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Soil Moisture Monitoring
18 October 2021
2021 Issue 7
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 September. Wimmera and Mallee received average to patches of above average rainfall in September.  The eastern side of Victoria was wetter than average.

Figure 1: September rainfall deciles for Victoria

Decile 4 - 7 rainfall for the majority of the western half of the cropping areas in Victoria during September but there are some districts with storm cells that caused isolated large rain totals at the end of the month. The eastern side of the state was average to decile 8 - 9.

Victoria rainfall totals for the period 29 September to 5 October.

Figure 2: Rainfall totals for the week (29 September to 5 October)

Rain at this time is beneficial for crops that still have yield potential. Crops that have been moisture stressed for some time will not enjoy the full benefit but will assist grain quality.  Where the rain was required in the Northern Mallee, this district received the least and totals were less than 25 millimetres.  Great crop responses have been observed with rainfall above 25 millimetres. Areas with greater than 50 millimetres in this time period have provided crops with freely available water which will help wheat crops flower and get into early grain fill without stress.

Month rainfall percentages for Moisture (month to date). The Wimmera and North Central have 80 - 125 per cent of rainfall (month to date) and is on track for above average rainfall for the month.  It has been wet in Central Gippsland and average in the North East.

Figure 3. Month to date (14 October) rainfall percentages for Victoria

Central Victoria and parts of the Wimmera are on track for above average October rainfall which will assist crops into grain-fill. Further rain was forecast post this reporting period that could improve rainfall deciles in these areas.®ion=vc&year=2021&month=10&day=17

Speedo assessments

Soil moisture measurements collected by the Agriculture Victoria monitoring network indicate very few monitoring sites increased their deep soil moisture levels in the past three weeks despite rain in late September and early October (see figure 2).

The water deficit during mid-September was large and required 50 millimetres plus to allow water to infiltrate to the first soil moisture sensor at 30 centimetres. Rainfalls of 60 - 70 millimetres had greater impact, moving down to 30 - 50 centimetres. 

The rain was welcome in all districts and has provided some freely available water to crops, although more rain was required in the Mallee. Generally, in the Wimmera, the rain was enough to maintain crop production but not enough to bank that moisture and build reserves for the next season’s crop (at this stage).

There is still a range of low to low/moderate soil moisture conditions in the Mallee and patches of the Wimmera.  There is evidence of high yielding crops in the regions due to isolated storms during the growing season and more recently in the past three weeks. Southern parts of the Wimmera have moderate to high potential.

North Central region crops were starting to be impacted  through September with three weeks of dry weather.

Fortunately, rain received at the critical period of flowering for crops will pick up yield potential and follow up rain will provide moisture to progress through the grain-fill period.  Conditions like this last year produced exceptional grain quality.

North East districts still have medium to high deep soil moisture levels and the high yield potential crops were supported by good rain during September and early October that has provided freely available water.

South West Victoria still have wet sub-soil but high yielding crops are using water and the Gippsland monitoring site is still very wet.


Soil moisture speedos 14 October 2021

Note -  use to monitor the changes to the sites relevant to you inbetween the next reporting period and following rain events

Ag Vic SMM network site percentages. Werrimull 50%, Normanville 30%, Speed 73%, Ouyen 28%, Birchip 55%, Brim 27%, Sheep Hills 50%, Taylors Lake 48%.
Speedo soil moisture graphs
Werrimull soil moisture (30-100cm)
Werrimull Speedo, moisture currently 50%
Individual soil moisture trace from Werrimull, decreases at 30-90cm.

Werrimull stacked individual soil moisture graph – 2020/2021 view

The late sown wheat at Werrimull continued to deplete moisture from the whole profile but particularly at 70 to 80 centimetres in late September as rainfall was not meeting crop water demands. In the district early germinating barley is maturing and weeks away from harvest.

Ouyen soil moisture (30-100cm)
Ouyen soil moisture is currently 27 per cent.
Ouyen individual soil moisture traces. Moisture was used down to 60 - 70cm have been used by the wheat in September/October.

Ouyen stacked individual soil moisture graph – 2021 view

The wheat at the Ouyen monitoring site continued to deplete moisture in the profile as rainfall was not meeting crop demands in late September. Residual moisture was available after a vetch hay crop last year. Moisture was predominately obtained from 70 centimetres during winter. Rainfall in early October was not enough to infiltrate down to 30 centimetres. Paddocks where grain crops grew last year would be drier in this district (east of Ouyen).

Speed soil moisture (30-100cm)
Speed speedo showing 74%

There has been some moisture depletion by the wheat crop at Speed and 20 per cent of the moisture profile was used in the last three weeks of September.  Rainfall in early October has paused this deep moisture depletion as the crop obtains the freely available water from the top horizon of soil.

Normanville soil moisture (30-100cm)
Normanville speedo moisture currently 30%
Separate trace soil moisture graph from Normanville showing moisture was used from 30-50cm but with recent rain, nothing has registered with the moisture probe.

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 now been cut for hay. Like many monitoring points, the moisture deficit that was generated in August was not able to be met with the September and October rain. Some residual moisture has been left at depth.

Birchip soil moisture (30-100cm)
Birchip speedos moisture currently 55%

Deep soil moisture changes down to 60 centimetres at the medium/heavy soil type at Birchip. Paddock is in fallow and has an opportunity to allow greater moisture infiltration if there are further rain events.

Brim soil moisture (30-100cm)
Brim speedo moisture currently 27%

The vetch crop has been cut for hay and is now being impacted by wet conditions to cure the hay.  Rainfall has not been sufficient to increase deep soil moisture conditions because the district was dry. Rain will assist crop grain fill in the area.

Sheep Hills soil moisture (30-100cm)
Sheep Hills speedo 50 per cent.
Sheep Hill summed and stacked individual sensors that used moisture at depths of 60-70 cm during September but deep moisture use has now paused while the crop uses the water from recent rain.

Sheep Hills summed and stacked individual soil moisture graph – 2021 view

The crop being monitored is canola and moisture requirements with stem elongation and flowering increased during September.  All the moisture reserves built up over the winter were consumed during September and the crop was using residual moisture from the paddock history of vetch hay last year.  During October, rain has provided the water for the crop and up to the reporting date, 14 days of delayed deep moisture usage was observed. There is enough residual water for this crop to fill seed.

Taylors Lake soil moisture (30-100cm)
Taylors Lake speedo soil moisture currently 57%

There was 25 per cent moisture used in the past month by the clover pasture at the Taylors Lake site.

North Central
Coonooer Bridge soil moisture (30-100cm)
Coonooer Bridge soil moisture speedo at 73%.

Moisture has moved down to 50 centimetres with recent rain. Totals of over 75 millimetres have been required to infiltrate to this depth. There is enough moisture for grain fill in this district.

Elmore soil moisture
Elmore soil moisture speedo is 30 per cent.
Separate trace soil moisture graph from Elmore showing moisture being used from 30-100cm but this has pause with recent rain providing the water to the crop.

Elmore stacked individual soil moisture graph – 2021 view

The Elmore monitoring site used 70 per cent of moisture from 8 August to the end of September. Deep moisture conditions at Elmore are 30 per cent and have been relatively stable in the past two weeks due to favourable rain that has fallen on flowering crops. This canola crop has finished flowering and will use moisture for another three weeks for seed fill in the pods.

Serpentine soil moisture (30-100cm)
Serpentine speedos current soil moisture 29%

Acknowledgment to Raywood Regen Ag group for this soil moisture site report from Central Victoria while the response to recent rain at the Raywood site settles after preferential flow down the side of the probe. Almost 50 percent of moisture was used from 8 August to the end of September. Deep moisture conditions at Serpentine are 30 per cent and have been relatively stable in the past two weeks due to rain that has fallen on flowering crops. Enough moisture remains for grain fill  at this wheat crop.

Yield Prophet images from Raywood where soil moisture profiles were 90 per cent on 18 Aug and two month later the moisture was approximately 30 per cent.

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

The Yield Prophet model of conditions at the Agriculture Victoria site at Raywood currently has a soil moisture profile around 30 per cent after starting the cropping season at 90 per cent. Most of the moisture was used for a six week period from 18 August through to September but recent rain has boosted shallow moisture levels down to 50 centimetres.

North East
Youanmite soil moisture (30-100cm)
Youanmite speedo moisture currently 80%
Youanmite individual sensor soil moisture graph has had soil moisture use at the shallow depths of 30 - 50 centimetres.

Youanmite stacked individual soil moisture graph – 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. The wheat crop has been consuming moderate amounts of shallow moisture in the past month supported by frequent rainfall events.

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 and some of the deeper sensors are saturated so the total moisture in profile is 100 per cent, despite some shallow moisture starting to be used by the wheat.

South West
Lake Bolac SMM (30-100cm)
Lk Bolac  soil moisture levels at 35 per cent

Lake Bolac has used large amounts of sub-soil moisture in the past month and the 40 - 60 centimetre zone is close to wilting point.  The wheat is now using the deep soil water from the 70 - 90 centimetre area circled in red in the picture below.

Lake Bolac stacked seperate trace soil moisture graph. Moisture is being used at 70 - 90 centimetres.
Hamilton soil moisture (30-100cm)
Hamilton soil moisture speedo 62%

Canola at Hamilton has used 40 per cent from full in the past month, but the deep soil moisture reserves still exist to maintain growth for some time.

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 again during mid-October. The crops are now starting to use small amounts of water at the surface.


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