New Zealand Journal of Agricultural Research abstracts

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An investigation of localised soil heterogeneities on solute transport using a multisegement percolation system

F. STAGNITTI

School of Ecology & Environment and

Centre For Applied Dynamical Systems &

Environmental Modelling

Deakin University

P.O. Box 423

Warrnambool 3280, Australia

J. SHERWOOD
G. ALLINSON
L. EVANS
M. ALLINSON

School of Ecology & Environment
Deakin University
P.O. Box 423
Warrnambool 3280, Australia

L. LI

School of Engineering & Technology
Deakin University
Waurn Ponds
Geelong 3217, Australia

I. PHILLIPS

School of Environmental Engineering
Griffith University
Brisbane 4111, Australia

Abstract  A multisegment percolation system (MSPS) consisting of 25 individual collection wells was constructed to study the effects of localised soil heterogeneities on the transport of solutes in the vadose zone. In particular, this paper discusses the transport of water and nutrients (NO3^-, Cl^-, PO4^3-) through structurally stable, free-draining agricultural soil from Victoria, Australia. A solution of nutrients was irrigated onto the surface of a large undisturbed soil core over a 12-h period. This was followed by a continuous irrigation of distilled water at a rate which did not cause ponding for a further 18 days. During this time, the volume of leachate and the concentration of nutrients in the leachate of each well were measured. Very significant variation in drainage patterns across a small spatial scale was observed. Leaching of nitrate-nitrogen and chloride from the core occurred two days after initial application. However, less than 1% of the total applied phosphate-phosphorus leached from the soil during the 18-day experiment, indicating strong adsorption. Our experiments indicate considerable heterogeneity in water flow patterns and solute leaching on a small spatial scale. These results have significant ramifications for modelling solute transport and predicting nutrient loadings on a larger scale.

Keywords  irrigation; drainage; groundwater pollution; clay; nitrate; phosphate; chloride

New Zealand Journal of Agricultural Research, 1998, Vol. 41: 603-612

0028-8233/98/4104-0603 $7.00/0 (c) The Royal Society of New Zealand 1998

PDF file of entire paper: medium quality (1712K); (scanned from paper original: notes about this process)

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