• Introduction
• Weather and soil moisture monitoring observations
• Speedo assessments – change in overall soil moisture at a particular site.
• Speedo soil moisture graphs
  • Mallee
  • Wimmera
  • North Central
  • Northeast
  • Gippsland cropping
  • Southwest

The soil moisture monitoring (SMM) 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 (cm) down to 1 metre as a reference point for a paddock.

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

No login or passwords required, and speedos are automatically updated and will represent the most recent rainfall.

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

The Victorian rainfall decile map for growing season rainfall in winter cropping regions shows a small part of north central decile 4 - 7. Gippsland is also average. The western side of the Mallee, southern Wimmera and southwest Victoria is decile 1. Remaining cropping areas in the state that includes parts of the Wimmera, Mallee and Northeast are below average.

Figure 2. July rainfall totals and rainfall deciles

Average to below average rainfall conditions provided small rainfall events during July north of the divide. There was limited opportunity to significantly build soil moisture reserves. Average to above average rainfall in Gippsland and southwest Victoria improved soil moisture profiles.

Figure 3. August rainfall totals and rainfall percentages for Victoria

Deep soil moisture levels have started to be depleted in many parts of the state during August. The topsoil horizon dried out and advancing crop development created high water demands with low rainfall. As well as being drier, August was also much warmer than the long term average.

Soil moisture measurements displayed on the Agriculture Victoria dashboard. The monitoring of cropping sites highligt the dry conditions experienced in the southwest and southern Wimmera.

Mallee, north central, Northeast and Wimmera cereal crops are using moisture with below average August rainfall. The perennial pasture sites (bottom image) are still much drier than normal.

Note - use extensionaus.com.au/soilmoisturemonitoring to activate your preferred reference monitoring location soil moisture percentage. 

All sites soil moisture percentages 26 August including annual winter crop and non-cropped paddocks and perennial pastures.

Hamilton and Yalla-Y-Poora are <25% (red dots) and Lake Bolac is 31% a result of the dry season.

The drop-down selection bar on bottom left-hand side of the map (highlighted in the red box) provides the option to either select crop or grazing sites. Cropping sites are reviewed in more detail in the sections below.

The probe was replaced in the Werrimull district in March, and still requires calibration at this new soil type. Moisture improvements that were observed in July have largely been used by the crop. This probe install was one of the drier sites during that month and this month will determine how much moisture can be extracted from the profile.

Lentils are growing at Ouyen and they are just starting to deplete moisture reserves. Higher water demand crops such as barley are likely to have lower soil moisture profiles. Ouyen has recorded <10mm for the month and a large area of the region is decile 1.

Photos of lentils from 1 August while conducting repairs to the telemetry device.

Wheat development at Speed on 1 August. Average biomass was not driving large water use during the first half of August, but depletion of the shallow moisture reserves can now be observed.

Canola has used 24% of the profile at Normanville in the last month and is showing the typical characteristics of canola being aggressive in moisture use. The crop will require two good rain events to assist flowering and pod fill to achieve yield potentials set from starting the season with a full profile.

The moisture improvements that were observed in June and July have been used in August. The barley crop will continue to deplete these reserves in the absences of rainfall to meet plant water requirements.

The moisture improvements that were observed in July have been used in August. The wheat crop will continue to deplete these reserves in the absences of rainfall to meet crop water requirements.

The wheat crop was late emerging and with delayed biomass, crop water use has not peaked like other crops listed in this report. Rainfall has meet crop water requirements.

Barley is rapidly using shallow soil moisture.  See link for September update. 

New seasons moisture is connected to the deeper reserves established from the fallow last season, but the lentil crop is late and sunset photo from a month ago on 31 July shows evidence of small plants at the time. Cereal crops in the district would have higher water use and lower soil moisture status. Below is the model of the Birchip site with the SoilWater app, assuming a wheat crop emerged in late May with a moderate/high starting soil moisture status.

Average August decile rainfall has been able to meet wheat crop water requirements.

The wheat crop is showing evidence of early moisture depletion in the shallow root zone. History shows that once this is initiated, a moisture deficit can quickly generate by high yield potential crops with limited rain.

The district has benefited from regular rain events and decile 4 -7 rainfall during August. Crop development shows high yield potential.

Modelled soil moisture at Elmore with the Soilwater app compared to moisture probe data. It shows with a estimated moderate/high plant available water at the start of April to initialise the model and the growing season moisture improvements and then the estimated spring season moisture depletion with increasing biomass.

Offline - old probe unable to be fixed and new probe installed but needs calibration. While no probe data, soil cores have been examined and posted here. Using the SoilWater app to simulate crop growth and moisture use, canola has extended a root system deep into the profile and is aggressively depleting moisture from all parts of the profile.

Good conditions at the Giffard West monitoring site with average winter rainfall. Increased crop growth is now starting to see moisture depletion from the reserves (see update).

Lake Bolac is back online and shows no moisture change since it lost contact in May as most lines match up with current moisture traces. Highlighted in yellow is the moisture that was used in February and March after early summer rain infiltrated down to 80cm.

Summed soil moisture graph of total deep soil moisture from 30cm down to 1 metre at the Hamilton site from 2014 - 2024

Hamilton has been reliable for filling during winter over the past 10 years. Starting from one of the driest soil moisture positions this autumn, rainfall infiltration has been low. The wheat crop is using water reserves when rainfall doesn’t meet crop water requirements.

Red wheat sown in early April at Yalla–Y-Poora, emerged in the second half of April and benefited from the 10 May rain event. Limited rain in the past 3 months and there have been no improvement to soil moisture reserves.  Moisture is 70% less than this time last year.