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New Zealand Journal of Agricultural Research abstracts

The fate of potassium, calcium, and magnesium in simulated urine patches on irrigated dairy pasture soil

M. S. B. EARLY
K. C. CAMERON

Department of Soil Science
Lincoln University
P. O. Box 84
Lincoln, New Zealand

P. M. FRASER

Crop & Food Research
Private Bag 4704
Christchurch, New Zealand

Abstract  A lysimeter study was carried out at Lincoln University, Canterbury, New Zealand from July 1990 to July 1991 to determine the fate of potassium (K), calcium (Ca), and magnesium (Mg) in urine patches on an irrigated dairy pasture soil (Templeton silt loam). Five undisturbed monolith lysimeters (800 mm diam. x 1200 mm depth) were extracted from an established ryegrass/white clover pasture. The lysimeters were installed in an underground lysimeter facility, where a 2 litre solution of synthetic urine, containing the equivalent of 55 g m-2 of K, was applied evenly to the surface of each lysimeter (c. 0.5 m2) to simulate a dairy cow urination event. No Ca or Mg was applied in the urine. During the following year, leachate composition and pasture yields from each lysimeter were determined.

Twenty percent (10.76 g m-2) of the urine-applied K was retained within the exchangeable fraction in the top 0-5 cm depth of soil. Total leaching losses of K during the experiment were negligible (0.99 g m-2 yr-1), and represented only 1.8% of the applied K (55 g) in the urine. Leaching from below animal urine patches was found to be a major loss pathway for soil Ca and Mg, with 7.4 and 4.9 g m-2 leached, respectively, over the duration of the experiment.

Keywords  leaching; potassium; magnesium; calcium; pasture; soil; urine; lysimeter; drainage; irrigation

New Zealand Journal of Agricultural Research, 1998, Vol. 41: 117-124

0028-8233/98/4101-0117 $7.00/0 (c) The Royal Society of New Zealand 1998

PDF file of entire paper: medium quality (653K); (scanned from paper original: notes about this process)

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