Opportunities for mobilizing recalcitrant phosphorus from agricultural soils: a review

Background : Phosphorus (P) fertilizer is usually applied
in excess of plant requirement and accumulates in soils
due to its strong adsorption, rapid precipitation and
immobilisation into unavailable forms including organic
moieties. As soils are complex and diverse chemical,
biochemical and biological systems, strategies to access
recalcitrant soil P are often inefficient, case specific and
inconsistently applicable in different soils. Finding a
near-universal or at least widely applicable solution to
the inefficiency in agricultural P use by plants is an
important unsolved problem that has been under investigation
for more than half a century.
Scope : In this paper we critically review the strategies
proposed for the remobilization of recalcitrant soil phosphorus for crops and pastures worldwide. We have
additionally performed a meta-analysis of available soil
31P–NMR data to establish the potential agronomic
value of different stored P forms in agricultural soils.
Conclusions : Soil inorganic P stocks accounted on average
for 1006 ± 115 kg ha−1 (57 ± 7%), while the
monoester P pool accounted for 587 ± 32 kg ha−1
(33 ± 2%), indicating the huge potential for the future
agronomic use of the soil legacy P. New impact driven
research is needed in order to create solutions for the
sustainable management of soil P stocks.