Soil Microorganisms Can Reduce P Loss from Cropping Systems

Can we reduce phosphorus runoff from agricultural fields by stimulating soil biota?

“…This relationship is consistent with the other studies that show that soil biota may have limited influence on instantaneous P pools but may provide a long-term sustained source of P that is accessible to plants (Lehman & Taheri, 2017;Mader et al, 2002). In fact, in systems with increased organic matter and biological activities, the predictive power of traditional instantaneous measures of inorganic soil P (e.g., Olsen P) on plant P uptake decreases (Lehman & Taheri, 2017). This is because more P is held in microbial and organic pools that are not detected by these tests and are cycled into plant-available pools slowly over time (Lehman & Taheri, 2017).…”

“…Unlike the instantaneous measures of P availability, cumulative resin P was positively correlated with average microbial respiration and PHOS activities. This relationship is consistent with the other studies that show that soil biota may have limited influence on instantaneous P pools but may provide a long-term sustained source of P that is accessible to plants (Lehman & Taheri, 2017;Mader et al, 2002). In fact, in systems with increased organic matter and biological activities, the predictive power of traditional instantaneous measures of inorganic soil P (e.g., Olsen P) on plant P uptake decreases (Lehman & Taheri, 2017).…”

“…The authors concluded that much of this change was driven by arbuscular mycorrhizal fungi (Bender & van der Heijden, 2015). However, mycorrhizae are unlikely to be present in large concentrations in the conventionally managed agricultural soil (Lehman & Taheri, 2017) of this study. We propose that the relatively low abundances and activities of organisms that solubilize P, and low organic matter content (2% soil organic matter content compared F I G U R E 5 Cumulative resin P vs. plot mean for (a) microbial biomass C, (b) microbial respiration, and (c) potential phosphatase activities.…”

“…In fact, in systems with increased organic matter and biological activities, the predictive power of traditional instantaneous measures of inorganic soil P (e.g., Olsen P) on plant P uptake decreases (Lehman & Taheri, 2017). This is because more P is held in microbial and organic pools that are not detected by these tests and are cycled into plant-available pools slowly over time (Lehman & Taheri, 2017). Although we cannot conclusively determine whether higher microbial activities were the cause or effect, or correlate, of elevated P accessibility, this result provides some limited support for the idea that soil biota can provide a sustained source of P for plants through immobilization and gradual release.…”