施肥对板栗林地土壤N2O通量动态变化的影响

2011年6月-2012年6月期间, 在浙江省临安市典型板栗林地进行施肥对土壤N₂O通量变化影响的试验研究。目的在于探明不同施肥处理下板栗林地土壤N₂O通量的动态变化规律,并探讨土壤N₂O通量和土壤环境因子之间的关系。试验设置4个处理:对照(不施肥)、无机肥、有机肥、有机无机混合肥。采用静态箱-气相色谱法测定了板栗林地土壤N₂O通量,并测定了土壤温度、水分、水溶性有机碳(WSOC)和微生物量碳(MBC)含量。结果表明:板栗林土壤N₂O通量呈显著季节性变化,最大值出现在夏季,最小值出现在冬季;而且,施肥处理显著提高土壤N₂O年均通量和年累积量;在整个试验期间,无机肥、有机肥和有机无机混合肥处理下土壤N₂O的排放系数分别达到0.96%、1.45%和1.29%。此外,施肥也显著增加了土壤WSOC和MBC的含量(P < 0.05)。不同施肥处理条件下,土壤N₂O通量与土壤5 cm处温度、WSOC含量间均呈极显著正相关(P<0.01),但与MBC含量之间的相关性不显著。土壤N₂O排放与土壤含水量间除对照处理外均没有显著相关性。综上所述,施肥引起土壤WSOC含量的增加可能是施肥增加板栗林地土壤N₂O排放速率的主要原因之一。

Effect of fertilization on the dynamic of soil N2O fluxes in Chinese chestnut stands

Response of soil N₂O emissions to inorganic fertilizer and organic fertilizer in the typical Castanea mollissima was studied from June 2011 to June 2012 in Lin''an, Zhejiang Province. The objectives were to evaluate the response of the soil N₂O efflux to different fertilization and explore the relationships between the various environmental factors and N₂O efflux. Four treatments were applied in this study: Control (CK), inorganic fertilizer (IF), organic fertilizer (OF), and half organic plus half inorganic fertilizer (OIF). Soil N₂O emission were analyzed by static closed chamber-GC technique. Soil temperature, soil moisture, WSOC and MBC concentrations were determined as well. Our results showed that soil N₂O emission exhibited a strong seasonal pattern, the highest rates observed in summer season and the lowest in winter season. The mean annual soil N₂O flux and soil N₂O annual accumulative in IF were significantly higher than that in CK, but lower than that in OF and OIF treatments (P < 0.05). Soil N₂O emission factors of IF, OF, and OIF treatment were 0.96%, 1.45%, and 1.29%, respectively. Fertilization treatments significantly increased soil water-soluble organic carbon and microbial biomass carbon concentrations (P < 0.05). Soil N₂O emission rates had a significant positive correlation with soil temperature at 5 cm depth and WSOC concentration (P < 0.01), but had no significant correlation with soil MBC concentration in all treatments. However, soil N₂O emission did not correlate with soil moisture except in CK treatment. In conclusion, the increase of WSOC caused by fertilization was probably one of the important reasons for the increase in N₂O emission in the soil of Chinese chestnut stands induced by fertilization.