Soil Minerals Reduce Phosphorus Availability

Association of phosphorus to soil minerals limits nutrient availability in tropical soils.

The Science

Phosphorus is a limiting nutrient in tropical soils, in part because of its tendency to associate strongly with soil minerals. Phosphorus-soil associations were measured on tropical soils from around the globe and were associated with high clay content.

The Impact

Phosphorus associates strongly with soil minerals, particularly clays, providing an important constraint on its availability to plants and microbes. Very high phosphorus concentrations were needed to confidently determine the strength of its association with soil minerals.


Very high phosphorus concentrations are needed to quantify association with soil minerals in tropical environments. Studies that aim to quantify this association typically do not use tropical soils, even though phosphorus is a key limiting nutrient in the tropics. Many studies use phosphorus concentrations that are too low to yield confidence in the parameters for the Langmuir equation that describe phosphorus attachment. This study provides specific recommendations for quantifying phosphorus associations with tropical soil minerals.

Principal Investigator(s)

Melanie Mayes
Oak Ridge National Laboratory

Related Links


This research was supported as part of the Next-Generation Ecosystem Experiments (NGEE)–Tropics project, funded by the Office of Biological and Environmental Research within the U.S. Department of Energy Office of Science.


Brenner, J., et al. “Phosphorus sorption on tropical soils with relevance to Earth system model needs.” Soil Research 57(1), 17–27 (2019). [DOI:10.1071/SR18197]