A National Assessment of the Potential Linkage between Soil, and Surface and Groundwater Concentrations of Phosphorus

Abstract

A meta-analysis of three national databases determined the potential linkage between soil and surface and groundwater enrichment with phosphorus (P). Soil P was enriched especially under dairying commensurate with an increase in cow numbers and the tonnage of P-fertilizers sold. Median P concentrations were enriched in surface waters receiving runoff from industrial and dairy land uses, and in groundwater beneath dairying especially in those aquifers with gravel or sand lithology, irrespective of groundwater redox status. After geographically pairing surface and groundwater sites to maximize the chance of connectivity, a subset of sites dominated by aquifers with gravel and sand lithology showed increasing P concentrations with as little as 10 years data. These data raise the possibility that groundwater could contribute much P to surface water if: there is good connectivity between surface and groundwater, intensive land use occurs on soils prone to leaching, and leached-P is not attenuated through aquifers. While strategies are available to mitigate P loss from intensive farming systems in the short-term, factors such as enriched soils and slow groundwater may mean that despite their use, there will be a long-term input (viz. legacy), that may sustain surface water P enrichment. To avoid poor surface water quality, management and planning may need to consider the connectivity and characteristics of P in soil-groundwater-surface water systems.(KEY TERMS: base flow; filtered reactive phosphorus; lag time; legacy; management; storm flow.)

Toward a Regional Phosphorus (Re)cycle in the US Midwest

“…Corn Belt P losses serve as primary nutrient source for marine phototrophic growth, the decay of which has led to the development of the hypoxic zone in the Gulf of Mexico (Robertson and Saad, 2013; Robertson et al, 2014). Relative to typical agronomic input rates in the Corn Belt (30–60 kg ha −1 ), relatively small losses of P (<1 to 7 kg ha −1 ) can substantially compromise water quality (McDowell et al, 2015; Rowe et al, 2016). …”

Integrating legacy soil phosphorus into sustainable nutrient management strategies for future food, bioenergy and water security

“…Sharpley et al (2013) recently provided a number of other examples where legacy P in soils and river and lake sediments is delaying the restoration of eutrophied waters. Linkages between legacy P and the enrichment of ground water are a particular concern because ground waters continually contribute nutrients to river baseflows (McDowell et al 2015).…”

Direct Exports of Phosphorus from Fertilizers Applied to Grazed Pastures

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