Changes in soil organic carbon and microbial community under varying straw incorporation strategies

• Published in: Soil & tillage research 2020-10, Vol.204, p.104735, Article 104735
• Main Authors: Cong, Ping, Wang, Jing, Li, Yuyi, Liu, Na, Dong, Jianxin, Pang, Huancheng, Zhang, Li, Gao, Zhijuan
• Format: Article
• Language: English
• Subjects: Maize straw return; Microbial diversity and abundance; Soil organic carbon fractions; Straw forms; Subsoil
• ISSN: 0167-1987; 1879-3444
• DOI: 10.1016/j.still.2020.104735

•Different forms of deep-buried straw strongly affected C fractions in subsoil.•Microbial biomass carbon and dissolved organic carbon were more sensitive to different forms of straw return.•Changes in C fractions and physicochemical properties strongly affected microbial distribution.•Straw return improved C fractions by regulating C-related microbial abundance. Straw return is a popular management strategy to improve soil organic carbon (SOC) and change soil microbial community structure in agro-ecosystems. In the North China plain, the average straw incorporation rate is 6000–10,000 kg ha−1, however, effective utilization of maize straw is difficult because of its large amount and volume. A four-year (2014–2017) experiment was conducted to investigate the effects of different forms of maize straw on subsoil SOC fractions and microbial communities under deep-buried (30–40 cm) management in a typic Agrosol in Liaohe plain. Six treatments were established: no straw (CK, 0 kg ha−1), whole straw (WS, 6000 kg ha−1), chopped straw (CS, 6000 kg ha−1), pelletized straw (PS, 6000 kg ha−1), straw biochar (BC, 2010 kg ha−1) and straw ash (SA, 960 kg ha−1). Soil organic carbon, dissolved organic carbon (DOC), microbial biomass carbon (MBC), and bacterial and fungal diversity and abundance were analysed by chemical and molecular methods. Compared with CK, the five treatments significantly increased the SOC pool by 1.4–4.8 % in the 0–20 cm soil depth and 3.2–14.2 % in the 20–40 cm depth, with the highest increase under CS. Both CS and WS significantly increased the DOC and MBC, with higher DOC/SOC and MBC/SOC ratios. Notably, straw incorporation showed greater effects on DOC and MBC and a higher increase in SOC fractions in the 20–40 cm depth. Principal component analysis and similarity analysis showed that the different forms of straw incorporation caused significant variations in microbial community structure in the subsoil layer. The BC and SA significantly increased the diversity of soil microorganisms, while CS and WS altered the relative abundance of the dominant bacterial phyla Acidobacteria, Nitrospirae, Proteobacteria, Verrucomicrobia and dominant fungal phyla Ascomycota, Morttierellomycota, Glomeromycota, which increased with increases in SOC fractions. Our results showed that regulation of C-related microbial abundance in the subsoil was more conducive to improving SOC fractions than simply improving soil microbial diversity. Since chopped straw significantl