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Agronomy Journal Abstract - Phosphorus Management

Plant Availability of Phosphorus in Swine Slurry and Cattle Feedlot Manure


This article in AJ

  1. Vol. 97 No. 2, p. 542-548
    Received: May 4, 2004

    * Corresponding author(s): bwienhold1@unl.edu
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  1. Bahman Eghballa,
  2. Brian J. Wienhold *a,
  3. Bryan L. Woodburyb and
  4. Roger A. Eigenbergb
  1. a USDA-ARS, Lincoln, NE 68583
    b USDA-ARS, Clay Center, NE 68933


To utilize manure P for crop production, P release and plant availability needs to be quantified. An incubation study was conducted to determine P availability from swine (Sus scrofa) and cattle (Bos taurus) feedlot manure in three soils. Treatments for each manure included temperature (11, 18, 25, and 32°C), water regime [constant 60% water-filled pore space (WFPS) vs. four dry-down cycles of 60 to 30% WFPS], time, and soils (Catlin silt loam, Sharpsburg silty clay loam, and Valentine fine sand). In another study, synthetic P fertilizer was used to determine the fraction of P that becomes unavailable with time to compare with manure P. Time, soil, and manure application were factors that influenced soil test P and water-soluble P during incubation. At the low synthetic P fertilizer rate of 6 μg g−1, about 12 kg P ha−1, none of the applied P remained available in the Catlin soil while about one-third remained plant available in the Sharpsburg soil and two-thirds in the Valentine soil. At the high P rate, 68 mg kg−1, 38 to 83% of fertilizer P remained available in the three soils. Phosphorus availability was 60 to 100% of applied cattle manure P and 52 to 100% of swine slurry P in the three soils. Phosphorus availability in the Sharpsburg soil was 100% of P in both manure types. Phosphorus availability from manure is high, and manure can be used similar to inorganic P fertilizer in soils where P-based application is made in areas susceptible to P loss in runoff. In P-deficient soils, a P availability of 70% should be used.

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