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Organic carbon quality, composition of main microbial groups, enzyme activities, and temperature sensitivity of soil respiration of an acid paddy soil treated with biochar

Author:
Chen, Junhui, Chen, De, Xu, Qiufang, Fuhrmann, Jeffry J., Li, Lianqing, Pan, Genxing, Li, Yongfu, Qin, Hua, Liang, Chenfei, Sun, Xuan
Source:
Biology and fertility of soils 2019 v.55 no.2 pp. 185-197
ISSN:
0178-2762
Subject:
acid tolerance, bacteria, biochar, community structure, enzyme activity, fungi, hydrolysis, labile carbon, laboratory experimentation, magnetism, microbial communities, paddy soils, soil amendments, soil enzymes, soil respiration, spectroscopy, sulfuric acid, temperature
Abstract:
The role of soil organic C (SOC) quality affecting microbial community composition and function under biochar application is poorly understood. We investigated the relationship between the pool size and chemical composition of SOC; composition of main microbial groups; enzyme activities involved in C, N, and P cycling; and soil respiration in a rice paddy amended with biochar for 20 months in a laboratory experiment at 15, 25, and 35 °C. Soil labile and recalcitrant organic C pools were determined by a two-step sulfuric acid (H₂SO₄) hydrolysis method. The chemical composition of SOC was determined with ¹³C-nuclear magnetic resonance spectroscopy. The biochar amendment at 20 and 40 t ha⁻¹ significantly decreased the soil labile C pool I (extracted by 5 N H₂SO₄), alkyl, and carbonyl C contents and increased the recalcitrant C pool (acid-resistant) and aromatic C contents and the aromatic C to O-alkyl C ratio. The phospholipid-fatty acid concentrations and soil enzyme activities were unchanged by biochar application at 10 and 20 t ha⁻¹, but both were increased at 40 t ha⁻¹. Biochar increased the ratio of gram-positive (G+) to gram-negative (G−) bacteria and decreased that of fungi to bacteria. The recalcitrant C pool and aromatic C contents were positively correlated to the G+ bacteria abundance and were important factors in shaping composition of the main microbial groups and improving enzyme activities. Biochar application at 40 t ha⁻¹ lowered soil respiration rates at 15 and 25 °C by decreasing labile C pool and increasing C recalcitrancy while increased temperature sensitivities of soil respiration at 25/15 °C and 35/25 °C by stimulating microbial abundance and enzyme activities. Together, our results suggest that biochar soil amendment shifted microbial community composition and function through influencing the composition of SOC.
Agid:
6272735