In this newsletter we have provided a snapshot across the state of soil moisture. For new readers, you can check soil moisture and temperature for many Victorian pastures (and crops) at Agriculture Victoria’s soil moisture monitoring website.

Soil moisture is variable across the state. Some sites have full profiles but others are yet to get wet, including getting moisture to depth.

Soil temperatures are behaving nearly the opposite to last year as they have generally been increasing after a bout of frosts to very mild temperatures currently. Some farmers share their comments on the season, as it has been and plans for the spring ahead.

A full soil profile at the begining of spring provides some certainty of spring growth. This was explored in an Enhanced Producer Demonstration reported on previously. As a follow up, 2 sites have been used to look at predictions for spring pasture growth based on current soil moisture and several weather scenarios.

Compiled by Raquel Waller, Jane Court, Dale Boyd 

The 'soil cores' on the map represent soil moisture at 0-80cm depth on 21 August 2024. Many of the moisture probes shown have good to adequate soil water for plant growth, however some are still very dry.

The shading on the map indicates the west of the state has below average soil moisture average soil moisture, 0 - 100 cm, as estimated by the Australian Water Outlook, Bureau of Meteorology, 20 August 2024. While seasonal conditions are far from ideal, it is good to see the soil probe data generally matches the soil moisture map.

Notably, the south west and north east are particularly dry and have been all year. The crop site near Hamilton has been included since we wanted to reflect conditions in that area and we do not have a soil probe under pasture in that area.

Host farmer of the Hamilton crop soil moisture probe, Brent Herrman, said paddock had been 'showing a moisture status like a perennial pasture' with volunteer canola growing over summer which fed his sheep so he didn’t spray it out until autumn. 

Canola used deep soil water through January, and there was no plant available moisture at the start of autumn. Germinating rains allowed winter wheat to establish in during April, however deeper water infiltration only started in July, Brent has another probe that is on wheat stubble that had summer weed control and has a better moisture profile.

Michelle McClure, Southern Farming Systems, has also observed reasonable soil moisture under crops due to moisture being conserved over summer while pastures continue attempting to grow. Plant available water before the rain this week was 83-94% under crops in southwestern Victoria (Michelle McClure, Southern Farming Systems, 14 Aug 2024).

This chart shows the soil temperature in August of this year and last year. Early in August, most sites were cooler than last year. By mid August soil temperature had risen to similar or higher soil temperature than last year.

Clem Sturmfels, Agriculture Victoria 

With an extended period of below average rainfall, and spring around the corner, the lack of runoff into farm dams is looming as a significant issue for farmers in southwest Victoria.

Saturated soils are needed to generate runoff. The only exception is where dams are located below a road or rocky hilltop. While high intensity rainfall or thunderstorms can quickly fill dams, they pose a pollution risk and shouldn’t be relied on in a dry year.

Getting soils to the point of saturation and generating runoff at this time of the year may be challenging given the rapid growth of crops and pastures and increasing rates of evaporation. Above average or high intensity rainfall will be needed to fill dams this season.

Farmers are advised to closely monitor their soil moisture and dam water levels over coming months to ensure water availability is included in future management decisions.

While soil moisture probes can be a good guide to general conditions in your area, it is also important to check conditions closer to home. Where you can drive safely can be a good guide to soil moisture. A more detailed assessment can be made using a post hole auger or by driving a crowbar or steel probe into the ground.

Carting water for your core stock can be an option for a short period but is not practical in the longer term. Few farmers have the equipment to cart water efficiently and accessing a contractor can be difficult in a dry year. You need tanks and troughs to make carting worthwhile. Carting water to dams is wasteful and is not recommended.

For more information, including how much water is left in your dam, visit the Agriculture Victoria website.

Map showing runoff-to-date in August 2024 (source Australian Water Outlook, Bureau of Meteorology, 23 August 2024)

Comments from Robert Cooper, Manager Barton Station

• Daily pasture growth rates currently are around 20 to 25 kg/ha
• With the dry profile, seasonal pasture growth is very determinable on rainfall quantities and the timing of those events. 
• We will be living from hand to mouth until we have a substantial rainfall event
• Clover is still germinating this late in the season
• Optimistically we are 3 x 35mm rainfall events from having an average grass growing season considering our poor autumn.

See pasture predictions below

Joe Druce, Baynton

It has been a tough winter given the late and below average autumn with minimal early growth. When we got the rain it was too cold for growth and led to a run of big frosts. However, as a result of the extended growing season in January the ewes were in good condition and so we fed right up until lambing to maintain their condition score. Conditions for lambing, although short on feed, were great due to lack of cold days - rain and wind.  FOO across the farm now is only about 600-700 kgDM/ha but the rain we are getting now should set us up for spring. Clover percentage is excellent going into spring so good quality although short.

We will sow some brassicas in spring for lambs and some phalaris. We spread urea on some ryegrass paddocks just before the rain in the hope to get some quick feed to wean lambs onto in spring. We will look to wean lambs early in order to give the ewes adequate recovery time prior to next year given the ewes have suffered through lambing.

Water was a concern if we didn’t get good rain as some dams are only half full, but water is starting to run indicating we will start to get runoff with more spring rain. Hopefully a good spring ahead to make up for a drier autumn-winter!

See pasture predictions below.

Barry Newcomen, Ensay, East Gippsland

The severe frosts have reduced quality and quantity of the standing feed. Winter has been tough with a lot of feeding in the district. Luckily we had higher than usual amount of feed stored heading into winter but it has gone. Feed coming into the area has become more expensive.

The season is looking promising heading into spring but we need more rain in this area. There has been some winter rainfall but not enough to fill the soil profile unlike other areas in East Gippsland.

If spring is dry we will be looking at cutting back on numbers and early weaning to reduce the amount of feeding required. The pastures are wanting to grow with the warmer, sunnier weather we have had over the last few weeks.

Dams were full after good summer rainfall and a local flood event but they are dropping and stock water will be a concern heading into summer if spring is dry.

Soil moisture in spring is sometimes used to make a prediction of the spring pasture growth ahead. We included the Moyston site last year that showed their chances of an average or above spring was very poor given the soil moisture and climate predictions. This generally played out until some well above average rains fell close to Christmas which provided some late growth.

The Moyston probe site is yet again not fully wet, so an early indication has been made given average rain (50 decile) or above or below (as 30 and 70 decile respectively).  As a contrast, the Baynton site also is shown, as a site starting with a full profile. Pasture growth is given as kilograms of dry matter per day and long term pasture growth for each site is included as estimated between 1981 and 2023.

At the Baynton site, the predictions indicate, not surprisingly, that with average spring rains (50 decile) the area would expect an average spring. However, even with a 30 decile season, the spring growth could still be reasonable given the current higher than average growth rates, but cuts out early in November.

As a contrast at Moyston, given the lower starting moisture, below average rains ahead could lead to another very ordinary spring. Good spring rains are required. Climate predictions are leaning towards neutral or wetter conditions. If this is the case, the area could still experience a reasonable or good spring.

The soil moisture monitoring website shows data from Agriculture Victoria soil moisture probe sites as well as a number from other organisations including the Gecko Clan and Perennial Pasture Systems group and Gippsland Agricultural Group.

Both soil moisture and temperature are measured at each site with sensors to depth (recorded hourly and uploaded from the field with the telemetry unit).

The website also provides additional site information on the soil characteristics and plant species.

The new dashboard allows easier and quicker access with an improved search function.

This allows farmers to distinguish between crop types being monitored, pasture and soil types and location rainfall, all of which influence soil moisture data.

There is also a Victorian seasonal outlook for 1 – 3 months and extended into spring/summer.

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