控释氮肥配施对不同覆盖旱作农田CO2排放的影响

为探讨黄土高原旱作不同覆盖下控释氮肥配施对春玉米农田二氧化碳(CO_2)排放的影响,2016—2018年在长武农业生态试验站进行了田间定位试验,采用静态暗箱-气相色谱法研究了地膜覆盖(FM)与秸秆覆盖(SM)条件下不施氮肥(N0)、100%普通尿素(N1)、树脂尿素和普通尿素比例1∶2(N2)三种施氮处理农田CO_2排放的动态变化特征。结果表明:旱作春玉米农田土壤CO_2排放通量的变化幅度在3.62～248.45 mg CO_2-C·m~(-2)·h~(-1),且呈先增加后降低的趋势。不同处理农田CO_2排放通量与0 cm和10cm土壤温度均呈极显著正相关。与不施肥相比,施用氮肥均显著增加农田CO_2排放通量和累积排放量。与施普通尿素相比,控释氮肥配施显著减少生长季和全年CO_2累积排放量达7.3%～10.12%。施氮处理CO_2排放通量与NO_3~--N和NH_4~+-N呈显著正相关。在相同施氮条件下,秸秆覆盖处理CO_2累积排放量均高于地膜覆盖处理。上述结果说明,控释氮肥配施处理有利于减少旱作不同覆盖春玉米农田CO_2排放。

Effects of controlled-release urea on CO2 emission from dry farmland under different mulching patterns

In order to investigate the effects of controlled-release urea(CRU)on carbon dioxide(CO₂)emission from spring maize farmland under different mulching patterns on the Loess Plateau, field experiments were conducted at Changwu Agricultural and Ecological Experimental Station from 2016 to 2018. The experimental treatments included no nitrogen fertilizer application(N0), application of 100% urea at a rate of 225 kg N·hm-(2 N1), and CRU combined with conventional urea application ratio of 1:2 and rate of 225 kg N·hm^-2(N2) under plastic film mulching(FM)and straw mulching(SM). The results showed that CO₂ emission in dry spring maize farmland increased first and then decreased, ranging from 3.62 to 248.45 mg CO₂-C·m^-2·h^-1. There was a significant and positive correlation between CO₂ emission rate and soil temperature for 0~10 cm soil depths under different treatments. Compared with N0, nitrogen fertilizer application significantly increased the CO₂ emission rate and cumulative CO₂ emission. The cumulative CO₂ emission during the growing season of maize and the whole year for the treatment N2 was significantly lower, by 7.3%~10.12%, relative to N1. There was a significant positive correlation between CO₂ emission rate and nitrate and ammonium concentrations. Under the same nitrogen application rate, cumulative CO₂ emission under straw mulching was higher compared to that under plastic film mulching. These results indicate that CRU and conventional urea application ratio of 1:2 is beneficial for reducing CO₂ emission from spring maize fields under different mulching patterns in dry farmland.