免耕对土壤微生物量碳影响的Meta分析

为综合分析免耕(NT)对土壤微生物碳含量的影响程度,以常规耕作(CT)为对照,收集国内外关于免耕对土壤微生物碳研究已公开发表的41篇文献的田间试验数据162组,采用Meta数据整合分析方法,定量分析中国不同区域、气候类型和试验年限下,免耕对于中国农田土壤微生物碳含量的影响。结果表明,与常规耕作相比,免耕能显著提高土壤微生物碳的含量,免耕-常规耕作(NT-CT)的加权均数差值(WMD)为49.29 mg·kg^-1;免耕对土壤中微生物碳含量的影响存在区域差异性,西南地区WMD最大,湿润区(年降雨量>800 mm)免耕对土壤微生物碳含量的正效应最显著;年均温度10~15℃和年均温度>15℃时,免耕土壤中微生物碳含量显著高于常规耕作,且随着温度的升高而增加;免耕年限能够显著影响土壤微生物碳含量,以长期免耕(免耕年限≥8 a)效果最佳。综上,免耕对土壤微生物碳的增加效应存在区域特征,以西南地区最高,随着区域水热条件、免耕年限的不同有所差异,免耕措施的采用应该根据区域特点因地制宜。本研究结果为免耕的区域性合理利用提供了参考依据。

Meta-analysis to Assess Impact of No-tillage on Soil Microbial Biomass Carbon

To assess the effect of no-tillage (NT) on soil microbial biomass carbon,a Meta-analysis was conducted using a total of 162 data pairs from 41 published literatures with focusing on the croplandof China. The weighted mean difference(WMD) were calculated by analyzing mean content of soil microbial biomass carbonfrom no-tillage and conventional tillage among different agricultural areas, climate types, and no-tillage years. The results showed that the average WMD between no-tillage and conventional tillage was 49.29 mg·kg^-1, indicating that no-tillage treatment had significant positive effect on soil microbial biomass carbon. The WMD in southwest China and humid zone (annual precipitation >800mm) were obviously higher than other regions and climate zones. Besides,the WMD increased significantly with the annual average temperature and areas with annual temperature of more than 10℃ had higher soil microbial biomass carbon than areas with temperature below 10℃. Moreover, as for no-tillage years, long-term no-tillage (no-tillage years ≥8a) showed the strongest positive influence on soil microbial biomass carbon. The findings revealed that regional differences existed in the positive effects of no-tillage on soil microbial biomass carbon, and varied with different water moisture, temperature,and no-tillage year. Therefore, based on the regional characteristics of no-tillage areas, the adaptability of no-tillage practice should be considered properly for future farmland utilization. Keywords: no-tillage, soil microbial carbon, Meta-analysis, regional effect