In this section:
New Springs Landcare Project
Implementing water use efficiency & establishing new varieties of perennial pastures within the Upper Mt Lofty Ranges
A field day was held on Tuesday 13th October on Pasture Trials and Irrigation Scheduling (Evapotranspiration).
Final report of the project is available to download (PDF)
Dairy, beef and root crop producers in the upper Mt Lofty Ranges are now better informed on irrigation management practices, water use efficiency and perennial pastures through a project jointly developed and run by New Springs Landcare Group, SARDI and Rural Solutions SA.
Funded by Caring for our Country the project titled "Implementing water use efficiency and establishing new varieties of perennial pastures within the Upper Mt Lofty Ranges" began last year and should be completed in 2010.
Mid-winter production from lucerne at Mount Torrens (photo taken June 24, 2009)
Part 1. Dryland pasture trial results
Where: Mt Torrens, Springhead Road
Aim: To evaluate lucerne, sulla and native legume Cullen in dryland conditions.
Background.
Sulla and lucerne are both suited to similar soil types, with a pH of about 5.5-8.5, and well drained soils. Their different seasonal growth patterns (winter versus summer) make them very complimentary for feed budgeting across the farm. We recommend that they are sown in separate paddocks as mixtures between these species are unlikely to be successful.
Results
Sulla (Hedysarum coronarium) varieties Wilpena and Moonbi
In this trial the cumulative yield from Sulla reached 21 tonnes/ha in 2008 (figure 1). Sulla is a summer dormant legume, with very high winter and spring production. It is ideal for both grazing and fodder conservation.
Sulla is a new pasture legume, with 2 new varieties recently becoming available. Wilpena has an erect form, and is suitable for hay/silage production. Moonbi has a lower, semi-erect form and is marketed for grazing. However, both sulla varieties are suitable for grazing and/or hay production. Sulla has very thick hollow stems, making the use of mower conditioners preferable to reduce curing time. Observations have shown however, that the thick stems are well utilised by stock when consumed either fresh or in hay. The star in figure 1 shows the hay production yield achieved when the plant was shut up at the end of May.
Figure 1. dry weights over time for sulla production in 2008. The error bars represent the lsd for the data (the range of error for each point, which occurs in each direction of the point- positive and negative).
Sulla (2 left plots and right plot) and lucerne showing winter and early spring production (photo taken 11 September 2008).
Lucerne varieties SARDI Five and SARDI Seven
Lucerne is a summer active perennial pasture, with a deep taproot capable of accessing water from deep down in the soil profile. SARDI Five and SARDI Seven have produced 6-8 t/ha in this very dry spring (from a total of 3 cuts) from the 20th August to 15th January, with 3t/ha produced in the last 2 months. A graph showing the performance of this trial is shown below (trial sown Sept 07). The graph shows an idealised curve of production (dashed line), as well as the actual measurement of forage yield recorded for 2008 (solid line). The dashed line shows the production that would be expected under normal spring conditions.
Figure 2. Dry weights over time in 2008 for SARDI Seven lucerne. Solid line: actual yield measurement in 2008. Dashed line: idealised curve of lucerne production in year with average spring rainfall. The error bars represent the lsd for the data (the range of error for each point, which occurs in each direction of the point- positive and negative).
For more information on this trial contact Erica Marshall on 08 8303 9604, erica.marshall@sa.gov.au
Part 2. Irrigated lucerne
Two irrigated and 1 partially irrigated trial have been sown with landholders in the catchment area in 2007 and 2008. The partial irrigated trial is irrigated in late spring and autumn to extend the growing season of the pasture.
We are looking to see how well lucerne can grow in this system from stored soil moisture during the non-irrigated period (Dec-Mar).
The aim of the lucerne trials are to
- Present results on the best performing lucerne varieties on irrigated dairy farms in the Mount Lofty Ranges
- Identify persistent lucerne varieties / lines that grow well in mixtures with grasses
Figure 3. Persistence of lucerne in the first 12 months of partially irrigated trial sown on dairy farm at Mount Torrens, SA. The two lines indicate the 5% lsd, and this shows that most cultivars have established equally.
For more information on growing irrigated lucerne pastures, contact Eric Kobelt on 08 8303 9601
Part 3. Irrigation Efficiency: Amanda Schapel, PIRSA Rural Solutions
The aim is to give landholders appropriate tools to maximise the use of finite water resources.
The project builds and extends information gathered from a previous National Landcare Innovations Grant. Information gathered includes:
- Monthly bore depth and salinity readings from 35 sites with a further 23 sites having readings twice a year. Data from a number of these sites has been collected since 2005.
- Weekly soil salinity readings using a SoluSAMPLER</ä placed at two depths within the crop rootzone. Nutrient data is also being assessed at particular times in the year.
- Weekly soil moisture readings from gypsum blocks are being trialled using two different methods:
- A Gbug which is a continuous data logger programmed to collect readings every 2 hours. The gypsum blocks are monitoring three depths in the crop rootzone within, on the boundary and out of the main rootzone. The information is downloaded and sent to the landholders in a graphical format.
- A Gdot placed in the crops main rootzone provides "soil moisture at a glance". These systems are not connected to a logger and rely on the landholder to observe and record the soil moisture content.
- Irrigation events (number and duration) are recorded by the landholder.
- Soil surveys of the irrigated blocks to characterise the soil types on the property and match the irrigation application to the readily available water holding (RAW) capacity of the soil.
- More accurate water usage figures with a number of water meters to be co-funded with the landholders. Currently, water usage is calculated using duration of irrigation event multiplied by the application rate (commonly estimated) of the irrigation system.
- A local weather station has been installed to provide more accurate rainfall and evaporation data This will assist landholders who don’t have soil moisture monitoring technology, determine when is the right time to irrigate.
- Better re-use of water with an effluent recycling system being installed later this year.
Highlights of first six months
Landholders are responding well to the soil moisture information. Irrigation scheduling is being modified depending on the amount of moisture found within the main rootzone and lower in the subsoil (Figure 4).
The salinity data from the SoluSAMPLER ä is being compared to soil salinity data collected by more traditional but laborious means. This will provide meaningful benchmarks for this innovative technique. Once established, this technique will enable monitoring salinity in the crop rootzone throughout the year with minimal labour and cost.
From the soil surveys it was found that the rootzone depth for a number of pasture species extends beyond what is generally used for ‘rule of thumb’ irrigation benchmarks. This topic needs to be explored further to ensure we are providing the right advice and that irrigation applications utilise the whole crop rootzone.
The soil surveys and SoluSAMPLER ä data have identified some salinity issues. EM38 surveys are being organised for a number of properties to provide a more detailed salinity picture on a paddock scale.
Figure 4: Example of data collected from gypsum blocks using Gbug. The aim is to apply water once the soil in the top 25cm dries out to –25kPa.
Contact: Amanda Schapel, Soil and Land Management Consultant, Rural Solutions SA. 08 8389 8831, amanda.schapel@sa.gov.au
