• Introduction
• Recent SMM observations
• Speedo assessments
• Speedo soil moisture graphs
  • Mallee
  • Wimmera
  • North Central
  • North East
  • Gippsland cropping
  • South West

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.

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

No login or passwords required, and speedos automatically updated.

Figure 1: January rainfall per cent of mean for Victoria

The blue shaded areas are districts that received 200 per cent or greater mean rainfall for January and after the dry period prior, the SMM sites in these areas had good moisture infiltration.  Generally, most of the rain influencing the mean values fell in the last week of January, so larger volumes in a short period of time had more impact than small events spaced apart.

Figure 2: January rainfall deciles for Victoria

Rainfall deciles for January are mostly average to above average but the district between Swan Hill and Ouyen is below average. If there is no further rain in the next fortnight in this district, large parts of the Mallee will have decile 2-3 summer rainfall and soil moisture values will be similar to the harvest period.  Areas of decile 10 will have "banked varying amounts of deep soil moisture" for this year’s winter crop program which is explained in this report.

Figure 3. February rainfall totals for Victoria (as at 19 February, 2021)

Rainfall was concentrated to North East Victoria and East Gippsland with rainfall on 5 February and significant infiltration observed with >50 millimetres of rain. Sites with >25 millimetres following above average January rain also had moisture move down through the wet top horizon and deeper into the soil profile.

Figure 4: AWRA modelled soil moisture

The AWRA model is a good indicator of recent rainfall and soil moisture conditions. A dropped pin location has been selected for the district of Minyip that had a positive response to the 29 January rain.

For more information go to Bureau of Meterology website landscape page  then select more information under the section - root zone soil moisture.

Soil moisture measurements collected by the Agriculture Victoria monitoring network show a wide range of conditions after recent patchy thunderstorm activity on three distinct days in the past two weeks.  Some regions have received two significant storm events with others just one, resulting in some great infiltration for areas experiencing multiple storms.

The Mallee has generally missed these storms and most monitoring sites are at similar moisture levels to harvest time last year.  If there is no rain for the remainder of the month, a large area of the Mallee will be below average rainfall for summer.  The long data set of monitoring shows that even average rainfall for summer rainfall will not build up soil moisture reserves.

The exception in the Mallee was observed at Werrimull where areas in the Millewa received 50 millimetres on 2 January and on sandy soil this water moved deep into the profile.  This event appears isolated but also in a district that has soils with low water holding capacity and not all this water will be available by sowing time.  It shows the value of having automatic rain gauges to pick up storms that are not widespread so farms can be treated as per rainfall received.

Hay paddocks have more moisture down deep compared to the cereal crops from last year.  The soft spring finish and rain in October that met crop water demands during grain fill, resulted in some of the deep moisture reserves being conserved.
Some areas of North Central and North East Victoria are in a good moisture position, as are lower parts of the Wimmera and the South West but there are some areas in these regions that have missed the storms and are still dry. 

Note - Some soil moisture monitoring speedos below have been temperature adjusted to better reflect the current moisture conditions.

Repairs to the Werrimull rain gauge were activated in time to record the early January rainfall, with more than 45 millimetres recorded.  The profile was about 50 per cent full after an oaten hay crop permitted infiltration of water down to one metre.  This is a fine sandy soil site, positioned on a mid-slope and the lowest water holding capacity of the Agriculture Victoria network. Refer to Soil Moisure Monitor on ExtensionAus for more information on site details.

The Ouyen site has slightly more moisture than this time last year but this is due to the vetch crop cut for hay on 3 September. Moisture increases in summer have been limited.

There have only been small, well-spaced rain events at the Speed monitoring site so there has been no moisture improvements this summer.  Current soil moisture levels (which are temperature compensated) are high due to no moisture use in spring with early terminated vetch.  Other cereal crops nearby would have a lower moisture status.

Oaten hay at the Normanville site used the shallow to medium depth moisture last year but the deeper moisture still exists. This is a common occurrence with hay as the season is shorter and no moisture was used in October. There have been no moisture improvements over summer at this site.

Last year the wheat crop ceased using water 11 November, with the root zone at 60 - 70 centimetres the most active prior to that date.  Some traces of moisture were still available right down through the profile.  Since then there has been no moisture increases but it still appears there are blockages with the rain gauge.

The temperature compensated speedo graph shows similar moisture values compared to last year but with a vetch hay background from last year.  Cereal crops in the district would likely be drier, particularly if January storms were < 50 millimetres.  Sites south of Sheep Hills, eg Minyip have received rainfall of >75 millimetres and these sites have had positive moisture increases (figure 4).

The temperature compensated speedo graph shows some small soil moisture increases on the grey self-mulching soil.

The Coonooer Bridge site has had the largest moisture increases at 30 - 50 centimetres but there are traces of moisture deeper than this from three distinct rain events in January.

This clay loam soil with a range of 30 - 45 per cent silt generally takes significant summer rain events to allow deep infiltration as the soil seals up.  Rain on 29 January had some positive impacts with soil moisture improvements.

Report generated from the Soilwater app (smart device app that models soil moisture conditions) with the local soil type. The Agriculture Victoria soil moisture probe is 21 per cent and the model is 20 per cent, showing similarity, particularly with minor moisture increases after the 29 January rain event.

The Agriculture Victoria SMM site at Raywood has had a 30 per cent moisture improvement in the past month and with a canola paddock history that left moisture deep in the profile after the crop had some impacts from being too wet last year.  Moisture has infiltrated down to 60 centimetres and has connected up to the residual moisture.

This is a monitoring site as part of the North Central Catchment Management Authority - Regen Ag program at Raywood and shows the influence of the recent 75 millimetres of rain that has infiltrated down to 50 centimetres with a wheat history from 2020.

Soil moisture data from the Raywood Regen Ag program with a paired site in the district of Neilborough growing wheat and barley last year.  Greater than 75 millimetres of rain 29 January shows moisture movement down to 60 centimetres and connecting to residual moisture left over from last years crops.  Ideal mineralisation opportunities exist with weed control. Thank you to the Regen Ag group for data and displaying the benefits that a network spread through a district can provide.  These sites are also shown on the SMM dashboard.

Youanmite stacked individual soil moisture graph – 2021 view

Thirty millimetres of rain at the end of January was absorbed and moisture failed to reach 30 centimetres.  Follow up rain on 5 February moved through the topsoil and penetrated down to 70 centimetres and has connected up to residual moisture left over from the canola crop last year.

Tungamah stacked individual soil moisture graph – 2021 view (source Riverine Plains)

Similar to the Ag Vic soil moisture monitoring site, rain in January wet the top horizon but had limited infiltration.  Rain on 5 February has moved moisture down to 60 centimetres and there are traces of moisture at 80 centimetres, while the >100 centimetre sensors have returned back to existing values indicating it was preferential flow.

See the Weather Plus website for more information. 

The Giffard West site has improved 35 per cent during January with rain events at the start and end of the month totalling 70 millimetres.

Lake Bolac has had moisture infiltration down to 50 centimetres with 29 January rain but it is still quite dry as other rain events have spaced apart. This was one monitoring site growing canola last year that depleted most of the soil moisture.

Hamilton is offline until repairs to rain gauge and communication system can be performed..

Yalla-Y-Poora is offline until repairs to soil moisture probe can be performed.