花生壳生物炭对潮土和红壤理化性质和温室气体排放的影响

为探讨花生壳生物炭用于农田土壤改良的效果,采用盆栽试验,结合静态箱-气相色谱法研究了施用不同剂量(0、0.5%、1%、2%、4%)花生壳生物炭对红壤和潮土的理化性质及温室气体排放变化特征的影响。结果表明,施用生物炭对潮土温室气体排放的影响较大,且两种土壤表现出不同的排放特征。总体上,潮土N_2O累积排放量显著高于红壤,与单施氮肥处理相比,随生物炭添加量的增加,潮土N_2O累积排放量显著降低,降幅达6.5%~26.6%;红壤N_2O累积排放量则随生物炭添加量的增加呈上升趋势,与单施氮肥处理相比,红壤N_2O累积排放量增幅为14.7%~54.3%。与对照相比,施用生物炭显著增加潮土CO_2排放,其累积排放量增幅最大为25.9%;而对红壤CO_2累积排放量则没有显著影响。此外,在施用不同剂量生物炭处理下,两种土壤CH_4排放无规律性变化,CH_4排放累积量总体在0左右。与空白对照和单施氮肥处理相比,随生物炭添加量的增加,两种土壤的固碳量显著增加,潮土增加了57.1%~78.7%,红壤增加了11.2%~59.9%;同时随生物炭的施用,潮土温室气体排放强度显著提高68.0%~76.8%,而生物炭添加量对红壤的温室气体排放强度无显著影响。分析认为,对潮土施用生物炭通过改变土壤容重、有机碳、无机氮等养分含量,显著提高温室气体排放强度,抑制供试作物生长,增强其净综合温室效应;而对红壤添加生物炭则可促进作物生长,其温室气体排放强度无显著增加,提升土壤固碳量,具有较好的生态效应。

Effects of peanut shell biochar on physico-chemical properties and greenhouse gas emission in fluvo-aquic soil and red soil

The present study evaluated the effects of different concentrations of biochar(0%, 0.5%, 1%, 2%, and 4%) on the physico-chemical properties of red and fluvo-aquic soils, and the emission of greenhouse gases(GHGs). A pot experiment was set with different treatments, and the GHGs emitted were measured by static chamber-gas chromatographic techniques. The results showed that biochar application had significant effects on the greenhouse gas emission, and the two soils showed different gas emission characteristics. In general, the cumulative emission of N₂O from the fluvo-aquic soil was significantly higher than that in the red soil. Compared with the single application of nitrogen fertilizer treatment(MN), biochar application led to a 6.5%~26.6% decrease in cumulative emission of N₂O from the fluvo-aquic soil. In contrast, the cumulative emission of N₂O from the red soil increased with increase in the concentration of biochar. It increased from 14.7% to 54.3% when compared with the single application of nitrogen fertilizer treatment(RN). The 0.5% biochar treatment significantly increased CO₂ emission from the fluvo-aquic soil; it increased the cumulative emission by 25.9%. However, the 0.5% biochar treatment did not significantly affect the cumulative emission of CO₂ from the red soil. In addition, the CH₄ emission flux of the two soils changed irregularly under different treatments, and the cumulative emission of CH₄ was negligible. A comparison of treatments MCK(blank control for fluvo-aquic soil), RCK(blank control for red soil), MN, and RN(without biochar application) revealed that the carbon sequestration of both the soils increased significantly with increase in the concentration of biochar. In the fluvo-aquic soil, the increase was by 57.1%~78.7%, while in the red soil, it was 11.2%~59.9%. The biochar application enhanced greenhouse gas emission intensity(GHGI) of the fluvo-aquic soil by 68.0%~76.8%, while it had no significant effect on the GHGI of the red soil. The results suggested that biochar application could significantly increase the GHGI and inhibit the growth of crops in the fluvo-aquic soil. The increase in GHGI was owing to change in the soil bulk density and content of organic carbon, inorganic nitrogen, and other nutrients. Furthermore, biochar application to red soil had better ecological effects. It could promote the growth of crops(as evidenced by the fact that its GHGI did not increase significantly) and enhance soil carbon sequestration.