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ARS Home » Research » Publications at this Location » Publication #68726


item Owens, Lloyd
item Edwards, William

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/16/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Concentrations and transport of non-nitrogen nutrients in surface runoff and subsurface flow were determined under a high fertility pasture system during a multi-year study. Rotationally grazed grass pastures received 224 kg N/ha annually as NH4NO3 for a 5-yr period and had a legume interseeded into the grasses to be the N source during the following 8-yr period. Part tof the pastures were grazed during the summer only, and on the other pastures cattle ate fall regrowth and the hay made on that area during the summer. A topsoil pH of 6.5 - 7.0 and available P and K levels of 56 and 336 kg/ha, respectively, were maintained. Concentrations of P, K, Na, Ca, Mg, Cl, and TOC were measured in surface runoff collected with automated samplers and in water from springs draining each area. Nutrient concentrations in both surface runoff and subsurface flow were strongly influenced by the amounts of fertilizer and lime applied. The majority of P and K were transported via surface runoff, and these concentrations and transport were greater during the 8-yr period because of increased rates of fertilizer. Nutrient concentrations in subsurface flow did not vary greatly on a monthly basis but there were some increases during the span of the study. Concentrations of K and Na changed very little; Mg increased slightly; and Ca and Cl had large increases during the 13 years. Increased rates of KCl application during the 8-yr period was a primary cause for the increased Cl concentrations in the shallow groundwater. Concentrations and transport of non-nitrogen nutrients from a pasture system were little influenced by the summer vs winter management of this study or the change in N source from fertilizer to legumes. The application of non-nitrogen fertilizers and lime was the major factor of influence.