State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P.O. Box 821, Nanjing, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China; Department of Chemistry, University of Buea, P.O. Box 63, Buea, Cameroon.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P.O. Box 821, Nanjing, China.
Environ Pollut. 2020 May;260:114049. doi: 10.1016/j.envpol.2020.114049. Epub 2020 Jan 23.
Acidification in variable charge soils is on the rise due to increased acid deposition and use of nitrogenous fertilizers. The associated low pH and cation exchange capacity make the soils prone to depleted base cations and increased levels of Al. Consequently, Al toxicity to plants and soil infertility decrease crop yield. This study was designed to investigate the effect of Pseudomonas fluorescens on the acidification of two Ultisols. The simulated acidification experiment demonstrated that the pH of bacteria-treated soil was higher than that of control under similar conditions, suggesting that the adhered bacteria inhibited soil acidification. This observation was attributed to the association of organic anions (RCOO or RO) on bacteria with H to form neutral molecules (RCOOH or ROH) and reducing the activity of H in solution. The bacteria also inhibited the increase in soil soluble Al and exchangeable Al during soil acidification. The adhesion of bacteria on the soils increased soil effective cation exchange capacity (ECEC) and exchangeable base cations at each pH compared to control. The release of exchangeable base cations from bacteria-treated soil, and the decrease in soil ECEC and exchangeable base cations with decreasing pH confirmed that protonation of organic anions on adhered bacteria was mainly responsible for the inhibition of soil acidification. The change of zeta potential of the bacteria with pH and the ART-FTIR analysis at various pH provided more evidence for this mechanism. Therefore, the bacteria in variable charge soils played an important role in retarding soil acidification.
由于酸性物质的沉降和氮肥的使用，可变电荷土壤的酸化问题日益严重。相关的低 pH 值和阳离子交换量使土壤容易缺乏基础阳离子和增加铝含量。因此，铝对植物的毒性和土壤贫瘠会降低作物产量。本研究旨在研究荧光假单胞菌对两种土壤酸化的影响。模拟酸化实验表明，在相似条件下，细菌处理过的土壤的 pH 值高于对照土壤，表明附着的细菌抑制了土壤酸化。这一观察结果归因于细菌上的有机阴离子（RCOO 或 RO）与 H 结合形成中性分子（RCOOH 或 ROH），从而降低了溶液中 H 的活性。细菌还抑制了土壤酸化过程中土壤可溶性铝和可交换铝的增加。与对照相比，细菌在土壤中的附着增加了每个 pH 值下土壤有效阳离子交换量（ECEC）和可交换基础阳离子的含量。从细菌处理过的土壤中释放出可交换的基础阳离子，以及随着 pH 值降低，土壤 ECEC 和可交换基础阳离子的减少，证实了附着在细菌上的有机阴离子的质子化主要负责抑制土壤酸化。细菌的 ζ 电位随 pH 值的变化以及在不同 pH 值下的 ART-FTIR 分析为这一机制提供了更多证据。因此，可变电荷土壤中的细菌在减缓土壤酸化方面发挥了重要作用。
