生物质炭对草坪土壤微生物碳代谢群落结构的影响

【目的】探明不同用量生物质炭对草坪土壤微生物多样性特征的影响，为生物质在草坪土壤中的应用提供理论依据。【方法】以草坪土壤为研究对象，以不施用生物质碳为对照，设8、20、40和200 kg/m2共4个生物质炭用量处理，对照和4个处理分别标记为BC0、BC8、BC20、BC40和BC200。播种5个月后采集0~30 cm土壤，测定土壤有机碳、全氮、水溶性碳和微生物量碳含量及土壤微生物碳代谢群结构，分析不同用量生物质炭对草坪土壤微生物碳代谢群落的影响。【结果】与对照BC0相比，施用生物质炭处理的土壤全氮含量显著增加（P<0.05，下同），BC40和BC200处理的土壤有机碳显著增加，BC200处理的水溶性碳显著增加，而土壤微生物量碳无显著变化（P>0.05）。BC20处理的土壤平均光密度（AWCD）值较对照BC0提高12.4%，BC200处理的AWCD值则较对照降低51.3%。BC20处理增加了生物群落结构AWCD值，利用胺类物质微生物活性显著提高；BC200处理降低了土壤微生物数量，对利用多聚物类物质微生物的负面影响最小。主成分分析结果表明，第一主成分可解释变异的86.06%，主要为代谢吐温40、吐温80、L-丝氨酸、D-半乳糖酸内脂、D，L-α-磷酸甘油和4-羟基苯甲酸等六种碳源物质引起的，能有效区分适量（BC8、BC20、BC40）和过量（BC200）施用生物质炭含量处理的草坪土壤。相关分析结果表明，土壤微生物量碳与i-赤藓糖醇的光密度值呈显著正相关；土壤有机碳和水溶性碳含量与L-精氨酸、L-丝氨酸等多种碳源的光密度值呈显著或极显著（P<0.01）负相关。【结论】适量施用生物质炭可提高草坪土壤的微生物数量和活性。施用生物质炭的草坪土壤利用L-精氨酸、L-天门冬酰胺的能力较强，但对利用L-苏氨酸、i-赤藓糖醇、D-木糖和2-羟基苯甲酸等碳源基质的利用能力较弱。建议在种植草坪草时，生物质炭的施用量控制在20 kg/m2以内。

Effects of biomass carbon on microbial carbon metabolic community structure in turf-grass soil

【Objective】 To explore the effects of different amounts of biochar on the microbial diversity characteristics of turf-grass soil, and to provide a theoretical basis for the application of biomass in turf-grass soil.【Method】 Taking turfgrass soil as the research object and no biochar as the control, four biochar dosage treatments of 8, 20, 40 and 200 kg/m2 were set, control and four treatments were marked as BC0, BC8, BC20, BC40 and BC200. After 5 months of sowing, 0-30 cm soil was collected, the contents of soil organic carbon, total nitrogen, water-soluble carbon, microbial biomass carbon and the structure of soil microbial carbon metabolism group were measured, and the effects of different amounts of biochar on turf-grass soil microbial carbon metabolism community were analyzed.【Result】 Compared with the control BC0, the total nitrogen content of soil treated with biochar increased significantly(P<0.05, the same below), the soil organic carbon of BC40 and BC200 increased significantly, the water-soluble carbon of BC200 increased significantly, but the soil microbial biochar did not change significantly(P>0.05). The average well color development(AWCD) of soil treated with BC20 was 12.4% higher than that of the control BC0, and the AWCD value of soil treated with BC200 was 51.3% lower than that of the control. BC20 increased the average optical density of biological community structure, and the microbial activity was significantly improved due to the use of amines;BC200 reduced the number of soil microorganisms and had the least negative impact on the use of polymer microorganisms. The results of principal component analysis showed that the first principal component could explain 86.06% of the variation. It was caused by six carbon source substances such as tween 40, tween 80, L-serine, D-galactose acid lipid, D, L-α-glycerophosphateand 4-hydroxybenzoic acid, which could effectively distinguish turf-grass soil treated with appropriate amount(BC8, BC20, BC40) and excessive(BC200) biochar content. The results of correlation analysis showed that there was a significant positive correlation between soil microbial biochar and the optical density of i-erythritol. The contents of soil organic carbon and water-soluble carbon were significantly or extremely(P<0.01) negatively correlated with the optical density of L-arginine, L-serine and other carbon sources.【Conclusion】 Appropriate application of biochar can improve the number and activity of microorganisms in turf-grass soil. The turf-grass soil with biochar has strong ability to utilize L-arginine and L-asparagine, but weak ability to utilize carbon source substrates such as L-threonine, i-erythritol, D-xylose and 2-hydroxybenzoic acid. It is suggested that when planting turf-grass grass, the application amount of biochar should be controlled within 20 kg/m2.