旱地土壤施用生物质炭的后效应——水分条件对土壤有机碳矿化的影响

农田施用生物质炭作为农田土壤固碳减排技术的重要措施已受到广泛关注。本研究选择一次性大量施入生物质炭3年后且长期种植玉米的旱地土壤为研究对象,通过室内培养试验,研究了不同水分条件下的有机碳稳定性的变化,结果表明:一级动力学方程较好地描述了土壤有机碳的矿化动态,总体看来旱地土壤有机碳的矿化强度随土壤含水量的增加而增大,在25%WHC(持水量,water holding capacity)、50%WHC和75%WHC水分条件下,与C0(无生物质炭)相比,C20(生物质炭20 t/hm2)、C40(生物质炭40 t/hm2)处理下,有机碳的矿化强度分别降低了28.57%~42.86%(25%WHC)、22.22%~33.33%(50%WHC)、15.00%~30.00%(75%WHC),不同处理下土壤的微生物商和微生物代谢熵对水分的响应存在明显差异,与对照相比,生物质炭施用下微生物量相对稳定,且稳定程度与生物质炭用量有关。因此,旱地土壤施用生物质炭具有保持微生物量稳定且降低土壤有机碳矿化与CO2释放的作用,这对于农田土壤有机碳的固持增汇具有重要意义。

Effects of Biochar Application History on Soil: Effect of Moisture Regime on Dynamics of Soil Organic Carbon Mineralization

Biochar application has been suggested as an effective means in abating climate change by sequestering carbon. In this study, a 3-year field experiment was conducted to investigate the effects of biochars on soil organic carbon (SOC) cycling under laboratory incubation under different water conditions change. The results indicated that the dynamics of SOC minerali-zation preferably followed the first-order kinetics. Soil moisture affected SOC mineralization significantly. Under 25%WHC (water holding capacity), 50%WHC and 75%WHC moisture conditions, compared with C0 (no biochar), the intensity of mineralization of SOC under C20 (biochar, 20 t/hm2) and C40 (biochar, 40 t/hm2) decreased by 28.57% – 42.86% (25%WHC), 22.22% – 33.33% (50%WHC) and 15.00% – 30.00% (75%WHC), respectively. There were significant differences in responses of microbial biomass carbon, soil organic carbon and metabolic quotient to the water regimes with Biochar addition. Biochar could keep the stability of the microbial biomass carbon and reduce SOC mineralization under low moisture content. Therefore, the results indicated that BC has the important significance for soil carbon sequestrating and maintaining the stability of soil organic carbon in agricultural soil.