**2. Contributions of phosphate-solubilizing bacteria (PSB) and arbuscular mycorrhizal fungi (AMF) in improving P availability**

A better understanding of how the beneficial microbes (PSB and AMF) and phosphate rock interact is crucial to preserving the soil fertility and improving the *Phosphate Solubilization Improvement for Plant Uptake from Phosphate Rock and Phosphate… DOI: http://dx.doi.org/10.5772/intechopen.107029*

economic and environmental sustainability of crop production in P-deficient soils [14]. Previous studies have reported that SiO2 is not the major constituent of RP but CaO (51.23%) [15] and could increase plant uptake of P. Combining Si and microorganisms application has been proposed to effectively induce and improve plant growth and nutrition [16–18]. It was earlier observed that AMF and Si (from SiO2—a constituent of RP) work together to improve plant growth regardless of stress conditions. Similarly, PBS and SiO2 synergistically help plants better uptake P [19, 20]. Another study indicates that SiO2 contained in the rock phosphate is a quasi-essential nutrient and is beneficial to plants, especially when under different stresses such as drought, heavy metal toxicity, nutritional imbalance, plant pathogens, and salinity [21]. Si fertilization increases P levels in different crops and improves plant growth by enhancing P availability for plants [22]. PBS generally have the ability to weather silicates, likely because basic metabolic activities such as organic acids production and respiration can cause the weathering of minerals [23].
