滴灌追氮管理对宿根蔗田土壤氮组分及N2O排放的影响

【目的】研究滴灌追氮管理对宿根蔗田土壤氮组分和N₂O排放的影响,揭示影响土壤N₂O通量的土壤因子。【方法】以二代宿根蔗Saccharum officinarum为研究对象,在移动防雨棚内进行2个滴灌灌水量[田间持水量的70%～80%(W0.8)和田间持水量的80%～90%(W0.9)]及3种滴灌追氮比例(等氮量250 kg·hm^-2,其中,N0为用作追肥的氮肥全部施用到土壤中,N5为50%土施追氮、50%用滴灌系统施用,N7为30%土施追氮、70%滴灌追氮)的田间试验。在甘蔗生长的各个时期测定蔗田土壤N₂O通量、pH和氮组分含量,并分析土壤N₂O通量与土壤pH和氮组分含量的关系。【结果】土壤N₂O通量在施用氮肥和灌水后2 d较高,其中,分蘖后期和成熟期W0.9N5处理的土壤N₂O通量显著低于其他处理。W0.9条件下,分蘖后期N5处理的土壤N₂O累积排放量分别比N0和N7低47.3%和11.8%,伸长后期N5处理的...

Effect of nitrogen fertigation management on soil nitrogen fractions and N2O emissions from ratoon sugarcane fields

Objective To study the effects of drip irrigation nitrogen (N) chasing management on soil N fraction and N₂O emission in host cane fields, and reveal the soil factors affecting soil N₂O fluxes.Method Two water drip irrigation levels of W0.8 (70%?80% of field water holding capacity) and W0.9 (80%?90% of field water holding capacity) and three drip irrigation N chasing ratios (250 kg·hm^?2 of equal N) were carried out in a mobile rain-proof shelter with the second generation host cane (Saccharum officinarum) as the research object. N0 was all the N fertilizer applied to the soil (referred to as soil-applied N); N5 was 50% soil-applied N and 50% applied by drip irrigation system (referred to as drip-applied N); N7 was 30% soil-applied N and 70% drip-applied N in the field trials. Soil N₂O flux, pH and nitrogen fraction content were measured at each period of sugarcane growth, and the relationship between soil N₂O flux and soil pH/nitrogen fraction content was analyzed.Result Soil N₂O flux was higher after two days of applying N fertilizer and water irrigation, and the soil N₂O flux of W0.9N5 was significantly lower than other treatments at the late tillering stage and maturity stage. Under W0.9, the cumulative soil N₂O emissions in N5 at the late tillering stage were 47.3% and 11.8% lower than those of N0 and N7, and 21.5% lower than those of N7 at the late elongation stage. Soil nitrate N content showed W0.9 > W0.8 for the same drip irrigation N rate, and increased with the increase of water irrigation. At the early elongation and maturity stage, the soil ammonium N content of N5 under W0.8 was 56.4% and 71.8% higher than those of N0, was 68.5% and 160.3% higher than those of N7. At the late tillering stage, soil microbial biomass nitrogen showed N5 > N7 > N0 under the same water drip irrigation level, and soil microbial biomass nitrogen of N5 was 120.0% and 100% higher than N0 under both water irrigation rates, respectively. There was a positive correlation between soil N₂O flux and ammonium N content (r=0.313) and a negative correlation with nitrate N (r=?0.391).Conclusion W0.9N5 treatment can reduce soil N₂O emissions, and soil ammonium N content and nitrate N content affect soil N₂O flux, i.e., higher soil ammonium N content is associated with higher soil N₂O flux, while higher soil nitrate N content is associated with lower soil N₂O flux.