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Soil Moisture Monitoring
 
24 August 2022
2022 Issue 6
In this edition:
Introduction

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 and will represent the most recent rainfall.

Recent Soil Moisture Monitoring observations

From 22 August

Victorian rainfall deciles for June and July. Average rainfall in the majority of the cropping districts in the wimmera with some patches below average in the Mallee and North Central.

Figure 1: June and July rainfall deciles for Victoria

Average rainfall for most parts of the Wimmera. August is on track for this trend to continue (see figure 2). Below average rainfall for the Mallee, cropping areas of the North East and parts of North Central Victoria.

August rainfall percentages (month to date 22 August) for Victoria Half way for the month and all cropping districts are tracking below average for monthly August rainfall except the wimmera.

Figure 2: August rainfall percentages (month to date 22 August) for Victoria

Over two-thirds progressed for the month and the cropping districts around Horsham have received average rainfall, which has been beneficial for soil moisture increases. It has been dry in the Millewa.

July rainfall (month to date, 22 August) for Victoria A  drier start to the month in Northern and North West parts of the state. Early sown crops with less than 10 millimetres are starting to create a moisture deficit in the soil.

Figure 3. August rainfall (month to date, 22 August) for Victoria

A drier start to the month in Northern and North West parts of the state. Early sown crops with less than 10 millimetres are starting to create a moisture deficit in the soil. Mid-winter is early to create a moisture deficit but reflects crop biomass and developing yield potential at the monitoring sites.

Speedo assessments

Soil moisture measurements collected by Agriculture Victoria have shown that soil moisture profiles have remained stable over the past month, with some Mallee sites drying slightly and Wimmera sites getting wetter. Crops depleting small amounts of moisture will be due to higher water requirements, with larger biomass supporting high yield potentials.

Winter has historically been a time to build soil moisture profiles. High yield potential crops ideally have a full or near full soil moisture profile at the end of winter. 

Mallee site data indicates a range of moderate/high deep soil moisture conditions, and some areas experiencing drying of the topsoil after average to below average rainfall in the past 10 weeks.

The Wimmera is also moderate/high but conditions are wetter in the top horizon after higher rainfall totals from storms during August, and these rain events have had better infiltration. Observing positive moisture improvements at the monitoring sites during this critical month of August is ideal to promote plant growth and high yield potential.

Central Victoria and North East Victoria have high soil moisture conditions. Patchy storms have passed over the regions during August and it seems like each cloud has the possibility of depositing rain and maintaining a full or near full profile as we enter Spring. 

These are positive indicators for high yield potential and crops have had nutrition applied to meet their potential.

The South West region has deep soil moisture levels ranging from moderate to moderate/high, but this is adequate for the high rainfall zones. Seasonal outlook and conditions are excellent for yield potential.

Soil moisture speedos 22 August 2022

Note - use extensionaus.com.au/soilmoisturemonitoring to monitor the changes to the sites relevant to you in between the next reporting period and following rain events.

Soil moisture speedo values, Werrimull 98 per cent, Ouyen 58 per cent, Sheep Hills 80 per cent, Normanville 74 per cent.
Speedo soil moisture graphs
Mallee
Werrimull soil moisture (30 – 100 cm)
Werrimull Speedo, moisture currently 98%

Soil temperature at 11.9 degrees, low biomass crop at this stage and reflects the low water use during winter.

Ouyen soil moisture (30 – 100 cm)
Ouyen Speedo, moisture currently 58%
Ouyen individual soil moisture traces. Moisture has been recorded at 100 cm in winter but in the past two month has been depleted at 30 - 70 cm.

Ouyen stacked individual soil moisture graph – 2022 view

Moisture continues to be depleted from the soil at Ouyen with 45 per cent used in the past six weeks. Rainfall has not met the barley crop water demands.

Soil water has been used at many depths as the roots explored the sub-soil but it has predominately come from 40 - 60 centimetres.

Speed soil moisture (30 – 100 cm)
Speed speedo showing 100%

The Speed soil moisture monitoring site has a wet profile down to 80 centimetres (some of those zones are still saturated, above 100 per cent moisture). During winter, plant water requirements have been met by rainfall.

Normanville soil moisture (30 - 100cm)
Normanville is 74%
Images of the Normanville smm site with logger box and soil cores

Excellent wheat growth and root development at Normanville following vetch hay has set up a high yield potential. Crops with high yield potential can deplete soil water reserves in a dry winter.

For recent changes associated wth 23 August rain, please follow this link.

Wimmera
Sheep Hills soil moisture (30 – 100 cm)
Sheep Hills speedo 80 per cent.
Sheep Hills stacked separate trace soil moisture graph show moisture improvement to 60cm.

Early August rainfall that fell on a wet profile permitted soil water infiltration to 30 - 70 centimetres and provided a positive boost to the season. Deep moisture is rated as moderate with excellent conditions above that zone.  Wheat growing at this site will soon start to deplete shallow soil moisture reserves.

Please follow the link to the soil moisture monitoring dashboard to obtain the most recent changes to this change in the Wimmera.

Minyip soil moisture (30 - 100 cm)
Minyip soil moisture is 90%

The soil moisture infiltration opportunities this season at the Minyip/Bangerang site can be summarised in three periods during the months of April, June and August. This site also had moisture reserves available at the start of autumn (40 per cent).

Taylors Lake soil moisture (30 – 100 cm)
Taylors Lake speedo soil moisture currently 42%

There have been some small increases to soil moisture during winter. Last year’s crop of clover was a lower water use compared to faba beans growing this year. Please follow the link to the soil moisture monitoring dashboard to obtain the most recent changes with mid - August rain events in the Wimmera at Taylors Lake.

Birchip soil moisture (30 - 100 cm)
Birchip soil moisture is 90%
Photo of canola at Birchip
Soil core photo of wet soil at Birchip
Canola Roots at 60cm.

Conditions are wet at Birchip with this season’s rainfall meeting the crop requirements after the profile was filled last year in the fallow phase. Examination of soil cores in early August identified a strong developing root system to draw upon moisture in Spring.

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

Note - this paddock is in fallow with no crop growing over winter. Additional moisture has been banked with August rain events.

Moisture has moved down to 100 centimetres this season, but other district sites with crop growing could be drier.

Elmore soil moisture (30 – 100 cm)
Elmore soil moisture speedo is 75 per cent.
Stacked individual trace soil moisture graph showing no response to the 18mm rain on 17 July.

After a dry July where the wheat crop had started to deplete some deep soil moisture reserves, August has been wet. Interpretation of soil moisture data can be challenging, and Elmore commonly has preferential flow down the side of the probe with large rain events.

Waiting a week to analyse the impacts of 40 millimetres of rain now shows that this rain was able to infiltrate down to 50 centimetres, and not the initial spike with all the deep sensors.

Total moisture has improved by 15 per cent from 60 per cent on 10 August.

Soil water app model of plant available water compared to moisture probe showing moisture in profile to be over 3/4.

Modelled soil moisture at Elmore with the soilwater app compared to moisture probe data, indicates similar line trend changes associated with rainfall, and now moisture changes with the developing biomass of the wheat crop.

The two screen shots from the soilwater app model are from 19 July and current conditions.

They reflect the mid profile moisture that was being used by the wheat crop. Conditions are now wet after frequent rain events.

North East
Youanmite soil moisture (30 – 100 cm)
Youanmite speedo moisture currently 100%

The drier conditions of the past two month have just slightly dried the top horizon. Vetch, which is traditionally a low water user in winter compared to cereals, is growing in this paddock.

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

The Giffard West site in Gippsland confirmed a solid start to the season with autumn breaking in early April. The soil has remained in a wet state for the past five months.

South West
Lake Bolac SMM (30 – 100 cm)
Lk Bolac soil moisture levels at 27 per cent

Soil moisture conditions are ideal at Lake Bolac with a wet top horizon, and gradually building a moisture profile where we have previously observed strong plant uptake during spring.

The Lake Bolac site is coming from the driest base of all the monitoring network last year, and is still dry below 80 centimetres. But there is good moisture above that level for a high rainfall zone, with a good buffer against spring waterlogging with further rainfall.

Please follow the link to the soil moisture monitoring dashboard to obtain the most recent changes with late August rain events.

Hamilton SMM (30 – 100 cm)
Hamilton speedo is 100 per cent.

Rain on 31 May had significant infiltration down to 100 centimetres and was further topped up in early June to create a full profile on the raised beds at Hamilton. There is no crop growing at this site yet as it will be spring-sown with chick peas.

 
 

Privacy | Email: dale.boyd@agriculture.vic.gov.au

 
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