(-2))、T4(216 kg N·hm~(-2))、T5(192 kg N·hm~(-2))、T6(168 kg N·hm~(-2))处理N_2O排放量分别减少27.80%、33.66%、45.85%、55.12%,但T2与T3、T4处理之间差异不显著(P0.05),与T5、T6处理之间差异显著(P0.05);各控释氮肥处理间差异均不显著(P0.05),与施肥量呈极显著的指数函数关系(P0.01)。T2处理氨挥发速率在施肥后的2~4 d内出现峰值,而各控释氮肥处理在基肥、苗肥、穗肥施用后,分别在第9、6、1~2 d出现峰值;与T2处理相比,T3、T4处理氨挥发量反而分别增加了8.02%和0.97%,但差异均不显著(P0.05),T5、T6处理氨挥发量分别减少了8.86%(P0.05)和16.65%(P0.05);各控释氮肥处理间,与T3相比,T4、T5、T6处理氨挥发量分别减少了6.53%(P0.05)、15.62%(P0.05)和22.84%(P0.01),且氨挥发量与施氮量呈极显著线性关系(P0.01)。从产量上看,各施氮肥处理玉米产量均显著高于不施氮肥处理,但各施氮肥处理间差异不显著(P0.05)。综合产量和N_2O排放、氨挥发考虑,控释氮肥的合理减氮施用能够发挥更大的环境效益。

Effects of reduced CRNF applications on N2O emissions and ammonia volatilization in spring maize soil

Effects of controlled-release nitrogen fertilizer(CRNF) applied at different rates on N₂O emissions and ammonia volatilization from spring maize soil were studied using both closed chamber with intermittent aeration and closed static chamber. The treatments were no-nitrogen control(T1), common urea at normal rate(240 kg·hm^-2, T2); controlled-release urea at normal rate(240 kg·hm^-2,T3); controlled-release urea at 10% less(216 kg·hm^-2,T4); controlled-release urea at 20% less(192 kg·hm^-2,T5); and controlled-release urea at 30% less(168 kg·hm^-2,T6). Results showed that the dynamics of N₂O emissions from the treatments T3~T6 were relatively stable, with no obvious peaks, compared with the treatment T2. Cumulative N₂O emissions were 27.80%, 33.66%, 45.85%, and 55.12% lower in T3, T4, T5, and T6 than in T2, respectively. The N₂O emissions in T3 and T4 were not significantly different from that in T2, whereas there were significant differences in N₂O emissions between T2 and T5 and T6. However, no significant differences were found among CRNF treatments(T3~T6). The N₂O emission had an exponential relationship with N application rate(P<0.01). The peak of ammonia volatilization in T2 emerged on the 2nd~4th day of fertilization, but on the 9th, 6th, and 1st~2nd day of base fertilization, seedling fertilization and panicle fertilization, respectively, in treatments T3~T6. The ammonia volatilization in T3 and T4 was 8.02% and 0.97% higher than that in T2, respectively, with no significant differences between them. However, the ammonia volatilization in T5 and T6 were 8.86% and 16.65% lower than that in T2. A linear relationship between ammonia volatilization and N application was found(P<0.01). The yields of maize in all treatments with N applications were significantly higher than in the control, but no significant differences were found among nitrogen-applied treatments. The present results suggest that appropriate reduction of CRNF would alleviate N₂O emissions and ammonia volatilization while maintaining maize yields.