Consistency of the Threshold Phosphorus Saturation Ratio across a Wide Geographic Range of Acid Soil

Phosphorus saturation ratio#acid mineral soils#United States# Agrosystems, Geosciences & Environment# doi:10.2134/age2018.08.0028

Biswanath Dari, Aberdeen R&E Center, Univ. of Idaho, Aberdeen, ID

Vimala Nair & Willie Harris, Univ. of Florida, Gainesville, FL

Andrew Sharpley, Univ. of Arkansas, Fayetteville, AR

Peter Kleinman, USDA-ARS Pasture Systems & Watershed Manage. Res. Unit, PA

Dorcas Franklin, Univ. of Georgia, Athens, GA 30602.

The water-soluble P extracted from these soils can be predicted from soil P storage capacity (SPSC) using an equation originally developed in the southeastern coastal plain of the United States. Phosphorus concentrations in runoff correlated strongly with the SPSC values of soils that were the source of the runoff. The PSR, M1-P, and M3-P also related closely with runoff P concentrations.

We have (i) documented the consistency of the threshold PSR for a wide geographic range of acid soils, (ii) determine applicability of a SPSC vs. water-soluble P predictive equation to soils from various regions, and (iii) relate SPSC with water quality parameters.

It was feasible to obtain a threshold phosphorus (P) saturation ratio of 0.1 applicable across a geographic diversity of acidic soils within the United States and Puerto Rico, as calculated using phosphorus, iron and aluminum concentrations from a standard soil test extraction (Mehlich 3).

Establish a common threshold in P saturation across a geographic diversity of soils.

Predict water-soluble P from soil P storage capacity to guide fertilizer strategies.

Relate runoff P concentration with soil P storage capacity.