Pasture

Pasture production

Pasture production is based mainly on annual ryegrass and subterranean clover pastures with a 7 month growing season (April to November). The growing season is longer in the more southerly regions than the more northern areas, usually by 4-6 weeks. Production from annual pastures ranges from 6 to 12 t DM/ha/yr depending on management and fertiliser strategies.

Net growth of annual pastures recorded on commercial dairy varies from 20-40 kg DM/ha/day (May-June), falling to 15-35 kg DM/ha/day (July-August) and increasing to either 40-70 kg DM/ha/day if grazed or 90-140 DM/ha/day if locked for hay/silage (September-October). Some 30-40% of growth occurs over a 3-4 month period from mid-April/May to mid August with most of the remainder produced over the next 2-3 months. Given sub-optimal nutrient status on some farms, growth rates can be improved by the strategic use of fertiliser.

Growth rates recorded for shires (S) or locations are presented below for 2007 (http://www.pasturesfromspace.csiro.au) . These growth rates cover annual pastures across a range of agricultural enterprises and soil nutrient status.

Perennial pastures exist in irrigation regions and summer moist areas. They are based on perennial ryegrasses and white clover, and/or paspalum and kikuyu. Pasture production from perennial based pastures ranges from 16 to 22 t DM/ha.

Annual pasture growth rates for potential new dairy areas based on a pasture/feedlot based production system are presented below.

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Irrigation Requirements

Pastures grown under flood irrigation use 10-12 ML/ha per annum. Efficiencies offered by centre pivot irrigation systems have reduced this requirement to the order of 8-9 ML/ha in the Harvey Irrigation Area. Depending on region and seasonal conditions, centre pivots require 6-9 ML/ha.

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Irrigation availability

Dams
In the Waroona-Harvey-Dardanup area water is available from an established irrigation scheme (Harvey Water). Harvey Water’s operating licence for the years 1996-2006 was a total allocation of 153,460 ML per season from the seven dams that serve this irrigation area.

Each year the Department of Water, considers the status of the supply dams and decides what percentage of Harvey Water’s licensed water allocation is available for use. Irrigators are informed of this before the season starts. Water allocations for the 2007-08 season were:

Waroona – 90%;

Harvey – 75%

Collie – 100%.

Harvey Water costs include a fixed charge of $19.11/ML and a variable charge according to water used of $22.29/ML.

Reforms have separated entitlement to water from the land title; hence water can be traded separately from the land within the co-operative. The entitlement to water can be leased for a season, or sold outright. Further information on this can be obtained from the Department of Water

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Groundwater

In some areas (e.g. Boyanup/Capel and Scott Coastal Plain) water is available from acquifers. Some of these reserves are not fully allocated and offer potential for irrigated dairy farming. Water can also be transferred from other users subject to private negotiation. Note: It is important to consult with the Department of Water before transferring water, as licence holders are required to submit a management plan for approval.

Licences are required for all artesian groundwater wells in WA with new licences issued only if the total allocation issued will not exceed the limits for the resources available. Currently there is no charge for water taken from licensed bores.

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Surface water
In proclaimed areas a license is required to take water from either a watercourse or groundwater aquifer whereas in unproclaimed areas water can be taken from watercourses without a licence so long as the flow is not “sensibly” diminished, affecting the rights of downstream users.

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