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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Soil Management and Sugarbeet Research » Research » Publications at this Location » Publication #337400
Title: Assessing edge-of-field nutrient runoff from agricultural lands in the United States: How clean is clean enough?

Author
item Harmel, Daren
item PAMPELL, REHANON - Texas Agrilife Research
item Leytem, April
item Smith, Douglas
item Haney, Richard

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2017
Publication Date: 1/8/2018
Citation: Harmel, R.D., Pampell, R.A., Leytem, A.B., Smith, D.R., Haney, R.L. 2018. Assessing edge-of-field nutrient runoff from agricultural lands in the United States: How clean is clean enough? Journal of Soil and Water Conservation. 73(1):9-23. https://doi.org/10.2489/jswc.73.1.9.
DOI: https://doi.org/10.2489/jswc.73.1.9

Interpretive Summary: Excess nutrients from numerous sources (e.g., agricultural and urban runoff, treatment plant discharge, streambank erosion) continue to adversely impact water resources in spite of improved treatment technologies and management practices. In fact, determination of cause(s) of accelerated nutrient enrichment has become a controversial and legal issue in several US regions. In these regions, edge-of-field nutrient runoff targets can support planning, management, and mitigation of the agricultural contribution. Without such targets, modeling tools and other decision aids can estimate nutrient reductions but cannot assess whether field scale losses are “acceptable” in terms of meeting downstream water quality goals. The scientific and practical issues associated with potential alternatives for establishing local/regional edge-of-field nutrient runoff targets were evaluated. “Direct comparison” alternatives (with reference site data, existing criteria/standards, and measured data compilations) were evaluated with measured data examples, and pros and cons of each were presented. In addition, “indirect assessment” alternatives (using soil test phosphorus levels, phosphorus Indices, field-scale models, or certainty programs) for assessing potential nutrient runoff were discussed. This evaluation provided valuable insight into the science and difficulties of establishing local/regional nutrient runoff targets. It also concluded that certainty programs offer the most promise in terms of improving agricultural management to achieve water quality goals; therefore, increased participation in these programs is encouraged. Similarly, agriculture, industry, and municipalities are encouraged to develop, transfer, and implement enhanced practices where needed to minimize nutrient contribution from point and nonpoint sources, acknowledging the reality that some nutrient loss is unavoidable from each natural and anthropogenic source.

Technical Abstract: Excess nutrients from numerous sources (e.g., agricultural and urban runoff, treatment plant discharge, streambank erosion) continue to adversely impact water resources in spite of improved treatment technologies and management practices. In fact, determination of cause(s) of accelerated nutrient enrichment has become a contentious and sometimes litigious issue in several US regions. In these regions, edge-of-field nutrient runoff targets can support planning, management, and mitigation of the agricultural contribution. Without such targets, modeling tools and other decision aids can estimate nutrient reductions but cannot assess whether field scale losses are “acceptable” in terms of meeting downstream water quality goals. The scientific and practical issues associated with potential alternatives for establishing local/regional edge-of-field nutrient runoff targets were evaluated. “Direct comparison” alternatives (with reference site data, existing criteria/standards, and measured data compilations) were evaluated with measured data examples, and pros and cons of each were presented. In addition, “indirect assessment” alternatives (using soil test phosphorus levels, phosphorus Indices, field-scale models, or certainty programs) for assessing potential nutrient runoff were discussed. This evaluation provided valuable insight into the science and difficulties of establishing local/regional nutrient runoff targets. It also concluded that certainty programs offer the most promise in terms of improving agricultural management to achieve water quality goals; therefore, increased participation in these programs is encouraged. Similarly, agriculture, industry, and municipalities are encouraged to develop, transfer, and implement enhanced practices where needed to minimize nutrient contribution from point and nonpoint sources, acknowledging the reality that some nutrient loss is unavoidable from each natural and anthropogenic source.