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Soil Moisture Monitoring
22 October 2020
2020 Issue 6
In this edition:

The soil moisture monitoring project, with the use of underground probes, provides real time soil water content data to Victoria’s farmers.

Monitoring sites have been set up in cropping regions throughout the state by Agriculture Victoria.

The sites record soil water content at one source point from 30 centimetres down to one metre as a reference point for a paddock.

Sites monitored include: Werrimul, Ouyen, Speed, Kerang, Birchip, Normanville, Lah, Bangerang, Taylors Lake, Coonooer Bridge, Raywood, Elmore, Youanmite, Hamilton, Lake Bolac, Tatyoon, and Sale.
Locations of Agriculture Victoria soil moisture monitoring sites

To access information provided in the graphs, log onto the new Agriculture Victoria soil moisture monitoring dashboard.

No login or passwords required, and speedos automatically updated.

October rainfall % of mean for Victoria. Rainfall ranges are obove 100 per cent in the wimmera and North East hills.

Figure 1: October rainfall per cent of mean for Victoria as of 20 October

The green shaded areas are districts that have already received average rain for the month of October and the darker areas indicated rainfall that are tracking above average and improving conditions for flowering and grain fill of crops.

Orange areas have missed the larger storm events and have conditions where rainfall is not meeting crop water requirements.

Month rainfall totals for September. Majority of the cropping areas of the Wimmera and Mallee had average rainfall in September but there was an area between Echuca and Swan Hill and central Gippsland that was below average.

Figure 2. September rainfall totals for Victoria

South of Horsham benefited from September storms with over 50 millimetres for the month, and there were monitoring sites that improved soil moisture conditions which is a great indicator of grain yield increases.  Crop yield potentials were maintained with 25 - 50 millimetres while the area between Echuca and Swan Hill and Gippsland that were below average for September thus crops flowering during this period would have detected triggers less favourable for full potential anthesis.

AWRA soil moisture map of Victoria from 20 October. A large portion of the state has above 40 percent soil moisture, except for the northern Wimmera, Loddon and Mallee districts.

Figure 3: AWRA modelled soil moisture

The AWRA model is a good indicator of recent rainfall and soil moisture conditions. The darker shaded areas could be generalised as being in the areas receiving greater than 50 millimetres for September (see Figure 2) and recent storms in October.

For more information go to then select more information under the section - root zone soil moisture.

Speedo assessments

Soil moisture measurements collected by the Agriculture Victoria monitoring network show a wide range of conditions but due to the fact that all the Mallee sites were in hay this year and not using water for the past 6 weeks, it is impossible to compare to this time last year (21 October 2019). The Wimmera sites have had reduced requirements for crops to draw from limited moisture reserves because of the positive spring rains. This has increased yield potentials.

North Central and North East Victoria are still in a good moisture position where recent rain has partially met crop water demands, providing better growing conditions for crops flowering and early stages of grain fill. Wheat crops will still benefit from this weekend rain.

As stated last report “most cropping scenarios based on soil moisture data will require substantial rain at some stage in September to maintain yield potential”.  In the past month this has been achieved in most districts with rain late in the month and continuing into October. Exceptions are the areas in lower part of the rainfall range 10- 25 millimetres in figure 2.

Now is the time to be assessing yield potentials by counting head numbers to determining crop density and breaking open cereal heads to assess the number of grains that have flowered and how many grains are filling per head. These assessments will determine if it was too dry in winter, or if crop recovery was achieved in August, or if the dry early September with some frosts impacted flowering.  There will be some districts that have also had the ideal season and density will be thick and grains per head well above average.


Soil moisture speedos at 20October 2020
Speedo soil moisture graphs
Werrimull soil moisture (30-100cm)
Werrimull Speedo, moisture currently 45%
Speed soil moisture (30-100cm)
Speed deep soil moisture levels currenly 85 per cent

Early sown vetch was terminated early and has conserved moisture.  Cereal crops would have a higher water requirement than this site growing vetch and moisture depletion would have occurred during spring.

Ouyen soil moisture (30-100cm)
Ouyen soil moisture is currently 25 percent.

The vetch crop at Ouyen was cut for hay on 3 September and baled end of September to make good quality hay.

Ouyen seperate trace soil moisture graph showing hay cut on September the 3rd stopped plant water use.

Ouyen individual stacked soil moisture graph – March - October view
August rain was favourable for moisture improvements and vetch development and the red vertical line clearly shows the date when the vetch was cut in early September stopping plant water use and increasing soil temperature due to more sunlight reaching the soil (temperature shown by green/yellow line)..

Normanville soil moisture (30-100cm)
Normanville speedo moisture currently 33%

Oaten hay at the Normanville site utilised the shallow to medium depth moisture but some deeper moisture from 2017 still exists. This is a common occurrence with hay as the season is shorter and no moisture used in October.

Birchip soil moisture (30-100cm)
Birchip speedos moisture currently 37%
Individual sensor trace soil moisture graph showing moisture use coming from 60-70cm in October.

Wheat crop has had higher water requirements in the past month and starting to deplete the moisture reserves particularly at 60 and 70 centimetres.  There has been a 37 per cent total moisture depletion since the start of spring.

Brim soil moisture (30-100cm)
Brim speedo moisture currently 24%
Sheep Hills soil moisture (30-100cm)
Sheep Hills speedo 50 per cent

Moisture use by the vetch crop was confined to the depths down to 70 centimetres, but ceased when cut for hay in late September.

Taylors Lake soil moisture (30-100cm)
Taylors Lake speedo soil moisture currently 20%

Grey self-mulching soil has a big tank for soil water holding capacity and it is evident the 0-30 centimetre horizon has been able to meet canola crop water requirements through winter, but with little deeper moisture in reserve, the crop has been reliant on spring rainfall which it has received.

North Central
Coonooer Bridge soil moisture (30-100cm)
Coonooer Bridge soil moisture speedo at 47%.

The Coonooer Bridge site growing canola in the Charlton district has received enough rain during the past month that has been able to meet the crop water demands and conserve some of the deep moisture.

Elmore soil moisture (30-100cm)
Elmore speedo current soil moisture 14%

Clay loam soil with a range of 30 - 45 per cent silt component has rapidly accessed soil moisture right down the profile through Spring. A high yield potential set early on the season, there was a reliance on a wet spring finish to sustain full grain number potential and grain fill.

Examples from the soil water app showing very similar conditions (modelled) to the ag vic smm probe data. Range of 14 per cent.

Report generated from the soilwater app with the soil type found locally. The Agriculture Victoria soil moisture probe is 15 per cent and the model is 14 per cent, and showing similarity, particularly with small traces of moisture at many depths down through the soil profile.

Raywood soil moisture (30-100cm)
Raywood speedos current soil moisture 56%
North East
Youanmite soil moisture (30-100cm)
Youanmite speedo moisture currently 45%
Youanmite individual sensor soil moisture graph has been saturated since May but moisture depletion from sensor 30-70cm during spring.

Youanmite stacked individual soil moisture graph – 2019/20 view
Soil moisture profile has been full since the start of May but 40 percent was used in September. 35 millimetres of rain in October has supported the canola water requirements through pod fill but a further 20 per cent was consumed.  There are other high yielding canola sites with similar soil moisture utilisation this spring (see below).

Tungamah soil moisture graph of canola use  is the same as the Ag Vic site at Youanmite.

Tungamah stacked individual soil moisture graph – 2019/20 view (source Riverine Plains) 
Similar to the Ag Vic soil moisture monitoring site, the dry July saw the canola growing at this site depleting some of the moisture reserves before the profile was reset to full with August rain.  September utilised moisture down to 70 - 80 centimetres but moisture at 80 centimetres and below appear to be still available for the next crop of wheat following this canola.

Soilwater app showing modeling of wheat water use has been higher than canola and is currently 34% moisture.

Report generated from the soilwater app with the soil type found locally. The Agriculture Victoria soil moisture probe is around 45 per cent therefore there are some similarities to the model with this case showing the crop water use of wheat.  General rule is not to rely on one source of information but to utilise other data. Soil type and crop type growing can make large differences to moisture use.

Gippsland cropping
Gippsland (Giffard) soil moisture (30-100cm)
Gippsland speedo moisture currently 50 per cent
Giffard West individual sensor soil moisture graph has observed moisture improvement in October.

South of Sale (Giffard) individual stacked soil moisture graph – 12-month view
Phoenix canola sown in early April with grazing opportunities utilised in winter. Canola was depleting water at 30-70 centimetres during September, but soil moisture boosted with 48 millimetres in October (month to date). Deep moisture from depths at 80 centimetres has had low utilisation to this point in the season.

South West
Lake Bolac Pasture SMM (30-100cm)
Lk Bolac (pasture) soil moisture levels at 77 per cent
Hamilton soil moisture (30-100cm)

Hamilton is offline until repairs to rain gauge and communication system can be performed..

Yalla-Y-Poora soil moisture (30-100cm)

Yalla-Y-Poora is offline until repairs to soil moisture probe can be performed.


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