盐碱土改良利用攻关研究【华中农大最新出版】：沿深度梯度探究铁改性生物炭对盐碱土壤化学性质和细菌群落的改善作用

ABSTRACT

The application of modified biochar has been proven to be a novel and promising strategy to improve saline-alkali soil. However, the effect of iron-modified biochar (FB) on the chemical properties of saline-alkali soil at different depths remains unclear. Therefore, we designed a soil column that divides the soil into three consecutive parts to explore the amelioration effect of iron-modified biochar on saline-alkali soil chemical properties and the response of bacterial communities along a depth gradient. The results showed that soil chemical properties were significantly improved with 1% FB application, while the amelioration effect of FB was different between topsoil and subsoil. A significant increment in activities of extracellular enzymes in topsoil and decrease in base cations in subsoil were observed in 1% FB treatment. Moreover, the abundances of halophilic taxa were higher in subsoil than in topsoil, especially for the phyla Bacteroidetes and Deinococcus. Furthermore, the abundance of beneficial bacteria (e.g., Alphaproteobacteria, Sphingomonas, and Pontibacter) in saline-alkali soil increased at 1% FB. Our results suggest the influence of iron-modified biochar on soil properties and bacterial communities along a soil depth gradient, providing a novel strategy for improving saline-alkali soil with biochar.

Key Words: base cations, extracellular enzyme, salinization, salt movement, soil depth

中文摘要

应用改性生物炭已被证明是一种新颖且具有前景的盐碱土壤改良策略。然而，铁改性生物炭（FB）对不同深度盐碱土壤化学性质的影响尚不明确。因此，我们设计了一个将土壤分为三部分的土柱来探讨铁改性生物炭对不同深度盐碱土壤化学性质改良效果以及细菌群落在深度梯度上对其的响应。结果表明，1% FB处理显著改善了土壤的化学性质，但FB在表层土壤和底层土壤中的改良效果不同。1% FB处理显著增加了表层土壤中胞外酶的活性，同时减少了底层土壤中的基本阳离子。此外，在底层土壤中，嗜盐菌的丰度高于表层土壤，尤其是拟杆菌门和放线菌门。此外，1% FB处理显著增加了盐碱土壤中有益细菌（如α-变形菌纲、鞘脂单胞菌属和红细菌属）的丰度。研究结果表明，铁改性生物炭对沿土壤深度梯度的土壤性质和细菌群落具有影响，为用生物炭改良盐碱土壤提供了一种新策略。

关键词：盐基阳离子、胞外酶、盐碱化、盐分移动、土壤深度

表1 生物炭样品的基本性质

图2 在培养7天和28天后，传统生物炭（PB）和铁改性生物炭（FB）改良剂（剂量=0.5%和1%）对不同深度土壤的pH值（A）、土壤有机质（B）、电导率（C）、钠吸附比（D）以及包括钾离子（E）、钠离子（F）、钙离子（G）和镁离子（H）在内的碱性阳离子含量的影响。不同的小写字母表示在相同土壤深度和采样时间下处理之间存在显著差异（Duncan检验，P < 0.05）。双因素方差分析的统计结果以F值表示。* P < 0.05；** P < 0.01。

Fig. 2 Effects of PB and FB amendment (dosage = 0.5% and 1%) on soil pH (A), SOM (B), EC value (C), SAR (D), and the content of base cations, including K+ (E), Na+ (F), Ca2+ (G), and Mg2+ (H), in different depth soils after 7 and 28 d of incubation. Different lowercase letter indicated significant differences between treatments under the same soil depth and sampling time according to Duncan's test (P < 0.05). The statistical results of two- way ANOVA are expressed in F-value. * P < 0.05; ** P < 0.01.

Fig. 3 Activities of extracellular enzymes in different depth soils after 7 and 28 d of incubation. A: The activity of β-glucosidase (β-G); B: The activity of β-cellobiohydrolase (CBH); C: The activity of β-xylanase (β-X); D: The activity of N-acetyl-glucosaminidase (NAG). Different lowercase letter indicated significant differences between treatments under the same soil depth and sampling time according to Duncan’s test (P < 0.05). The statistical results of two-way ANOVA are expressed in F-value. * P < 0.05; ** P < 0.01.

Fig. 4  (A) Shannon diversity index in top and sub soils of the control, 1% PB, and 1% FB treatment after 28 d of incubation. P < 0.05 marked as *. (B) Principal Coordinates Analysis (PCoA) based on Bray-Curtis distance of the soil bacterial community composition. (C) Linear discriminant analysis Effect Size (LEfSe), showing significantly different abundant bacterial taxa in top and sub soils of different treatments. The discriminative taxa are represented by dots with different color, from the center outward, they represent the phylum, class, order, family, and genus levels.

图5 对照组（A）、1% PB组（B）和1% FB组（C）在28天后表层土壤和底层土壤中差异OTUs。每个点代表一个OTU。红点和绿点分别表示增加的OTU和减少的OTU。基于差异OTUs的细菌门相对丰度，在对照组（D）、1% PB组（E）和1% FB组（F）中的变化。

Fig. 5  Differential OTUs in top soil versus sub soil under the control (A), 1%PB (B), and 1%FB (C) treatments at 28 d. Each point represents a single OUT. The red and green points respectively represent enriched OUT and declined OUT. Relative abundances of bacterial phylum based on the differential OTUs in the control (D), 1% PB (E), and 1%FB (F) treatments at 28 d.

图6 在表层土壤（A）和底层土壤（B）中基于属水平的多组比较。对照组（C）、1% PB组（D）和1% FB组（E）中基于属水平的表层土壤和底层土壤的两组比较。*, ** 和 *** 分别表示在P < 0.05、P < 0.01 和 P < 0.001 水平上的显著性。

Fig. 6 Multi-group comparison based on genus level among treatments in top soil (A) and sub soil (B). Two groups of comparison based on genus level between top and sub soils in the control (C), 1%PB (D), and 1%FB (E) treatments. *, ** and *** represent significance at P < 0.05, P < 0.01 and P < 0.001, respectively.

图7 土壤化学性质与细菌类群在门水平（A）和属水平（B）的相关性分析。红色表示正相关，绿色表示负相关。*, ** 和 *** 分别表示在P < 0.05、P < 0.01 和 P < 0.001 水平上的显著性。

Fig. 7 Correlation analysis of soil chemical properties with phylum (A) and genus level (B) of bacterial taxa. Red colors indicate positive correlations, while green colors indicate negative correlations. *, ** and *** represent significance at P < 0.05, P < 0.01 and P < 0.001, respectively.

长按二维码 畅读全文