Molecular Soil Biology 2025, Vol.16, No.3, 103-113 http://bioscipublisher.com/index.php/msb 110 (Prasanna et al., 2016; Chen et al., 2020; Yang et al., 2022). If properly managed, wastewater irrigation can also increase organic matter and trace elements in the soil, but be careful not to let heavy metals accumulate too much (Gurjar et al., 2023). Intercropping can also enrich beneficial microorganisms, help nutrient cycling, reduce the occurrence of pests and diseases, and reduce the use of pesticides (Liao et al., 2024). Prasanna et al., 2016）。 8 Case Study: Field Application of Biochar and PGPR in a Commercial Chrysanthemum Farm 8.1 Location and soil background This case was conducted on a farmland that had been planted with chrysanthemum for eight years. Due to continuous planting, the land had more and more problems, such as rapid water loss, less nutrients, low soil pH, and the accumulation of many harmful microorganisms (Feng et al., 2024). 8.2 Description of the treatment setup (biochar + PGPR vs. control) The experiment was divided into two groups. One group used biochar (such as straw, pig manure, and sludge) plus PGPR inoculants (such as Bacillus subtilis and Pseudomonas aeruginosa), and the other group did not add these two things and served as the control group (Feng et al., 2024; Wang et al., 2024). Biochar was mixed into the soil in proportion, and PGPR inoculants were applied by irrigation or seed mixing. 8.3 Quantitative results (soil metrics, plant performance) After adding biochar and PGPR, the soil water retention capacity was significantly enhanced, and the water retention rate increased by 18.4% to 25.4% (Feng et al., 2024). The available phosphorus in the soil increased by 85%, potassium increased by 164%, and the nitrogen content also increased significantly. The pH value of the soil increased by 0.4% to 5.4%, indicating that the acidity was alleviated. There were more good bacteria, such as actinomycetes and Nocardia; and fewer bad bacteria, such as basidiomycetes and spores. The growth of chrysanthemum was also better, and the ability to absorb nitrogen, phosphorus and potassium was enhanced. Indicators such as plant height, fresh weight, and flower diameter were higher than those of the control group (Ali and Mjeed, 2017; Wang et al., 2024). The disease resistance of the plants was also improved, and the related defense genes were upregulated (Wang et al., 2024). 8.4 Farmer perspectives and challenges Many farmers said that the use of biochar and PGPR together can indeed improve soil structure, reduce diseases, increase yield and quality, and use less fertilizer, making more money (Feng et al., 2024). However, there are also some difficulties. For example, the raw materials of biochar are difficult to select and the cost of use is a bit high. The activity of PGPR inoculants is also difficult to control during storage and in the field (Feng et al., 2024; Wang et al., 2024). 8.5 Lessons learned and scalability This case shows that the use of biochar and PGPR together is better than using either one alone. They can continuously improve the soil of continuous cropping and increase the yield and quality of chrysanthemum (Feng et al., 2024; Wang et al., 2024). They can also help make the microbial system in the soil more stable and healthier (Feng et al., 2024; Wang et al., 2024). If this method is to be promoted, the usage and ratio of biochar and PGPR should be adjusted according to local soil types, crop varieties and farmers' economic capabilities to make it more practical and cost-effective. 9 Challenges and Research Gaps 9.1 Variability in microbial inoculant performance There are indeed many benefits to using microbial inoculants when growing chrysanthemum. They can increase enzyme activity in the soil, increase the variety of microorganisms, and make the plants grow better (Prasanna et al., 2016; Chen et al., 2020; Liao et al., 2024). However, different species of bacteria, such as cyanobacteria, bacteria, and fungi, perform differently in different soils and environments. Some have very good effects, while others are less obvious or even much worse (Prasanna et al., 2016; Liao et al., 2024). Moreover, the effects of
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