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This article in JEQ

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

    * Corresponding author(s): richard.mcdowell@agresearch.co.nz


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

  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.