水热条件对黄土性小麦田N_2O排放特征的影响

Effects of Water and Temperature on N2O Emission from Loess Soil Grown Wheat

以西北地区黄土性冬小麦田为研究对象,观察分析了不同年份小麦在不同生长期、不同水热条件下,各耕层土壤N2O排放的特征。结果表明,降雨和气温与N_2O排放通量存在相关性,二者的共同作用引起年际间土壤N_2O排放量的差异,而温度效应更大。小麦生长季节大田土壤N_2O排放通量的变化与土壤10￣20cm深处温度有显著线性相关,但在孕穗期至开花期,N_2O排放通量与土壤温度相关性不明显,其排放通量的升高主要受控于作物根系活动。在适宜土壤含水量范围内,土壤水分增加对土壤N_2O排放具有正效应,但与耕层水分相关性未达显著。值得注意的是在干旱缺水条件下土壤N2O排放通量与NH_4^+-N含量大小间呈极显著相关。

N2O emission from the loess soil during different growth periods of wheat was studied in Northwest China. The effects of soil water content, temperature and soil depth on N20 emission from a wheat field were investigated. The results showed that both rainfall and tempera- ture were related to N2O emission, but temperature had a greater effect. The interaction between rainfall and temperature led to a difference in N2O flux between 2001 and 2002. Water content and temperature had a significant influence on N2O emission from the winter wheat soil system. During periods of wheat growth, N2O emission rate showed significant linear correlation with temperature in the soil layers between 10 and 20 cm, but did not with water content. Within the normal range of soil water content （10%-25%）, N2O emission increased with soil water ＋ content. N2O flux rate was significantly related to NH4-N content when soil water content was lower than 15%. At the beginning or later periods of growth, N2O emission were advanced with the increase of soil temperature. However, the trend was opposite during the booting stage to flowering stage due to the activity of wheat roots in the soil.