Summer 2013 - Volume 4 Issue 3
Spring Edition: Volume 4 Issue 3 September 2013
Editor: Zita Ritchie, Dairy Extension Officer/Climate Risk, Dairy Services, DEPI Warrnambool
Spring is in the air, the magpies have started swooping me on the my walk to work and you can already hear the grass growing. Aside from swooping magpies, my attention has been focused toward the Indian Ocean. Conditions in the Indian Ocean have shifted from negative to neutral over recent weeks. However, historically in years where we have had an IOD negative event it has typically resulted in average to wetter conditions for Victoria for spring. Although the neutral conditions have appeared, more favourable conditions for spring rainfall are still likely. Read the feature article about Indy to find out more.
Winter temperatures were the highest on record for Victoria and rainfall across the state was average to very much above average. Dairy regions in Gippsland recorded winter rainfall of decile 10 for most of the region largely due to heavy rainfall in June and later in August. However, the extremely dry top soil and sub soil moisture hasn't led to extreme run off or major flooding.
Dairy State Round up – Winter (June –August)
Deciles are used to rank historical rainfall data into 10 even groups which allows us to compare rainfall totals received over any interval (eg. one month or season) For example, decile 1 is the lowest 10 per cent of records for a location, which is very much below average.
Mirboo North: 10
|Region||Winter Rainfall Deciles|
|Northern - Irrigation|
The autumn break was late this year occurring around the end of the irrigation season (15th May). Rainfall over the winter period was average to above, resulting in improved sub-soil moisture levels headed into spring. Rainfall combined with slightly above average temperatures has provided good growing conditions for pasture and forage crops, with dairy farmers drawing slightly less than usual on fodder reserves. Collectively at the end of winter, irrigation storages are close to, or over 90 per cent full with substantial volumes carried over in to this season. Seasonal allocations look likely to reach 100 per cent of High Reliability Water Shares (HRWS) for the 2013-14 season.
During June pasture began to recover after a generally poor autumn. Mild temperatures during July encouraged good growth rates but high rainfall from mid-July onwards made utilisation difficult as paddocks quickly became waterlogged. Fine, warm weather at the end of August started to dry paddocks out and caused some farmers to contemplate an early cut of silage to bring pastures under control. Most farmers are optimistic of a good spring with opportunities to
|Coastal East Gippsland|
The winter started off very wet throughout the coastal east, with around half the rainfall received to date this year falling in the month of June alone and much of that fell in the third week. Due to significantly wet pastures, fodder and supplementary feeding increased in proportion as a result. Higher than average temperatures over winter has led to an earlier spring, with silage being made in some parts already. Although pastures are currently looking pretty good, the ground is drying out fast; so a good shower of rain wouldn't go astray!
|South West Victoria|
After a late autumn break in May many paddocks were slow to get going with pasture death due the dry summer. Average to above average rainfall and mild conditions in June- July assisted to boost pasture production. A very wet August resulted in some pugging and water logging but has assisted to set up favourable growth rates as we move into spring. Planning for silage and hay is currently underway and in areas where it is possible to get machinery on paddocks without causing damage many people are applying nitrogen fertiliser to assist in increasing silage and hay yields.
|Macalister Irrigation District|
With close to three quarters of MID's rain falling in June (around six times the average for that month), winter was very wet to start with. Very little rain fell in July and close to average was received in August. With daily temperatures above average as winter progressed, soil temperatures were progressively favourable for early spring pasture growth, so with a lot of grass around at the moment. However, with evapotranspiration levels taking off, it's not only the spray irrigators that need to keep a diligent eye on their soil moisture levels. Flood irrigators need to be more wary too. With a 90 per cent water allocation being announced at the start of the irrigation season, water is certainly abundant to replenish soil moisture for maintaining increasing pasture growth.
|South & West Gippsland|
Winter has been a mixed bag. Heavy early June rainfall followed by some very good winter growing conditions through July and then wet and cloudy conditions over a good portion of August. Fodder reserves have been low coming into winter, placing a larger reliance on purchased feed this winter. There is plenty of soil moisture at the end of winter, but having received more rain than West Gippsland, South Gippsland soils are very wet. Dams are full and prospects are looking good for spring production. Together with good milk prices, spring could be the start of a much needed recovery provided it is well managed.
Seasonal Climate Outlook
This model outlook has been put together by Dale Grey, editor the Fast Break Newsletter – Department of Environment and Primary Industries (DEPI) Bendigo.
Seasonal model forecasts for Victoria over the next three months
|Current outlook (August 29)||Past outlook (July 27)|
|PACIFIC OCEAN:||Neutral||PACIFIC OCEAN:||Slightly cool/ neutral|
|INDIAN OCEAN:||Slightly warm (IOD-)||INDIAN OCEAN:||Slightly warm (IOD-)|
The Southern Oscillation Index (SOI) has returned to normal values over August currently at -2.2 (5 August). This is indicative of average pressure patterns in the equatorial Pacific Ocean. A coupled situation exists between the normal ocean surface and the atmosphere.
Sea surface temperatures (SST) along the equatorial Pacific Ocean remained neutral during August (5 September NINO3.4 -0.04 C). The Coral Sea remains slightly warm and the Timor Sea has cooled slightly. A weak Indian Ocean Dipole negative (IOD-) has weakened due to a greater warming off the coast of Kenya (5 September DMI -0.17) such that is now non- existent and is now neutral.
The Southern Annular Mode (SAM) has spent most of August weakly to strongly negative resulting in enhanced frontal activity and rainfall throughout southern Victoria, but weaker in the north west of the state. Predictions for the next 14 days are closer to neutral.
The Sub Tropical Ridge (STR) of high pressure has been positioned much further north of the Great Australian Bight than normal during August, effectively allowing fronts to come through.
Modelled Climate and Ocean Predictions
Summary table of Global Climate Models with their outlook for rainfall and temperature for the next three months.
What bone is Indy going to throw us this spring?
By Zita Ritchie – Dairy Extension Officer/Climate Risk, Dairy Services, DEPI, Warrnambool
Over the last three months our attention has focused on Indy, our climate dog in the Indian Ocean, which can provide a valuable moisture source for Victoria in winter and spring. Sea surface temperature patterns for winter have been typical of a IOD negative event. A negative IOD during winter-spring can increase the chance of average to wetter conditions over southern Australia by sending a bit more tropical moisture down our way, increasing the chance of higher humidity and cloud activity.
An IOD negative is characterised by warmer than normal ocean surface water off the island of Sumatra in Indonesia and cooler than normal water off the coast of Kenya, East Africa (see picture below). The northwest cloud bands that have tracked across Australia over June and July are examples of how a negative IOD can influence rainfall in southern Australia.
Figure 1: Illustrating an Indian Ocean Dipole (IOD) negative event. The warmer sea surface temperatures (SST) off the coast off Sumatra delivers moisture to Australia from the Indian Ocean.
The last time we saw a definitive negative IOD by itself (like we've had over winter) was way back in 1992, although there were weak events in 1993 and 1996. Some of you may remember that in these years we had average to wetter conditions across the state, with floods thrown into the mix in some areas. In the spring of 2010 we also had a negative phase IOD, which was coupled with a La Niña which, as we may remember, resulted in some areas receiving their highest rainfalls on record.
Over recent weeks our Indy dog appears to have slowed down his round up, with the negative IOD completely gone and now in the neutral range. This year will still be recognised as an IOD negative year and the majority of climate models predict the IOD negative to persist or reform. For dairy regions in Victoria, IOD negative years have historically resulted in average to wetter conditions for spring. This means there is a much lower probability (or no chance) of receiving poor rainfall for spring. For example in Warrnambool, a poor spring has never occurred in an IOD negative year (based on historical records). For Echuca and Mirboo North, average to wetter conditions are more likely, with only a small statistical chance of low spring rainfall (see Figure 2).
These charts show the distribution of August-October or August-November rainfall in those years where an IOD negative event was classified by Ummenhofer et.al (2010). There have been 18 IOD negative years in a rainfall record of 120 years. As you can see, for these sites, there is much greater chance of receiving average to higher rainfall in spring when there has been an IOD negative.
In summary, given the current change to neutral conditions in the Indian Ocean , the outlook for spring rainfall is not as favourable as it was initially. However, the earlier presence of an IOD negative gives confidence the spring shouldn't be poor.
To see how the IOD affects your rainfall at a weather station near you visit Local climate tool.
To see animations of how our climate drivers affect Victoria's rainfall visit the Climate Dogs and see "Indy" in action at Climate dogs.
Making the most of spring 2013
Greg O'Brien, Dairy Services, DEPI, Ellinbank
The three month rainfall outlook for southern Australia favours average to above average rainfall and slightly warmer temperatures. While the outlook doesn't guarantee wetter conditions, it gives more confidence when planning for the months ahead.
In most dairy districts, soil moisture is reasonably good and water storage levels high due to above average rainfall for most regions over winter providing a good base heading into spring. Early spring growth will be most reliable, so make the most over this time to make you less reliant on late spring growing conditions.
Replenishing fodder reserves
High on the agenda after last year is the replenishment of silage and hay reserves, particularly for the south west and Gippsland. Forecasted average temperatures for September are likely to be favourable for pasture growth and locking up paddocks for conservation can be approached with more confidence this spring.
Boosting yields with nitrogen fertiliser is an important consideration for many. At $700 per tonne of urea spread and a 20:1 dry matter response per kilogram of nitrogen, the fertiliser cost adds about $80 per tonne of extra dry matter grown. If you add about $100 per tonne for a contractor making round bale silage, then you can boost silage reserves for about $180 per tonne. Hay making at $75 per tonne would allow hay reserves to be boosted for about $155 per tonne dry matter (note hay is about 15 per cent moisture, so the wet weight price is about $132 per tonne).
Harvesting early and looking for the opportunity to lock up additional areas later in spring will help to make the most out of spring growth. Consider a late September/early October cut and a late October cut, using a short lockup period. Pastures harvested four-five weeks after last grazing will be high in energy and protein, resulting in higher milk production when fed back. The pasture regrowth will also be much higher due to the higher tiller density (paddocks lose tillers through shading during longer lockups). The extra pasture regrowth has a two-fold benefit. It allows for more silage to be made in the second half of spring and it allows more pasture to be on hand for grazing coming into summer.
The early sowing of summer fodder crops could be a favourable option given the spring outlook as they will be establish before soil surface moisture runs out and can tap into the deeper moisture. The odds of a high yield are fairly good if the crop is sown early. The forecast doesn't go beyond three months, so there is the usual risk associated with later sown crops.
Farmers in districts that experienced a very dry summer and autumn will be looking to renovate some pastures in the near future. A spring sown crop will provide valuable summer feed and will prepare paddocks for direct drilling with pasture next autumn. To take advantage of the growing conditions in spring, sow crops early but on the same date, using a range of crops differing in their maturity dates. This will stagger feed coming on hand throughout summer, just as the cows need the extra feed.
For irrigators, good water availability will allow more flexibility in sowing times and more confidence to plant additional area to crops to fill summer feed gaps.
Farmers will be doing their own sums to compare using nitrogen to make extra silage with buying feed in. One advantage of making your own is the cost associated with transporting purchased feed to your farm. A potential advantage of purchasing is that you can purchase on the basis of its quality whereas quality of home grown fodder can sometimes be affected by delays in harvest. On the other hand, price of purchased fodder may not be known until after harvest whereas home grown fodder prices can be calculated in advance with reasonable confidence.
Look for market intelligence to help plan your feed purchasing strategy for the season, such as through the Hay and Grain report on Dairy Australia's website. If growing conditions continue favourably, supply and prices should remain reasonable. Irrigated lucerne production will be favoured by high water availability in the northern regions, increasing its availability. However the lower Australian dollar may lift the asking price for export quality hay but generally speaking, hay prices are lower behind the baler/during harvest.
In summary, make the most of early spring. Consider making extra silage using nitrogen to boost yields and short lockups to manage quality and seasonal risk. If looking to fodder crops to supply summer feed, an early sowing has less risk and is more likely to provide higher yields.
The Spring Back Page
To hear the latest seasonal update presentation from Dale Grey DEPI Bendigo and Andrew Watkins from the BoM you can stream a recording of the presentation. Click on the link to the September presentation.
Note: to view this you need Java installed and you can't save the presentation.
If you would also like a pdf copy of the presentation, please send a request to email@example.com
Warmer spring days are more likely over most of northern Australia, coastal WA, and Tasmania, while cooler days are more likely across central and northwest Victoria.
A wetter spring more likely for southeast Australia. Climate influences include a weakening negative Indian Ocean Dipole, a neutral-to-cool tropical Pacific, and locally warm sea surface temperatures.
Temporary drop in sea level due to Australian floods. Researchers have found that global sea levels dropped about 7mm in 2010-11 due to large amounts of rain falling over the Australian inland and not draining out to sea.
The behaviour of the climate driver the Indian Ocean Dipole (IOD) is of key current relevance, given it is Spring. To see how the IOD affects your rainfall at a weather station near you visit Local climate tool.
See short entertaining and informative animations (around one minute each) of a range of charismatic cattle dog cartoons (climate dogs) showing in true kelpie herding fashion how the climate drivers they represent affect Victoria's rainfall.
Of particular relevance in Spring is the climate dog "Indy" who delivers moisture from the Indian Ocean.
But don't be restricted by just clicking on this cheeky fellow, he has 4 other mates who are just as clever to watch. Climate dogs
That GREENHOUSE 2013 Conference: The Science of Climate Change (a joint Australian New Zealand event ) is happening this spring.
Tuesday 8th – Friday 11th October, 2013 at the Convention Centre in Adelaide
At this forum, the latest in climate change science, communication and policy from leading presenters from Australia and around the world. Topics include:
- Atmosphere, oceans, biosphere and the land
- Climate modelling and projections
- Climate variability and extreme events
- Impacts, adaptation and mitigation
- Communication and policy
The Greenhouse 2013 Conference is designed for researchers, representatives from all tiers of government, industry, NGOs and anyone with an interest in this topic The conference will feature a dedicated stream for representatives from Australian Natural Resource Management regions.