Controlling Runoff from Subtropical Pastures Has Differential Effects on Nitrogen and Phosphorus Loads

    Authors

    P. J. Bohlen;O. R. Villapando

    Comments

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    Abbreviated Journal Title

    J. Environ. Qual.

    Keywords

    DISSOLVED ORGANIC NITROGEN; SOIL TEST PHOSPHORUS; LAKE OKEECHOBEE; ANAEROBIC CONDITIONS; CENTRAL FLORIDA; SURFACE WATERS; EUTROPHICATION; MANAGEMENT; RELEASE; FLUX; Environmental Sciences

    Abstract

    A 4-yr (2005-2008) study was conducted to evaluate the potential of pasture water management for controlling nutrient losses in surface runoff in the Northern Everglades. Two pasture water management treatments were investigated on Bahia grass (Paspalum notatum Flugge) pastures: reduced flow and unobstructed flow. The reduced flow treatment was applied to four of eight 20.23-ha pastures by installing water control structures in pasture drainage ditches with flashboards set at a predetermined height. Four other pastures received the unobstructed-flow treatment, in which surface runoff exited pastures unimpeded. Automated instruments measured runoff volume and collected surface water samples for nutrient analysis. In analyzing data for before-after treatment analysis, the 2005 results were removed because of structural failure in water control structures and the 2007 results were removed because of drought conditions. Pasture water retention significantly reduced annual total nitrogen (TN) loads, which were 11.28 kg ha(-1) and 6.28 kg ha(-1), respectively, in pastures with unobstructed and reduced flow. Total phosphorus (TP) loads were 27% lower in pastures with reduced flow than in pastures with unobstructed flow, but this difference was not statistically significant. Concentrations of available soil P were significantly greater in pastures with reduced flow. Pasture water retention appears to be an effective approach for reducing runoff volume and TN loads from cattle pastures in the Northern Everglades, but the potential to reduce TP loads may be diminished if higher water table conditions cause increased P release from soils, which could result in higher P concentration in surface runoff.

    Journal Title

    Journal of Environmental Quality

    Volume

    40

    Issue/Number

    3

    Publication Date

    1-1-2011

    Document Type

    Article

    Language

    English

    First Page

    989

    Last Page

    998

    WOS Identifier

    WOS:000289886000033

    ISSN

    0047-2425

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