New Zealand Journal of Agricultural Research abstracts

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Predicting soil water, tile drainage, and runoff in a mole-tile drained soil

V. O. Snow

AgResearch
Grasslands Research Centre
Private Bag 11008
Palmerston North 4442, New Zealand
val.snow@agresearch.co.nz

D. J. Houlbrooke

AgResearch
Invermay Agricultural Centre
Private Bag 50034
Mosgiel 9053, New Zealand
david.houlbrooke@agresearch.co.nz

N. I. Huth

CSIRO Sustainable Ecosystems/Agricultural Production Systems Research Unit
PO Box 102
Toowoomba QLD, 4350, Australia
neil.huth@csiro.au

Abstract   There has been considerable intensification of agriculture on mole-tile drained soils in New Zealand. Management techniques and tools are needed for predicting and understanding water and nutrient transport. While simple water balance models have been effective in estimating soil water deficit, such models cannot differentiate between the different water loss mechanisms. More complex water-transport models include the ability to predict the flow of water and nutrients through mole-tile drainage systems but none have yet been applied, or tested, under New Zealand conditions. Here we test such a model against existing data. The simulation model APSIM was used to estimate soil water extraction by pasture, slow drainage through the fragipan, mole-tile drainage, surface runoff, and evaporation from the soil surface of the Tokomaru silt loam. Soil hydraulic properties were derived from the literature. Comparison was made against previously published data on soil water deficit, tile drainage, and surface runoff. APSIM’s predictions of soil water deficit compared well against much of the available data. The exception to this was during a period of exceptionally dry soil conditions when the model predicted a lower soil water deficit than indicated by the data. There was excellent agreement between the simulated and measured drainage, as well as reasonable agreement of measured and modelled surface runoff on a cumulative basis, although there was some deviation when considered on an event basis.

Keywords   soil water balance; mole-tile drainage; surface runoff; simulation model

A06045; Online publication date 28 February 2007; Received 21 July 2006; accepted 11 December 2006

New Zealand Journal of Agricultural Research, 2007, Vol. 50: 13 - 24
0028 - 8233/07/5001 - 0013  © The Royal Society of New Zealand 2007

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