2024 journal article
Relationships between soil test phosphorus and county‐level agricultural surplus phosphorus
Journal of Environmental Quality.
open access via doi.org (publisher)
UN Sustainable Development Goal Categories
2. Zero Hunger
(OpenAlex)
Source: ORCID
Added: September 15, 2024
Abstract National nutrient inventories provide surplus phosphorus (P) estimates derived from county‐scale mass balance calculations using P inputs from manure and fertilizer sales and P outputs from crop yield data. Although bioavailable P and surplus P are often correlated at the field scale, few studies have investigated the relationship between measured soil P concentrations of large‐scale soil testing programs and inventory‐based surplus P estimates. In this study, we assessed the relationship between national surplus P data from the NuGIS dataset and laboratory‐measured soil test phosphorus (STP) at the county scale for Arkansas, North Carolina, and Oklahoma. For optimal periods of surplus P aggregation, surplus P was positively correlated with STP based on both Pearson (Arkansas: r = 0.65, North Carolina: r = 0.45, Oklahoma: r = 0.52) and Spearman correlation coefficients (Arkansas: ρ = 0.57, North Carolina: ρ = 0.28, and Oklahoma: ρ = 0.66). Based on Pearson correlations, the optimal surplus P aggregation periods were 10, 30, and 4 years for AR, NC, and OK, respectively. On average, STP was more strongly correlated with surplus P than with individual P inventory components (fertilizer, manure, and crop removal), except in North Carolina. In Arkansas and North Carolina, manure P was positively correlated with STP, and fertilizer P was negatively correlated with STP. Altogether, results suggest that surplus P moderately correlates with STP concentrations, but aggregation period and location‐specific factors influence the strength of the relationship.