Molecular Soil Biology 2025, Vol.16, No.4, 214-229 http://bioscipublisher.com/index.php/msb 218 provide more trace elements, which is more beneficial to plants (Dhaliwal et al., 2019; Yu et al., 2024; Huang et al., 2025; Valencia et al., 2025). These improvements provide a better growth environment for Leonurus 'Boy'. 5.2 Enhancement of microbial communities. Soil improvement not only improves physical properties, but also makes microorganisms richer and more functional. Using organic fertilizers, biochar, microbial agents or effective microorganisms (EM) can increase the number and types of bacteria and fungi in the soil, and can also improve enzyme activity and microbial metabolic capacity (Liang et al., 2018; Bossolani et al., 2021; Fall et al., 2022; Kong and Lu, 2023; Chen et al., 2025; Liu et al., 2025). Using EM and straw together can greatly increase the diversity of microorganisms and enhance the activity of soil enzymes. Beneficial bacteria (such as nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and potassium-solubilizing bacteria) will reproduce faster and inhibit some harmful bacteria (Liang et al., 2018; Chen et al., 2025; Liu et al., 2025). When biochar and organic fertilizer are used together, the microbial structure can be more reasonable, which is conducive to the carbon and nitrogen cycle in the soil and accelerates the decomposition of organic matter (Bossolani et al., 2021; Singh et al., 2022; Aminzadeh et al., 2025). Some fungi, such as arbuscular mycorrhizal fungi (AMF), can also secrete colloids and organic acids, which will promote the formation of aggregate structure and improve the soil's ability to supply nutrients (Fall et al., 2022; Aminzadeh et al., 2025) (Figure 1). The improvement of these microorganisms can make the soil ecosystem stronger and is also conducive to the healthy growth of "children". Figure 1 Effects of arbuscular mycorrhizal fungi on improving soil fertility (Adopted from Fall et al., 2022) 5.3 Reduction of salinity/toxicity in reused off-season soils. Sometimes, farmland is reused for planting after the fallow season, but at this time the soil often accumulates salt and some harmful substances, which are not very friendly to plants. However, studies have shown that these problems can be effectively reduced through improvement measures. The use of gypsum, acidified biochar, organic fertilizer, fly ash, microbial agents, etc. can reduce soil salinity, electrical conductivity (EC), exchangeable sodium percentage (ESP) and some toxic ions (such as Na+, Al3+) (Abdolvand and Sadeghiamirshahidi, 2024; An et al., 2024; Guan et al., 2024; Yu et al., 2024; Huang et al., 2025) (Figure 2). Gypsum and biochar can reduce EC by 8.6% to 33.6%, ESP by 43.4%, and pH by 0.1 to 1.5 units on saline-alkali land (Guan et al., 2024; Yu et al., 2024; Huang et al., 2025). Organic fertilizers and microbial agents can also help decompose harmful substances
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