Closing the Loop on Phosphorus Loss from Intensive Agricultural Soil: A Microbial Immobilization Solution?

Phosphorus (P) fertilizer has been applied profligately across the globe, being particularly overused in China in the past 30 years in order to pursue high yields (Cordell et al., 2009; Li et al., 2014). This has greatly increased the P content of soil in various intensive agricultural systems (including cereals, vegetables, and fruit orchard), many of which now contain sufficient P to potentially supply P for adequate yields in these crops for several years (Li et al., 2011; Tóth et al., 2014). For example, the soil available P in some cereal crop, vegetable and orchard systems in China have arrived at 24.7, 181, and 43.1mg kg−1, respectively (Lu, 2009; Li et al., 2011; Kalkhajeh et al., 2017). Over-application of P fertilizer is in itself wasteful, but the transport of excessive P from soil solution to the waterbodies by surface runoff and leaching causes various environmental problems, including eutrophication of lakes, rivers and near coastal zones, pollution of ground water aquifers, algal blooms, and the loss of terrestrial and aquatic biodiversity (Chen et al., 2008; Schoumans et al., 2014; Smith et al., 2015). Consequently, it is imperative to understand how best to immobilize P in the soil to avoid its loss to the wider environment. This is an urgent environmental issue that should be considered as a priority in intensive agricultural systems across the globe, but particularly in China.