Despite the large scale implementation of conservation schemes aimed at reducing phosphorus (P) loss
from agricultural lands, significant improvements in water quality at the watershed scale remain elusive.
Changes in land management influence the speciation and cycling of P within soils and recent promotion
of conservation practices to improve soil health revolve around increasing soil carbon stores, thereby
increasing the pool of soil organic P. Adopting conservation tillage, use of cover crops, strategic crop
rotations, and use of manures can increase organic P by 3–180% and microbial biomass pool of P by
30–240%. The role of organic P in soil fertility has been largely ignored in current soil testing methods,
which in many cases may explain the lack of crop response to recommended fertilizer inputs in a growing
number of trials. Conversely, soil organic P is gaining recognition as a potential source of P to runoff.
This review explores the impact of adopting widely promoted “soil health” conservation practices on
the speciation and cycling of soil P, with particular focus on the organic pool and the biotic processes
regulating its accumulation and mobilization. Large stores of organic P exist in arable and grassland soils
and strategies that increase the plant availability of these P stores could reduce the reliance on external P
inputs, creating more sustainable P use. However, more detailed, mechanistic knowledge of soil organic
P cycling, especially through the microbial biomass, is required. Furthermore, caution is needed to ensure
that increasing the availability of organic P does not increase P loss in runoff effectively turning P sinks
into P sources.