陇东旱塬麦黑豆-冬小麦轮作条件下施氮水平对土壤N2O和CH4排放的影响

Effects of Black Soybean-winter Wheat Rotation and Nitrogen Application on Soil N2O and CH4 Emission of Longdong Dryland in Gansu

为给我国旱地低碳农业可持续发展提供科学依据,2018—2020年在陇东黄土高原雨养区冬小麦田设置夏闲期种植绿肥和不同施氮量田间试验,通过测定土壤N_(2)O和CH_(4)排放通量,计算N_(2)O和CH_(4)累积排放量等指标,分析不同处理对土壤N_(2)O和CH_(4)排放通量和累积排放量的影响。结果表明,在2个轮作周期内,不同处理的N_(2)O排放峰主要出现在冬小麦播种施肥后,峰值范围平均11.24~31.85μg N_(2)O-N/(m^(2)·h)。土壤CH_(4)排放无明显峰谷变化趋势,而围绕着零值上下波动,变化范围-46.8~24.5μg CH_(4)-C/(m^(2)·h)。与休闲-冬小麦处理相比,麦黑豆-冬小麦轮作处理在绿肥填闲期和冬小麦生长期土壤N_(2)O累积排放分别显著增加了26.8%~44.2%和6.2%~52.3%,土壤CH_(4)累积吸收分别显著减少了7.9%~76.3%和4.0%~28.4%。可见,豆科绿肥填闲种植可增加土壤N_(2)O排放,减少土壤CH_(4)的吸收。

In order to provide scientific basis for the sustainable development of low carbon agriculture in dryland area of China,a field experiment of green manure and different nitrogen rates in the winter wheat field in summer fallow period in the Longdong dryland of Gansu Province was conducted from 2018 to 2020.Soil N_(2)O and CH_(4)emission fluxes and cumulative emissions were measured.Effects of different treatments on soil N_(2)O and CH_(4)emission fluxes and cumulative emissions were analyzed.The results showed that during 2 rotation periods,the peaks of N_(2)O emission fluxes mainly occurred after sowing and fertilization of winter wheat,and ranged from 11.24 to 31.85μg N_(2)O-N/(m^(2)·h).Soil CH_(4)emission fluxes didn't show a peak-valley variation trend but fluctuated around the zero value,and ranged from-46.8 to 24.5μg CH_(4)-C/(m^(2)·h).Compared with the fallow-winter wheat treatment,soil N_(2)O cumulative emissions in black soybean-winter wheat rotation were significantly increased by 26.8%to 44.2%and 6.2%to 52.3%for the green manure planting period and the winter wheat growing season,respectively,and soil CH_(4)cumulative absorption were significantly decreased by 7.9%to 76.3%and 4.0%to 8.4%for those two periods above,respectively.It showed that planting leguminous green manure in summer fallow period could increase soil N_(2)O emission and reduce soil CH_(4)absorption.