• 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 1 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 to October)

The Victorian rainfall decile map for the winter crop growing season from April to the end of October shows average to below average rainfall in the cropping regions.

Figure 2. October rainfall deciles for Victoria

A large rain band went across the state on 3 October, generating decile 8 to 9 totals in the north and central Victoria and parts of central Gippsland were wettest on record with up to 200 mm.

The Wimmera with less than 25 mm and the western southwest were drier at decile 1 to 3. Recent and historical rainfall maps

Soil moisture measurements collected by the Agriculture Victoria moisture probe network and focusing on the monitoring sites of cereals and oilseeds (excluding fallow and pulses) had soil profiles rapidly deplete during spring.

Decile 1 rainfall for the 3-month period from July to September in most cropping districts (except mallee at decile 3) generated a gradual draw down of deep soil moisture reserves in winter but become more rapid in September when plant water requirements increased. 

Areas that received less than 20 mm in October continued to deplete moisture reserves.  Very deep soil moisture has been utilised and this has been observed in many moisture probe networks that are publicly available. 

The above image is the comparison of cropping site soil moisture levels from the end of September to the end of October.

The strike out line on the blue dots in October demonstrates the effect of fallow and no crop growing at sites that will have starting soil moisture in 2024.

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

All sites soil moisture percentages 31 October including annual winter crop and non-cropped paddocks and perennial pastures that will continue to deplete soil moisture.

During September, crop water requirements exceeded rainfall and the soil profile was depleted at 60 – 70 cm.  Timing of the October rainfall was fortunate and able to meet barley crop water requirements and assist grain fill.

Vetch was terminated at the end of August and no moisture was used in this paddock after this. A full profile should be carried through to next season.

Speedo shows moisture profiles are 85 % and lentils have used shallow moisture but no deep moisture below 70 cm.  Prior to the 3 October rain, lentils were rapidly depleting moisture at 50 - 60 cm.

There were 12 percentage points of moisture used in the past month, supported by <20 mm rain in early October during peak crop growth.

Rainfall didn't infiltrate down to 30 cm but briefly paused the deep soil moisture depletion. The majority of the moisture used by the lentils has been from above 60 cm.

Lentils have accessed deep moisture to 70 cm during October. Soil conditions were recently validated by soil sampling, and cores were wet from 80 cm. This moisture will be there for next season’s crop.

The high-water holding capacity soil (self-mulching clay) is still very wet to depth and is providing a large contribution to the overall summed speedo value. Canola has used moisture down to 70 cm and below this will be moisture for the following crop to utilise.

Deep soil moisture conditions are good at 87% and the paddock is in fallow to conserve the soil moisture for the 2024 crop.

High yield potential barley grown on high water holding soil has seen the crop rapidly deplete soil moisture reserves during the low decile rainfall months of September and October.

The 20 mm rain on 3 October was a valuable contributor for the end of flowering and grain fill. There has been evidence of moisture being used at one metre and below from monitored paddocks in the Wimmera this spring.

Crop lower limits on this sites data display will need to be revised as some sensors are  measuring the driest soil during the monitoring period. The barley crop is working hard to utilise the deep moisture to fill grain. Large cracks in the soil are 80 cm in depth and 7 cm wide near the probe site.

The canola crop has been depleting soil moisture reserves since early August. October rain appears to have had production benefits as it paused the depletion of the soil moisture reserves briefly.

The paddock next to the monitoring sites has been brown manured and it will be interesting to check the differences in soil moisture in autumn.

The individual sensor values are approximately the same capacitance number as prior to the rain in early October. Soil water is still available all through the profile, and this canola crop yield appears not to be moisture limited.

Image from 3 October with rain steadily falling and top of the umbrella visible. High biomass oat crop, grown on free draining soil that provides readily available water to plants and expecting a solid export oaten hay yield.

Modelled soil moisture at Elmore with the Soilwater app compared to moisture probe data. Substituted wheat in the model for the oaten hay crop but is showing similar trends. High biomass crops had large water demand requirements through August - October.

Youanmite had a near full profile in mid-August and was set up for above average yielding wheat. The crop used 50 percentage points of moisture in the past month after a yield boosting rain (100 mm) in October that effectively simulated a full irrigation event and refilled the top profile.

Over 50 % of the moisture profile was used in the month prior to the rain during the dry September.

The Giffard West site in Gippsland had a significant boost from the rain band that moved into central Gippsland in early October and persisted for days, with the site recording 150mm of rain.

East Gippsland was desperate for rain and the canola crop that was flowering at the monitoring site was not too far gone to respond.

The Lake Bolac site is showing evidence of soil moisture depletion all through the profile and 30 percentage points have been used in the past month.

The dry spring in the Southwest and the canola has used 40 percentage points in the past month, after 50 % was used in September.

Wheat grown at Yella – Y - Poora has continued to deplete soil moisture reserves at the deeper depths, as small October rain events have not increased soil moisture conditions.