Molecular Soil Biology 2025, Vol.16, No.3, 103-113 http://bioscipublisher.com/index.php/msb 106 4.1.2 Impact on physical and chemical properties of soil Organic amendments can keep soil pH, electrical conductivity (EC) and nutrients such as nitrogen, phosphorus and potassium in an appropriate range, increase organic carbon content and make soil structure more stable (Ardebili and Sharifi, 2018; Yang et al., 2022; Liu et al., 2023). Some studies have found that irrigation with wastewater can also increase organic matter, major nutrients and some trace elements in the soil, and will not cause excessive accumulation of heavy metals (Gurjar et al., 2023). 4.2 Microbial Inoculants 4.2.1 Biofertilizers (e.g., nitrogen fixers, phosphate solubilizers) Some biofertilizers, such as nitrogen-fixing bacteria, phosphate-solubilizing bacteria and potassium-solubilizing bacteria, can be used with a little chemical fertilizer to reduce the amount of chemical fertilizers and increase flower yields and income (Kumar et al., 2022). If deep tillage and bio-organic fertilizers are added, chrysanthemum will grow better, and the number of beneficial bacteria in the soil, such as Pseudomonas and Bacillus, will also increase (Chen et al., 2020). 4.2.2 Mycorrhizal fungi and plant-growth-promoting rhizobacteria (PGPR) There are also some species, such as cyanobacteria, Trichoderma, nitrogen-fixing bacteria, etc., which can increase the soil's microbial biomass carbon, nitrification capacity and the activity of various enzymes, which can help chrysanthemum grow faster, take root better, and make the soil more fertile (Prasanna et al., 2016). These microorganisms can also improve the species and structure of microorganisms around the roots (Prasanna et al., 2016; Chen et al., 2020; Yang et al., 2022). 4.3 Cover Cropping and Green Manuring 4.3.1 Leguminous and non-leguminous green manures Intercropping corn and chrysanthemum is a relatively effective method. It can increase the number of beneficial bacteria such as Bacillus and Sphingomonas, and also increase nutrients such as nitrogen, potassium, copper, and zinc in the soil, thereby helping chrysanthemum grow better and the flowers have better quality (Liao et al., 2024) (Figure 2). 4.3.2 Soil structure improvement and nutrient cycling Growing green manure or covering crops can also help improve soil structure, make the soil looser and the aggregates more stable. They can also promote nutrient circulation, make enzyme activity stronger, and increase the number of microorganisms (Yang et al., 2022; Liao et al., 2024). 4.4 Physical Methods 4.4.1 Soil solarization and mulching using biodegradable materials Combining deep tillage, bio-organic fertilizer and soil fumigation methods can regulate the types and proportions of microorganisms in the soil, improve enzyme activity and nutrient utilization efficiency, and promote the healthy growth of chrysanthemum (Chen et al., 2020). 4.4.2 Reduced tillage effects Reducing the frequency of tillage is very helpful in protecting soil structure. This can maintain organic matter in the soil and is also conducive to microbial diversity. In this way, the roots of chrysanthemums can grow better and the soil quality will be improved (Yang et al., 2022). 5 Mechanisms of Action in Enhancing Soil Quality 5.1 Nutrient release and retention Eco-friendly improvement methods can help the soil release and retain nutrients in many ways. For example, using rice husks and leaf mold instead of peat can not only make the physical and chemical properties of the soil more stable, but also maintain the appropriate pH, electrical conductivity (EC) and the levels of major nutrients such as nitrogen, phosphorus and potassium, so that chrysanthemum grows better and photosynthesis is stronger (Liu et al., 2023). Deep tillage and bio-organic fertilizers can increase the available nitrogen, phosphorus and
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