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Journal of Environmental Quality Abstract - Landscape and Watershed Processes

The Effects of Soil Carbon on Phosphorus and Sediment Loss from Soil Trays by Overland Flow


This article in JEQ

  1. Vol. 32 No. 1, p. 207-214
    Received: Feb 19, 2002

    * Corresponding author(s): richard.mcdowell@agresearch.co.nz
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  1. R. W. McDowell *a and
  2. A. N. Sharpleyb
  1. a AgResearch Ltd., Invermay Agricultural Centre, Private Bag 50034, Mosgiel, New Zealand
    b Pasture Systems and Watershed Management Research Unit, Curtin Road, University Park, PA 16802-3702


Soil chemical constituents influence soil structure and erosion potential. We investigated manure and inorganic fertilizer applications on soil chemistry (carbon [C] quality and exchangeable cations), aggregation, and phosphorus (P) loss in overland flow. Surface samples (0–5 cm) of a Hagerstown (fine, mixed, semiactive, mesic Typic Hapludalf) soil, to which either dairy or poultry manure or triple superphosphate had been applied (0–200 kg P ha−1 yr−1 for 5 yr), were packed in boxes (1 m long, 0.15 m wide, and 0.10 m deep) to field bulk density (1.2 g cm−3). Rainfall was applied (65 mm h−1), overland flow collected, and sediment and P loss determined. All amendments increased Mehlich 3–extractable P (19–177 mg kg−1) and exchangeable Ca (4.2–11.5 cmol kg−1) compared with untreated soil. For all treatments, sediment transport was inversely related to the degree of soil aggregation (determined as ratio of dispersed and undispersed clay; r = 0.51), exchangeable Ca (r = 0.59), and hydrolyzable carbohydrate (r = 0.62). The loss of particulate P and total P in overland flow from soil treated with up to 50 kg P ha−1 dairy manure (9.9 mg particulate phosphorus [PP], 15.1 mg total phosphorus [TP]) was lower than untreated soil (13.3 mg PP, 18.1 mg TP), due to increased aggregation and decreased surface soil slaking attributed to added C in manure. Manure application at low rates (<50 kg P ha−1) imparts physical benefits to surface soil, which decrease P loss potential. However, at greater application rates, P transport is appreciably greater (26.9 mg PP, 29.5 mg TP) than from untreated soil (13.3 mg PP, 18.1 mg TP).

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Copyright © 2003. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.32:207–214.