Published: 29 May 2020
Most dairy regions in Tasmania are likely to have a wetter than average start to winter. Winter is also likely to be warmer than average.
What is the weather during the first month of winter going to be like? The forecast from the Bureau of Meteorology indicates it is more likely to be wetter than average for the northern regions of Tasmania (Figure 1).
For July, there is a slightly higher chance of exceeding the median rainfall in both the north-west and north-east. For the remainder of the dairy regions in Tasmania, there is an equal chance of July being either drier or wetter (Figure 2).
The maximum temperature for June is more likely to be warmer than the long-term median maximum temperature for most the state, except for the north-west where there is an equal chance of it being either warmer or colder (Figure 3). The eastern side of King Island has small likelihood of the maximum temperature being colder than the long-term median maximum temperature (Figure 3).
The maximum temperature outlook is very similar for the month of July – it is more likely to be warmer than the long–term median maximum temperature for most of Tasmania, except the north-west.
Similar to the maximum temperature, the minimum temperature for June is more likely to be warmer in June for all of Tasmania except the northwest. In the north-west there is an equal likelihood of it being warmer or colder than median (Figure 5).
The likelihood of exceeding the median minimum temperature is slightly lower in July (compared to June) for most dairy regions in Tasmania but it is still more likely to be warmer (than colder) in July (Figure 6).
The pasture growth outlook for June and July is positive. Based on the climate forecasts, it is likely to be wetter than average, but not excessively wetter and both the minimum and maximum temperatures are likely to be above the long-term averages. This should lead to at least average or even above average pasture growth for the start of winter.
Soil temperature can be a good guide to potential pasture growth rates. Data from the Smarter Irrigation project weather stations shows soil temperature is about 10°C at Waterhouse, Elliott and Lileah but is less than 100C in the Meander district (Figure 7).
Soil temperatures this year are similar as to the same time last year at both Meander and Elliott although are trending slightly lower this season (Figures 8 & 9). Higher soil moisture levels can reduce the amount of warming in soils occurring during daylight hours. This means, even if the maximum temperature is higher this winter, soil temperature could still be lower if soil’s are wetter. This could lead to lower pasture growth rates.
Wetter soil conditions can reduce pasture utilisation as there is more trampling of pasture and more pugging damage. Having ‘wet day’ grazing strategies can minimise damage to soil and the associated reduction in pasture utilisation.
Strategies that minimise damage to soils and pasture include:
- ‘On-off’ grazing – cows are grazed on pasture for 2-4 hours and then moved to a standoff area
- Allocating two-thirds of feed for the day grazing and one-third for the night grazing
- Grazing paddocks from the back first
- Use of back fencing
- Where possible, using different gateways to enter and exit paddocks
Regardless of whether it is wetter or not this winter, it is highly likely there will be some very wet days. A grazing plan for wet days, that is well communicated to all the team and enacted when needed, will minimise pugging damage and help maintain good pasture growth rates and utilisation through the winter and into spring.
- Current climate forecasts can be accessed from the Bureau of Meteorology website. These are updated regularly.
- TIA’s Smarter Irrigation project weather stations can be accessed online from the WeatherMation website. Click on the dropdown menu and scroll down to the UNITAS weather stations.
- More information about wet soil grazing management strategies are available from Dairy Australia, Agriculture Victoria and Dr Bill Cotching.