Biochar promotes soil aggregate stability and associated organic carbon sequestration, and regulates microbial community structures in Mollisols from Northeast China
Abstract. Since the 1950s, heavy plowing of Mollisols, combined with a lack of organic matter intake, has resulted in severe soil degradation in Northeast China. The use of biochar in combination with fertilizer is a sustainable method of improving soil quality. In this paper, we conducted field experiments to explore the response of the stability mechanism of the soil aggregates, the dynamic properties of organic carbon, and changes in the microbial community structure to biochar. The biochar input levels were C1, C2, and C3 (9.8, 19.6, and 29.4 Mg·ha-1, respectively), while the nitrogen (N) fertilizer rates were N1/2 (300 kg·ha-1) and N (600 kg·ha-1). The field test showed that the C2N treatment increased the aggregate contents of the > 2 mm and 0.25–2 mm fractions by 56.59 and 23.41 %, respectively. The mean weight diameter increased by 41.53 %, while the geometric mean diameter increased by 21.62 %. The organic carbon content of large aggregates shows a greater increase, with an average of 28.14 %. The phospholipid fatty acids analysis revealed that bacteria (B) were the most prevalent organisms in the soil, followed by fungi (F). The C3N treatment increased the F / B ratio by 36.46 %, whereas the C3 treatment increased the gram-positive (Gm+)/gram-negative (Gm−) ratio by 19.67 %. We concluded that the response of Mollisols to biochar is primarily determined by the interplay of aggregates, organic carbon, and microorganisms. Based on the sequestration of SOC and the sustainability and stability of the ecosystem, we selected the optimal ratio for biochar and N fertilizer application and provide a scientific basis for the sustainable utilization of Mollisols resources.
Jing Sun et al.
Status: open (until 05 Apr 2023)
CC1: 'Comment on egusphere-2022-1084', Liang Jin, 09 Dec 2022
- AC1: 'Reply on CC1', jing Sun, 20 Dec 2022 reply
RC1: 'Comment on egusphere-2022-1084', Anonymous Referee #1, 02 Mar 2023
- AC2: 'Reply on RC1', jing Sun, 17 Mar 2023 reply
- RC2: 'Comment on egusphere-2022-1084', Anonymous Referee #2, 22 Mar 2023 reply
Jing Sun et al.
Jing Sun et al.
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The authors evaluated the effects of different biochar gradients combined with nitrogen fertilizer on the size, proportion, stability, and carbon content of Mollisols soil aggregates. In addition, they also examine how biochar affects the structure of microbial populations and identify the main factors influencing changes in microbial composition and recommend an optimal biochar application ratio to improve soil quality by modifying aggregates and the soil microbial community structure of Chinese black soils. They concluded that microbial abundance increased significantly when biochar and fertilizer were combined, and soil aggregation and SOC of black soil were significantly improved. The graphic description in the paper is relatively clear and intuitive, which well summarizes the conclusions expressed by the author.
Field experiments are a more objective reflection of actual production issues, and it is a pity that we did not see the author's research on crop yields, but it is still an impressive work, and the findings are essential if we want to improve our understanding of the improvement of soil quality through biochar. However, in my opinion, it is very necessary to make proper revisions before acceptance.
Line 16-23, The summary of the Abstract section, the conclusions seem ambiguous. I suggest that the author provide a clear and reliable conclusion in concise language.
Line 44-47, There is large room for improvement in description and expression. Some sentences are long and contain a lot of repetitive information.
Line 60-61, awkward sentence with controversial expression. Try to explain the limited time for straw decomposition.
Line 87, "Principal ecological activities including…", double check the term or phrase.
Line 215, Please explain original profiled soil?
Line 227, please define "bottom soil".
Line 230, "combined application"? unclear expression.
Line 288-290, Not necessary to simply repeat the numbers or values in the figures.
Line 342, macroaggregates, small macroaggregates? Please be uniform in the text.
Line 410, Among the effects of biochar combined with N fertilizer on microbial communities, the authors suggest the effectiveness of reduced N fertilizer application to improve microbial richness, and the potential negative environmental effects after high doses of N fertilizer application should be further briefly discussed.
Line 418, Please explain the difference between toc and SOC. Both parameters are used.
Line 426-428, Repeated statement.
Line 430-432, the meaning of this sentence is unclear, rephrase the sentences to make the logic smooth and the meaning clear.
Line 454, delete "The PCA showed that".