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United States Department of Agriculture

Agricultural Research Service

Title: How does the First Year Tilling a Long-Term No-Tillage Field Impact Soluble Nutrient Losses in Runoff?

Authors
item Smith, Douglas
item Pappas, Elizabeth
item Huang, Chi Hua
item Heathman, Gary

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 27, 2006
Publication Date: September 20, 2007
Repository URL: http://hdl.handle.net/10113/5846
Citation: Smith, D.R., Pappas, E.A., Huang, C., Heathman, G.C. 2007. How does the First Year Tilling a Long-Term No-Tillage Field Impact Soluble Nutrient Losses in Runoff?. Soil and Tillage Research. 95:11-18.

Interpretive Summary: Agriculture has been identified as a contributor to water quality problems, such as eutrophication and hypoxia in the Gulf of Mexico. Fields under long-term no-till may have accumulated a large amount of nutrients near the surface, hence a greater potential for transport by runoff during rainfall events. The objectives of this study were to evaluate nitrogen (N) and phosphorus (P) losses from no-till management and after the first tillage operation of a long-term no-till field. Rainfall simulations occurred before and after fertilization with urea and triple superphosphate. Runoff volumes and nutrient concentrations were greater from the no-till field than the tilled field before and after fertilization. Varying rainfall intensity from 1 to 4 inches/hr resulted in lower nutrient concentrations during periods of higher intensity, a product of dilution from increased runoff volumes. Fertilization resulted in a ten fold increase in ammonium concentration and a one hundred fold increase in dissolved P concentration. Due to greater volumes of runoff and concentrations, ammonium loads were 150% and almost 400% greater from no-till plots before and after fertilization, while dissolved P loads were ten times greater before fertilization and 175% greater following fertilization from the no-till plots. It is typically difficult to manage land to minimize P and N losses simultaneously; however, it appears that the tillage following long-term no-till increased infiltration, which in turn resulted in lowering the risk on nutrient transport to surface water. The impact of this research is to identify a practice that could reduce the negative impacts of no-till crop production.

Technical Abstract: Water quality problems, such as eutrophication and the hypoxic zone in the Gulf of Mexico, have been blamed on nutrient losses from agriculture in the Midwestern United States. It is often difficult for producers to manage land to minimize losses of all possible contaminants and still maintain a profitable level of production. The objectives of this study were to evaluate nitrogen and phosphorus losses from no-till management and after the first tillage operation of a long-term no-till field. Variable intensity rainfall simulations occurred before and after fertilization with urea and triple superphosphate. Runoff volumes and nutrient (NH4-N, NO3-N and dissolved P) concentrations were greater from the no-till field than the tilled field before and after fertilization. Varying rainfall intensity from 25 to 100 mm hr-1 resulted in lower nutrient concentrations during period of higher intensity, a product of dilution from increased runoff volumes. Fertilization resulted in an order of magnitude increase in NH4-N concentrations and two orders of magnitude increase in dissolved P concentrations. Due to greater volumes of runoff and concentrations, NH4-N loads were 150% and almost 400% greater from no-till plots before and after fertilization, while dissolved P loads were an order of magnitude greater before fertilization and 175% greater following fertilization from the no-till plots. It is typically difficult to manage land to minimize P and N losses simultaneously, however, it appears that the tillage following long-term no-till increased infiltration, which in turn resulted in lowering the risk on nutrient transport to surface water.

Last Modified: 10/21/2014
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