采用静态暗箱-气相色谱法对紫色土坡耕地常规施肥处理（CL）、坡耕地不施肥处理（CL-CK）和退耕15、30年的桤柏混交林地（FL15、FL30）的土壤N2O排放通量进行为期1年的观测，同时测定土壤温度、土壤湿度、土壤无机氮含量等。结果表明，观测期内CL、CL-CK、FL15与FL30的N2O平均释放速率分别是25.6、6.60、1.20、4.35μg N2O-N·m-2·h-1，CL小麦季N2O平均释放速率是18.0μg N2O-N·m-2·h-1，玉米季35.2μg N2O-N·m-2·h-1，CL土壤N2O排放速率显著高于CL-CK、FL15和FL30（P＜0.01），且CL-CK高于FL15、FL30（P＜0.01），FL30高于FL15（P＜0.01）。CL、CL-CK、FL15和FL30全年的N2O排放量分别为1.01、0.400、0.050、0.310 kg N2O-N· hm-2。比较CL以及CL-CK的N2O排放总量，停止施氮的措施对土壤N2O排放的减排潜力达到0.610 kg N2O-N·hm-2。与CL-CK相比，FL15、FL30土壤N2O释放量分别减少0.350、0.090 kg N2O-N·hm-2，主要原因是退耕后土壤碳氮比升高，土壤无机养分、温度以及湿度等发生变化。
Effect of Returning Cropland to Forestland on N2O Emissions from Sloping Purple Soil
Cropland is a large source of global N2O emissions, while forestland emits much less N2O. Thus, returning cropland to forestland would help reduce global N2O emissions. Here static chamber-GC technique was used to compare soil N2O emission fluxes from sloping cropland(CL)and forestland returned from cropland for 15 and 30 years. Soil temperature, moisture, nitrate(NO-3- N)and ammonia (NH+4-N)nitrogen content in the soils were also recorded for one year. Results showed that average fluxes of soil N2O from CL, CL-CK (CL-Check test), FL15 and FL30(15 and 30 years old forest)were 25.6, 6.60, 1.20, and 4.35μg N2O-N·m-2·h-1, respectively, with signifi-cantly higher N2O emissions from CL than from CL-CK, FL15 and FL30(P<0.01). The N2O emissions from FL30 were also significantly higher than that from FL15(P<0.01). Annual cumulative N2O emissions from CL, CL-CK, FL15 and FL30 were respectively 1.01, 0.400, 0.050, and 0.310 kg N2O-N·hm-2. The potential of N2O mitigation by nitrogen fertilizer reduction was as high as 0.620 kg N2O-N·hm-2. Compared with CL-CK, FL15 and FL30 reduced N2O emissions by 0.350 and 0.090 kg N2O-N·hm-2, respectively, may due to increases in soil carbon to nitrogen ratios and changes in soil properties.
purple soilalder and cypress mixed forest landsloping croplandreturning cropland to forestlandN2O
国家科技期刊平台
NSTL
万方数据
维普
