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Xu Xuexuan's Team Has Made Important Progress in the Generation Mechanism of Soil Water Repellency in Loess Region

Update time:2022-10-11

Recently, Xu Xuexuan's research team published a paper entitled " Physicochemical and biological factors determining the patchy distribution of soil water repellency among species of dominant vegetation in loess hilly region of China " in Frontiers in Plant Science (IF2021: 6.627), the top journal in the biological field. Chai Xiaohong, a doctoral student, is the first author of the paper, and Xu Xuexuan is the corresponding author.

Soil water repellency (SWR) is a physical phenomenon whereby water cannot penetrate or has difficulty penetrating the soil surface. There are many factors involved in its occurrence, but the main factors controlling its emergence in loess remain unclear. The investigation of various woodlands in Changwu Station had been done and it showed that: more than 75% of the soils under Robinia and Hippophae were categorized as slightly or strongly water repellent, while nearly 50% of the soils under Pinus were categorized as severely to extremely water repellent. The differences of soil microbial and organic components in Pinus, Robinia and Hippophae were studied to analyze the substances causing the difference of water repellency under three vegetation types by gas chromatography–mass spectrometry (GC-MS) and high-throughput sequencing techniques. The relative concentrations of total free lipids in the soil in the same water-repellency class were Pinus > Robinia > Hippophae, where fatty acids, alkanols, and sterols were positively correlated with SWR, whereas alkanes were not. For the abundance and diversity index of bacterial and fungal communities, the three species ranked in the following order: Pinus < Robinia ≈ Hippophae. Therefore, the relatively lower soil microbial diversity under Pinus makes polar wax better preserved in the soil, showing stronger water repellency. Moreover, the abundance of Actinobacteria in dominant bacteria increased with SWR, and the difference of fungal community may be another reason why the soil water repellency under Pinus is greater than that under Robinia and Hippophae; this finding was further supported by the linear discriminant analysis (LDA) effect size (LEfSe). These pieces of evidence collectively reveal that severe to extreme SWR occurs under Pinus and appears to be the most influenced by fungi and actinomycetes when the topsoil is close to air drying. This study has put forward new ideas on the interaction between plants and microorganisms affecting the occurrence of soil water repellency.

This research was supported by the National Natural Science Foundation of China (Grant No. 41977426).

To view the online publication, please click here:http://journal.frontiersin.org/article/10.3389/fpls.2022.908035/full?&utm_source=Email_to_authors_&utm_medium=Email&utm_content=T1_11.5e1_author&utm_campaign=Email_publication&field=&journalName=Frontiers_in_Plant_Science&id=908035

FIGURE 1 A contour map of soil water-repellence classes beneath Pinus (A–C), Robinia (D–F), and Hippophae (G–I). Numbers 0, 1, 2, 3, and 4 represent wettable, slightly water-repellent, strongly water-repellent, severely water-repellent, and extremely water-repellent soils, respectively.

FIGURE 2 The correlation between plants, microorganisms, and SWR.