|VAN KEUREN, ROBERT|
Submitted to: Grassland International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/8/1997
Publication Date: N/A
Interpretive Summary: The leaching of nutrients is of increasing concern, not only for the economic loss, but also because of the potential detriment to groundwater quality. Most nutrient leaching studies have focused solely or primarily on nitrate leaching under row crops. Although some attention has been given to the influence of nitrogen fertilization of pastures on groundwater rquality, few studies have been conducted concerning other nutrients in relation to pasture management. Therefore, this multi-year study was designed to evaluate the movement of nutrients, including non-nitrogen nutrients, into groundwater when 50 lbs/acre of nitrogen was annually applied to a pasture system near Coshocton, OH. A topsoil pH of 6.0 and available phosphorus and potassium levels of 25 and 150 lbs/acre, respectively, were maintained. Concentrations of non-nitrogen nutrients were measured in water from springs draining each field in the pasture system. With this medium fertility level, it was found that the concentrations and movement of these nutrients were little impacted by this level of fertility in a pasture system. Thus, the result of this research will enable university extension and NRCS personnel to advise farmers that the potential contamination of groundwater by non-nitrogen nutrients is low with balanced, medium fertility pasture management.
Technical Abstract: The purpose of this multi-year study was to determine concentrations and transport of non-nitrogen nutrients in groundwater under a medium fertility pasture system. Rotationally grazed grass pastures received 56 kg N/ha annually as NH4NO3 for a 5-year period. A topsoil pH of 6.0 and available P and K levels of 28 and 168 kg/ha, respectively, were maintained. Concentrations of P, K, Na, Ca, Mg, and Cl were measured in water from springs draining each paddock. Nutrient concentrations did not vary greatly on a monthly basis, but there were some increases during the second 5-year period when annual N fertilizer rates were 168 kg/ha. Concentrations of K and Na changed very little; Mg changed little until the second 5 years when it increased gradually; Cl decreased slightly during the first 5 years and then increased rapidly during the second 5 years; P levels were low and decreased slightly throughout the study.