Advances of mechanisms and technology pathway of efficient utilization of medium-low grade phosphate rock resources

Phosphate rock is raw material for phosphate fertilizer production, which is one of the most important strategic non-renewable resources. High grade phosphate rock is mined excessively, leading rapid depletion, and rich ore resources are exhausting. How to make full use of medium-low grade phosphate rock is critical for sustainable phosphorus-resource usage. Medium-low grade phosphate rock reserves are large, but the available phosphorus content is relatively low. To improve phosphorus (P) use efficiency, P mobilization is the core of the comprehensive utilization of medium-low grade phosphate rock. In most cases, utilization of low and medium grade phosphate rocks can mainly lay emphases on physical and chemical mobilization approaches, whereas the rhizosphere effects of plants in P mobilization are largely neglected. Plants can mobilize and uptake nutrients through the regulation of root morphology and physiology, and the interaction of rhizosphere. This is an important way of improving the efficient utilization of phosphorus resources by rhizosphere processes-based biological mobilization. This paper summarized the main approaches of improving the integrated use efficiency of medium-low grade phosphate rock. It is proposed that enhancing crop rhizosphere effect and exploring biological potential of plants can improve the comprehensive utilization of low and medium grade phosphate rocks. This pape can provide a scientific basis for sustainable utilization of phosphorus resource. This paper has analyzed the underlying mechanisms and technology strategies of efficient utilization of low and medium grade phosphate rocks. Maximizing biological potential of plants to use P efficiently through rhizosphere regulation and matching P fertilizers with specific soils and plants to exploit "green" P fertilizers could be effective ways to achieve sustainable development of P resources use. Moreover, further study on how to make full use of all nutrients from phosphate rock is also needed in the future.