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September 2026 – Issue 4
Introduction
Tracking Soil Moisture Across Victoria’s Cropping Regions
The soil moisture monitoring (SMM) project is Victoria’s longest-running moisture monitoring network, supported by more than 16 years of data. Underground probes provide calibrated, real-time soil water data for Victorian farmers. During this period, the network has captured 5 wet, 4 average and 7 below-average annual rainfall decile years, highlighting the seasonal variability faced by cropping farmers. A dashboard to measure the effects of climate change is part of the tool kit used by the grains industry.
Original sites measure soil water content at a single reference point within a paddock, from 30 cm to 1 metre deep. Recently commissioned sites measure to a greater depth, from 20 cm to 130 cm.
Locations of Agriculture Victoria soil moisture monitoring sites
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.
Weather and soil moisture monitoring observations
Rainfall has been average to wetter over much of Victoria for winter (June to August) but Gippsland has been drier, recording rainfall being average to decile 1.
Rainfall in the 50–100 mm range across large areas of the cropping district in August generated above-average rainfall deciles and boosted soil moisture profiles back to 75–100 per cent. As a result, this allows the region to enter spring with high confidence that deep moisture reserves are in place to support critical crop stages, including flowering.
August rainfall was above average across much of Victoria’s grain-growing regions, while the southwest and Gippsland were average to drier, with some districts in those regions receiving less than 50 mm.
Speedo assessments
Pictured above: soil moisture measurements displayed on the Agriculture Victoria dashboard.
Pasture sites
Most monitoring sites are dominated by perennial pasture species that will convert rainfall into plant growth, and the southwest sites have responded positively to winter rainfall. Soils have recharged, with rainfall exceeding plant water requirements. East Gippsland pasture sites are not yet fully wet, with probe locations still dry at depth.
Cropping sites
July rainfall was average to above average, and August rainfall was above average across much of Victoria, falling on soils that were already wet. This has created some waterlogging in low-lying areas of paddocks, but free-draining soils and better soil types have continued to bank deep soil water reserves below one metre and build above-average yield potential. Paddock trafficability has been tested for herbicide and fungicide applications. The monitoring site at Gippsland (Giffard West) remains dry, but rainfall improved in August after a dry four months prior.
Cropping regions are well ahead of the usual development schedule, with biomass levels reflecting above-average growth. There were some indications of early and shallow moisture depletion in July, but those losses were regained during August. Some sites have moisture graph trend lines very similar to 2017, when despite a dry September, cereal crops were able to finish on deep moisture reserves.
Based on past observations, cereal crops have depleted full moisture profiles in 6 weeks with limited spring supporting rain. Yield range was 4-4.5t/ha wheat for these examples (4t/ha in the Normanville example above) and access to moisture got tight during grain fill which took off some yield. Some moisture graphs look very similar to 2017 with characteristics of:
- carry over/good starting soil moisture,
- early emergence and solid connection of new season moisture and deeper reserves
- and top up late August.
In years like 2017, root systems were able to extract high levels of soil moisture at all depths (down to 1 metre). Inspection of root systems in early September should find active roots down to 80-100cm and beyond in better soil types. Restricted root depth in soils with sub soil constraints and waterlogged area.
Soil moisture speedos 1 September 2026
Note – use extensionaus.com.au/soilmoisturemonitoring to activate your preferred reference monitoring location soil moisture percentage.
The extensionAus SMM dashboard map provides the option to select crop or grazing sites.
This is a map of all sites soil moisture percentages on 1 September including annual winter crop and non-cropped paddocks and perennial pastures.
Cropping sites are reviewed in more detail in the sections below. Review the individual sites by clicking on the site's title to see the latest effects of rain in early September.
Crop Density
The Crop Plant Density tool is a simple method for calculating key crop metrics from crop observations in the paddock. The formula remains the same whether you are calculating plants or tillers, so the opportunity to understand crop biomass can be identified by entering tiller counts into the relevant sections. Knowing plant numbers and tracking tiller development can show potential yield and also provide guidance on grain yield. Find the crop density calculator on the soil moisture dashboard and save it to your smartphone home screen to help determine crop biomass with paddock counts. https://extensionaus.com.au/soilmoisturemonitoring/estimating-crop-plant-density/
Crop yield potential
Late September is the ideal time to initiate crop yield estimations and support farmers with finalising crop protection insurance. Tillers can be assessed, and early indications of head size can be made. Tillers can be reviewed in October to determine the number that progressed to successfully develop heads. The barley in this photo (above) has 13 grains on both sides, so the half-head count is 13. This half-head grain count is repeated six times across the paddock to gain a good representation of the stems that were counted and the heads they are supporting. Find the cereal crop yield calculator on the soil moisture dashboard and save it to your smartphone home page.extensionaus.com.au
Mallee
August rainfall in the Millewa was average. Shallow soil moisture that was used in July reflecting above average yield potential with the barley, was partially replenished by rainfall in August. By the end of the month, rainfall was meeting crop water requirements.
Barley growing at this site was likely to be one of the first monitoring points to draw down water reserves. All three sources of information form evidence that soil moisture is starting to be depleted as plant growth requirements exceeds rainfall. Soil probes, models from Yield Prophet, and the SoilWater app all indicate moisture losses, but there is still “plenty in the bank.”
Full soil moisture profiles at both Speed and Normanville.
Wimmera
There is evidence that moisture reserves are starting to be used at Birchip. The soil water model showed early moisture use by the crop at Birchip, but the moisture probe didn’t detect this. Evidence of a good boost in moisture in August.
The Brim soil moisture monitoring site is showing a near-full soil moisture profile. Yield Prophet modelling indicates a full soil water profile to 70 cm, with small moisture deficits below this depth. Rooting depth is estimated to be greater than 70 cm.
Deep soil moisture levels have continued to increase at the Wimmera sites of Sheep Hills and Taylors Lake. Compared with this time last year, they are 45% and 20% wetter, respectively.
The Minyip monitoring site shows that deep water infiltration has continued to 120 cm, filling the soil profile to 100% capacity. Compared with this time last year, it is 20% wetter.
North Central
At Coonooer Bridge, south of Charlton, chemical fallow conditions and decile 10 August rainfall have driven strong infiltration to 1 metre and beyond, with low-lying areas becoming waterlogged. The SoilWater model, simulating the water use of a wheat crop, still shows high levels of soil moisture.
The Raywood soil moisture monitoring site began the season with a near-full profile after 170 mm of rainfall in early March. Decile 10 rainfall in June and August followed. The probe shows 100% soil water, and Yield Prophet modelling indicates a full profile beyond 100 cm, with a root system developing down to 1.2 metres. Low-lying areas across the district are waterlogged due to runoff from higher ground. The site is 42% wetter than at the same time last year.
Moisture probe is currently offline, and both the crop and soil moisture models indicate strong deep soil moisture levels. This was validated with soil cores, which showed a volumetric percentage of 29% throughout the profile after oven drying, along with evidence of root systems well below 1 meter.
A volumetric percentage of 29% throughout the profile (after oven drying) and a soil type ranging from loam to sandy clay loam is at the drained upper limit and converts to 150 mm plant available water in the soil core taken down to 1 metre.
At Serpentine, soil moisture levels are 47% higher than this time last year, and at 100% plant available water, this paddock and others in the district have now been wet since early August.
Northeast
For the Youanmite district, soil moisture probes, Yield Prophet modelling, and the SoilWater app all indicate high soil moisture levels. Shallow soil moisture, which was depleted in late July due to the high biomass of the faba beans, was partially replenished by decile 10 rainfall in August.
Caniambo is 38% wetter than it was at this time last year. Significant moisture improvements occurred during early July, with water infiltration reaching 90 cm. Canola grew through the peak water-use period of stem elongation during August, when rainfall met the plant’s water demands. Despite 72 mm of rain, there were no significant moisture improvements.
Gippsland cropping
East Gippsland remains dry, with many monitoring points on the dashboard ranging from 15% to 45%. There were some moisture improvements in early August, the first in four months (see the black line on the graph — a flat line means no moisture use or gains through winter, which is unusual). This leaves the district highly reliant on spring rains, or the season will be short.
South west
The canola used some moisture reserves in early August as it reached peak water demand, but the site was boosted by rainfall on 19 August. The crop is again showing that rainfall is not matching plant water demand in early September.
The Willaura site is close to a full profile, but it has a moderate-to-low water use crop of vetch which will now increase water demand with spring growth. Soil moisture also increased in the second half of August.
The SoilWater app outputs show similar moisture status this growing season at the south west sites of Lake Bolac and Willaura, with some recent weather not meeting crop water requirements and leading to a depletion of soil reserves. Conditions are tracking close to average for this time of year and are significantly better than at the same time last year, as shown by the thin line.
Yalla-Y-Poora is 33% wetter than this time last year and has a good level of moisture in reserve heading into spring.
This newsletter is distributed by the Department of Energy, Environment and Climate Action.
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