施肥对板栗林土壤活性碳库和温室气体排放的影响

Effect of fertilization on labile carbon pools and emissions of greenhouse gas in soils of Chinese chestnut stands

在浙江省临安市典型板栗林试验地,利用静态箱-气相色谱法测定了不同施肥条件下板栗林土壤CO2和N2O排放速率,同时测定了土壤水溶性有机碳(WSOC)和微生物量碳(MBC)含量。初步探讨了施肥对板栗林土壤活性碳库与温室气体排放速率的影响,以及土壤温室气体排放速率与活性碳库之间的关系。本试验设置不施肥(CK)、无机肥(IF)、有机肥(OF)和有机无机混合肥(OIF,1/2无机肥和1/2有机肥)4个施肥处理。结果表明,施肥1个月后,与不施肥(CK)处理相比,无机肥(IF)、有机肥(OF)和有机无机混合肥(OIF)处理下土壤CO2排放速率分别增加了87%、38%和61%,N2O排放速率分别增加了101%、67%和95%;而施肥6个月后,与CK处理相比,IF、OF和OIF处理下土壤CO2排放速率分别增加了51%、43%和64%,N2O排放速率分别增加了21%、29%和47%。同时,施肥显著增加板栗林土壤WSOC和MBC含量(P<0.05)。此外,土壤CO2和N2O排放速率与WSOC含量均呈显著正相关(P<0.05),而与MBC含量没有显著的相关性。因此,施肥引起板栗林地土壤WSOC含量增加可能是导致板栗林地土壤温室气体排放增加的重要原因之一。

Soil greenhouse gas （CO2 and N2O） emission rates were analyzed by the method of static closed chamber/GC technique, and soil labile organic carbon pools, including watersoluble organic carbon （WSOC） and microbial biomass carbon （MBC） concentrations, were determined as well in the typical Chinese chestnut （Castanea mollissima） stands of Lin’an, Zhejiang Province. There were four different fertilizer treatments, including no fertilizer （CK）, inorganic fertilizer （IF）, organic fertilizer （OF）, and half organic plus half inorganic fertilizer （OIF）. The objectives of this study were to investigate the effects on soil CO2 and N2O emission rates and soil labile organic carbon pools in different fertilization treatments and reveal the relationships between greenhouse gas emissions and soil labile carbon pools. The results show that the fertilization could significantly increase emissions of CO2 and N2O in Chinese chestnut stands （P〈 0.05）. Compared with the CK treatment, the CO2 emission rates in IF, OF, and OIF treatments are increased by 87%, 38%, and 61%, respectively, after one month of fertilization, and are increased by 51%, 43%, and 64%, respectively, after six months of fertilization. Meanwhile, the N2O emission rates in IF, OF, and OIF treatments are increased by 101%, 67% and 95%, respectively, after one month fertilization, and are increased by 21%, 29%, and 47%, respectively, after six months of fertilization. Additionally, the fertilization could significantly increase the WSOC and MBC concentrations （P〈 0.05）. The soil CO2 and N2O emission rates have significant positive correlations with soil WSOC concentrations （P〈 0.05）, but have no significant correlations with soil MBC concentrations. We suggest that increasing soil WSOC concentration by fertilization may contribute to increase soil greenhouse gas emission in Chinese chestnut stands.