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Soil Moisture Monitoring
23 September 2021
2021 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 are required, and speedos are automatically updated.

Victorian rainfall deciles for April - August. Wimmera and Mallee received average to below rainfall in those five months but some areas of NE Victoria and Central highlands were average.

Figure 1: Growing season (April to August) rainfall deciles for Victoria

Most of the Mallee and Northern Wimmera, and parts of Central Victoria, are below the average rainfall for the growing season (up to the end of August). September is tracking on this similar path (see figure 2). Other cropping districts have received average rainfall for the past five months that has supported high crop growth. East Gippsland is above average for rainfall and moisture probes in this region show that wet conditions are still being recorded.

Victoria rainfall totals for September.

Figure 2: September month to date rainfall totals (19 September)

Regions in the north west of the state that have recorded less than 25 millimetres of rainfall have not received enough rain to meet crop demands, and have continued to deplete soil moisture. Some of these districts started the season with low soil moisture resulting in low yield potentials. Areas that have recorded more than 25 millimetres (month to date) of rain are in a good position to fulfill yield prospects. In regions where more than 50 millimetres of rain has fallen soil moisture is continuing to be banked.

Month rainfall percentages for Moisture (month to date). The Wimmera and Mallee have 20 - 80 per cent of rainfall (month to date) and is on track for below average rainfall for the month.  It has been wet in East Gippsland and average in the North East.

Figure 3. Month to date (19 September) rainfall percentages for Victoria

There are large parts of Victoria’s cropping areas that are well below average rainfall for September thus far. Ripening crops will rapidly deplete moisture reserves if below average rainfall conditions continue, with implications for crop yield.


Soil moisture monitoring sites rated by quartile moisture per cent (new product development for the Ag Vic SMM dashboard)

Figure 4. Soil moisture monitoring sites rated by quartile moisture per cent (new product development for the Ag Vic SMM dashboard)

Blue dots represent sites with above 75 per cent deep soil water storage, predominantly in Victoria’s South West, North East and Gippsland. There are areas in Central Victoria that still retain good moisture profiles for this time of year. Profiles are generally wetter in the southern areas of the Wimmera and drier in the north. Soil water in the Mallee is low to medium. Moisture values are higher in paddocks where hay was grown in 2020 than in paddocks where crops were harvested for grain.

Speedo assessments

Soil moisture measurements collected by the Agriculture Victoria monitoring network indicate a range of low to low/moderate soil moisture conditions in the Mallee and Wimmera with some better patches in those regions due to isolated storms. Southern parts of the Wimmera are moderate to high. North Central regions have depleted large volumes of moisture reserves in the past 6 weeks. North East distiricts still have medium to high deep soil moisture levels and the high yield potential crops were supported by good rain in early September.  

South West Victoria still have wet sub-soils and Gippsland have had a wet September.


Soil moisture speedos 20 September 2021

Note -  use to monitor the changes to the sites relevant to you inbetween the next reporting period.

Ag Vic SMM network site percentages. Werrimull 70%, Normanville 30%, Speed 80%, Ouyen 25%, Birchip 45%, Brim 25%, Sheep Hills 52%, Taylors Lake 68%.
Speedo soil moisture graphs
Werrimull soil moisture (30-100cm)
Werrimull Speedo, moisture currently 70%
Individual soil moisture trace from Werrimull, decreases at 30-80cm.

Werrimull stacked individual soil moisture graph – 2020/2021 view

The wheat at Werrimull continued to deplete moisture from 30 to 80 centimetres through September as rainfall was not meeting crop demands. Early August rain connected to residual soil moisture from a low yielding oaten hay crop in 2020. This crop didn’t access all the available water and there are still some traces of water from the 50 millimetre thunderstorm on 1 January.

Ouyen soil moisture (30-100cm)
Ouyen soil moisture is currently 31 per cent.
Ouyen individual soil moisture traces. Moisture was used down to 50 - 60cm have been used by the wheat in September.

Ouyen stacked individual soil moisture graph – Growing season view

The Ouyen site had some moisture improvements at 30 - 60 centimetres during winter but the wheat has depleted those reserves as rainfall didn’t meet crop water requirements. Residual moisture remains below this depth (left over from last year’s vetch hay crop) and is now being used. Paddocks where grain crops grew last year would be drier in this district (east of Ouyen).

Speed soil moisture (30-100cm)
Speed speedo showing 80%

There has been some moisture depletion by the wheat crop at Speed. This crop is late developing after a challenge to emerge, with patchy plant numbers, so biomass is low to moderate and water requirements reflective of its growth stage.

Normanville soil moisture (30-100cm)
Normanville speedo moisture currently 30%
Separate trace soil moisture graph from Normanville showing moisture being used from 30-50cm.

Normanville stacked individual soil moisture graph – 2020/2021 view

All moisture improvements at this site during winter have been consumed by the vetch crop that has been developing crop biomass for fodder production in the past month. Like many monitoring points, the moisture deficit that was generated in August was not able to be met with early September rain.

Birchip soil moisture (30-100cm)
Birchip speedos moisture currently 45%

Small deep soil moisture changes at the medium/heavy soil type at Birchip has continued but the paddock is in fallow and is an opportunity to allow moisture infiltration if rainfall is suffiecent.

Brim soil moisture (30-100cm)
Brim speedo moisture currently 25%
Separate trace soil moisture graph from Brim showing moisture being used from 30-50cm.

Brim stacked individual soil moisture graph – 2020/2021 view

Moisture conditions at the Brim soil moisture monitoring site peaked on 10 August and since then, the vetch has been using water as biomass is generated for fodder production. Almost all the moisture reserves gained in winter has been used in early spring.

Sheep Hills soil moisture (30-100cm)
Sheep Hills speedo 52 per cent
Sheep Hill individual sensors that used moisture at depths of 30-60cm during August and September.

Sheep Hills stacked individual soil moisture graph – 2020/2021 view

The crop being monitored is late developing canola but moisture requirements are increasing with stem elongation and early flowering.  All the moisture reserves built up over the winter have now been consumed and the crop is using the residual moisture from the paddock history of vetch hay last year.

Taylors Lake soil moisture (30-100cm)
Taylors Lake speedo soil moisture currently 62%

There were some good soil moisture improvements during winter with average/above average rainfall on this heavy grey vertosol soil at Taylors Lake. This paddock has gone back into pasture and  clover will have a low water requirement until biomass develops.

North Central
Coonooer Bridge soil moisture (30-100cm)
Coonooer Bridge soil moisture speedo at 47%.
Separate trace soil moisture graph from Coonooer Bridge showing moisture being used from 30-100cm.

Coonooer Bridge stacked individual soil moisture graph – 2020/2021 view

The Coonooer Bridge site has wheat currently flowering and has grown through a high water demand period where 40 per cent of the moisture was used in the last month.   Rain in early September was unable to fill the defict generated in August and it appears the wheat is quite efficient at depleting moisture at all depths, right down to one metre.

Elmore soil moisture
Summed and separate soil moisture graph from Elmore showing wet conditions from 30-70cm.
Separate trace soil moisture graph from Elmore showing moisture being used from 30-100cm.

Elmore stacked individual soil moisture graph – June to September view

The Elmore monitoring site has used 35 per cent of its soil moisture in the past month as the canola at this site progressed through stem elongation and flowering. Moisture is being consumed at all depths including down to one metre where the diurnal effects of day time moisture use can clearly be seen.

Image from Elmore SMM site 8 September with the canola in full flower.

Image of canola growing at Elmore monitoring site on 8 September.

Raywood soil moisture (30-100cm)
Raywood speedos current soil moisture 52%
Yield Prophet images from Raywood where soil moisture profiles were 90 per cent on 18 Aug and one month later the moisture was approximately 50 per cent.

Images of modelled distribution of water from the Raywood smm paddock using yield prophet.

The Agriculture Victoria SMM site at Raywood currently has a deep soil moisture profile around 50 per cent after starting the cropping season at 90 per cent. The Yield Prophet model indicates similar amounts of water in the profile and the moisture deficit continues to be used at all depths.

North East
Youanmite soil moisture (30-100cm)
Youanmite speedo moisture currently 97%
Youanmite individual sensor soil moisture graph has had soil moisture use at the shollow depths of 30 - 40 centimetres.

Youanmite stacked individual soil moisture graph – 2020/2021 view

Individual soil moisture sensor traces had capacitance values that reached their maximum value of 100 per cent in early August and again were reset to full in early September. During the past two weeks, the wheat crop has been consuming moderate amounts of shallow moisture. History has shown that wheat entering spring with a full profile, should meet high yield potentials providing all other agronomy factors are achieved.

Gippsland cropping
Gippsland (Giffard) soil moisture (30-100cm)
Gippsland speedo moisture currently 100 per cent

The Giffard West site still has a wet deep profile.

South West
Lake Bolac SMM (30-100cm)
Lk Bolac  soil moisture levels at 65 per cent

Lake Bolac has large amounts in the sub-soil moisture profile and has used about 50 per cent of the moisture in the 30 - 70 centimetre zone in the past month.

Hamilton soil moisture (30-100cm)
Hamilton soil moisture speedo 100%

Hamilton has a wet full profile.

Yalla-Y-Poora soil moisture (30-100cm)
Yella-Y-Poora individual sensor moisture graph.  Moisture levels have infiltrated down to 80cm during winter and shallow soil moisture is starting to be used.

Yella-Y-Poora stacked individual soil moisture graph – 2021 view

A new commissioned site at Yella-Y-Poora to validate an existing monitoring point reached field capacity during July with frequent rain events early in the growing season. All sensor traces 'flat lined' despite more rain in winter, indicating saturated soils. The crops are now starting to use small amounts of water at the surface.


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