The responses of soil organic carbon mineralization and microbial communities to crop residue-derived dissolved organic matter (DOM) addition with fresh and aged biochar soil amendments

Dr Jufeng Zheng1, Dr Zhiwei Liu

1Nanjing Agricultural University, Nanjing, China

In the present study, a 6-year field experiment was carried out with a one-time biochar amendment at the rate of 40 t ha-1 in a typical paddy soil in southeastern China. Soil samples with (BA) and without (CK) biochar amendment were collected for the incubation experiment in the laboratory, which was designed as two-factorial of biochar and crop residue-derived dissolved organic matter (CRM) and included six treatments: 1) soil only (Control), 2) soil + fresh biochar (SFB), 3) aged biochar soil (SAB), 4) soil only + CRM (S-CRM), 5) soil + fresh biochar + CRM (SFB-CRM), and 6) aged biochar soil + CRM (SAB-CRM). The soil CO2 release dynamics were observed across the whole incubation period, and microbial phospholipid fatty acid (PLFA) abundance was determined at the end of incubation. The results showed that the amount of SOC mineralization compared to the control decreased significantly, by 38.8%, under the SAB treatment, while it increased by 28.9% under the SFB treatment. However, significant suppression of relative SOC mineralization was observed under the biochar amendment treatments, and the suppression increased with biochar aging under CRM addition. Moreover, fresh biochar addition significantly increased the total abundance of PLFAs. No notable changes in PLFA between the SAB treatment and the control were observed, although the microbial community composition shifted due to biochar amendment. Lastly, the lower metabolic quotient in biochar-amended soil was related to the duration of biochar presence in soil, suggesting that biochar amendment could enhance the soil microbial utilization efficiency of carbon in the long-term. Therefore, SOC sequestration can be improved over longer periods of biochar presence in soil.


Biography:

Dr. Jufeng Zheng is a soil scientist on SOM and carbon biogeochemical cycling. He obtained a PhD degree from the NAU in 2007. Since then he has been working on SOM mineralization and greenhouse gases emission from croplands, focusing on C and N changes under land use change, GHGs mitigation with best management practices in agricultural soils.

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