Author:
Angus J. F.,Gault R. R.,Peoples M. B.,Stapper M.,van Herwaarden A. F.
Abstract
The extraction of soil water by dryland crops and pastures in south-eastern
Australia was examined in 3 studies. The first was a review of 13 published
measurements of soil water-use under wheat at several locations in southern
New South Wales. Of these, 8 showed significantly more water extracted by
crops managed with increased nitrogen supply or growing after a break crop.
The mean additional soil water extraction in response to break crops was 31 mm
and to additional N was 11 mm.
The second study used the SIMTAG model to simulate growth and water-use by
wheat in relation to crop management at Wagga Wagga. The model was set up to
simulate crops that produced either average district yields or the potential
yields achievable with good management. When simulated over 50 years of
weather data, the combined water loss as drainage and runoff was predicted to
be 67 mm/year for poorly managed crops and 37 mm for well-managed crops.
Water outflow was concentrated in 70% of years for the poorly managed
crops and 56% for the well-managed crops. In those years the mean
losses were estimated to be 95 mm and 66 mm, respectively.
The third study reports soil water measured twice each year during a phased
pasture–crop sequence over 6.5 years at Junee. Mean water content of the
top 2.0 m of soil under a lucerne pasture averaged 211 mm less than under a
subterranean clover-based annual pasture and 101 mm less than under
well-managed crops.
Collectively, these results suggest that lucerne pastures and improved crop
management can result in greater use of rainfall than the previous farming
systems based on annual pastures, fallows, and poorly managed crops. The
tactical use of lucerne-based pastures in sequence with well-managed crops can
help the dewatering of the soil andreduce or eliminate the risk of groundwater
recharge.
Subject
General Agricultural and Biological Sciences
Cited by
87 articles.
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