Water, Land and People - Goulburn Broken Catchment ...

ACTIVITIES AND ACHIEVEMENTS
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• The various types of Farm Program Incentives have
been digitised to facilitate reporting and mapping;
• Created map documents to help staff easily create
spatial documents;
• Provide technical support through telephone, email,
site visits and one-on-one support;
• Provide GIS information to support project and
Landcare group activities and reporting.
Achievements and implications
Spatial Information Sciences are building capacity for
staff to use the tools to collect data in an efficient and
effective manner and give staff the confidence to create
and understand spatial data.
This project allows Shepparton Irrigation Region
Catchment Implementation Strategy support staff to
create spatial products easily, collect data, store the data,
easily access it and carry out spatial analysis of that data.
This will also improve data quality over time, as well as
enable data that might once have been seen only in table
format to be presented in more easily understood map
formats.
Feasibility and sustainability of sub-surface
drip irrigation in pasture production
Background
Ongoing water shortages and potential future reductions
in water supply highlight the need to make best use of
the available water. Sub-surface drip (SSD) irrigation can
deliver water directly to the plant rootzone and thus
reduce potential evaporation, runoff and drainage losses.
Installation of SSD on dairy farms may also benefit regional
water quality by reducing irrigation run-off. However, dairy
farmers are unlikely to invest in SSD irrigation if they
are not confident it can withstand cattle grazing and be
economically viable.
The project has established two field experiments located
on two dairy farms in northern Victoria, testing how SSD
performs on a ‘light’ and a ‘medium’ soil. The experiment
is testing SSD design (tape spacing) and management
(irrigation frequency) on pasture production and the
pathways of water and solute movement.
The three main objectives of this project are to:
• Assess the practical and economic feasibility of SSD
irrigation on dairy farms;
• Evaluate the economic, environmental and social
consequences of SSD irrigation on dairy farms, at both
the farm and catchment scales;
• Produce information about SSD irrigation on dairy
farms for irrigators, irrigation service providers, and
irrigation extension and policy programs.
Project activities
Sub-surface Drip has maintained pasture production
under grazing throughout the 2006-2007, 2007-2008 and
2008-2009 seasons. Pugging issues due to grazing have
not occurred. The dry spring of 2006 showed that SSD
can be used to germinate pasture on a medium soil, but
SSD should not be used for pasture establishment on light
soils. The results have also shown that the performance
of SSD in achieving uniform spread of water and hence
pasture growth is strongly influenced by soil structure and
water behaviour in that soil. On the medium soil, pasture
production is unaffected by tape spacing or irrigation
frequency, but on the light soil pasture production
decreased as tape spacing increased from 0.6 to 1.0 and
1.4m (see Figure below).
Results from these experiments are being used to show
how SSD would work in other situations to identify the
best combinations of system design and management for
different soils. This will ensure the technology is used for
maximum benefit. The implications for catchment level
management of water and water quality are also being
considered.
A recent desktop economic analysis showed that SSD
for pasture production could be profitable, provided
that significant improvements in pasture production and
consumption and water savings are achieved, with the
grown pasture highly valued. The investment is not wise if
only water savings will be made.
Achievements and implications
The work to date has shown that while sub-surface drip
irrigation can maintain pasture production under grazed
conditions, it will not be suitable for every dairy farm. Its
success is greatly dependant on the soil of the site. SSD
will achieve most uniform irrigation and best pasture
growth on duplex soils with low permeability subsoil.
On light soils, gravity drainage beneath the dripper tapes
allows too much downward movement of water which
prevents uniform irrigation, reduces pasture production
and leads to inefficient water use as water escapes
below the plant root-zone. From an economic viewpoint,
sufficient gains in pasture production and water savings
over conventional irrigation would be needed for it to
show a positive return on investment.