等碳投入的有机肥和生物炭对红壤微生物多样性和土壤呼吸的影响

施用有机肥是快速培育瘠薄土壤的一个重要措施。针对中亚热带第四纪红黏土发育的红壤旱地,建立了玉米和花生单作系统等碳量投入有机肥和生物炭的田间试验,利用聚合酶链式反应—变性梯度凝胶电泳(polymerase chain reaction-denaturing gradient gel electrophoresis,PCR-DGGE)方法研究了土壤细菌和真菌群落组成和多样性的变化,分析了土壤呼吸速率(CO2通量)的变化及其与微生物多样性的关系。两年的试验表明,不同施肥方式导致微生物群落结构显著分异,施用有机肥和生物炭显著增加了细菌多样性,但施肥第二年真菌多样性有下降趋势。秸秆和猪粪配施显著增加了土壤呼吸速率,土壤呼吸速率与细菌和真菌多样性呈显著正相关,细菌多样性对土壤呼吸的影响(相对贡献率为71%)显著高于真菌(29%)。土壤磷素(全磷和速效磷)含量的变化是驱动红壤微生物多样性变化的主导因素,其对细菌和真菌多样性的相对贡献率分别为44.8%和47.4%。因此,合理配施秸秆和猪粪可以快速提高瘠薄红壤的生物功能。

Effect of Organic Manure and Biochar with Equal Amount of Carbon Input on Microbial Diversity and Respiration of Red Soil

Improving the ecological functions of barren soils by organic manure is an important technology in soil fertility management. The effect of organic manure or biochar with equal carbon input was compared on soil microbial diversity and activity by using a field experiment in a red soil derived from Quaternary red clay in Subtropical China. Soil microbial diversity was measured by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE), than soil CO2 flux was observed to analyze its relationship with soil microbial diversity. The two-year experimental results showed that manure application altered significantly soil microbial community composition by changing soil properties. Applying organic manure and biochar increased the bacterial diversity, but decreased the fungal diversity in the second year. Fertilization could raise soil CO2 flux with the highest value under mixed application of organic manure and straw. Correlation analysis showed that soil respiration rate was significantly positively correlated to bacterial and fungal diversity, in which soil bacterial diversity played more contributions (71%) than fungal diversity (29%). Aggregated boosted tree (ABT) analysis showed that the relative contribution of soil phosphorus contents (total and available phosphorus content) to the variation of bacterial and fungal diversity were 44.8% and 47.4%, respectively, suggesting that different fertilization treatments influenced soil phosphorus supply and then drove the changes of microbial diversity. In total, mixed application of organic manure and straw can quickly improve red soil microbial diversity and functions.