Dry-summer strategies

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Strategies to get through a dry summer  

 

Despite the uncertain factor of rainfall, technology has facilitated better decision-making with an enhanced understanding of available soil moisture and improved forecasting models.  

 

By Lisa Miller, Research & Extension with Southern Farming Systems, the Victoria Drought Resilience Adoption & Innovation Hub’s South-West Node 

 

Tools such My Farm Dashboard allow farmers to access a number of decision-support tools in one platform. It is easy to sign up, chose your location, draw in your farm boundary or import your existing farm maps, then choose what data information cards you want. This information is tailored to your location. Most of the data cards are free with some requiring third party subscriptions. 

Strategies to get through a dry summer The key data cards required for creating your summer strategies are:  

  • Growing season rainfall – Reported in monthly rainfall and in long-term monthly deciles1 where all the annual rainfall years are divided into 10 equal portions, so that decile 1 shows the lowest 10% of rainfall records and decile 10 shows the top 10% of rainfall year records.    
  • Seasonal forecast rainfall – is reported in terciles2 for 30, 60 or 90-day forecasts for your farm. A tercile distribution is where the predictions are divided into 3 predictions: close to average, wetter than normal, or drier than normal.   
  • Soil moisture – links up to the nearest farm moisture probe, showing the plant-available water and how this compares with last year. These are reasonably good ballpark tools.  
  • Pasture biomass – subscribe to the Australian Feedbase Monitor – Cibolabs – for satellite estimations of feed on offer across the farm at 10-metre resolution assessments, or use MyMLA for a free subscription, but note this will be at the reduced accuracy of one-hectare resolution.  
  • Ag commodity prices – if you’re thinking of selling or purchasing.  

Using Rokewood as an example (see graphic), the season is currently tracking close to a decile 2, or the lowest 20% of rainfall years. In the next 30 days, the models are predicting a 48% chance that it will be drier, with a moderate confidence level. The plant-available moisture was sitting at 70%, down by 28% compared with last year.  

Using the above information with a feed budget which utilises the starting feed on offer, the expected monthly growth (which was thought to be very little given the drier seasonal forecast), estimated amount eaten by grazing stock (approximately 30kgDM/ha/month from a stocking rate of 10 DSE/ha or 1kg DM consumed per DSE) plus 5% monthly loss in pasture decay and wastage from November through to March, allows us to predict that feed on offer will likely drop below 1,000kg DM/ha in January or February. Knowing this allows us to plan to destock pastures to maintain groundcover. Therefore, we will need to either plan to feed stock earlier or longer than normal, reduce stock numbers or put in a fodder crop to fill this feed shortage.  

You can find some excellent decision-support tools here, including:  

  • Frost Economic Scenario Calculator 
  • Lime Assist 
  • Decision Wizard 
  • Pasture Paramedic 
  • Probe Trax 
  • My Farm Dashboard

1 – a decile is each of 10 equal groups into which a population can be divided, according to the values of a particular variable  

2- a tercile is any of the two points dividing a distribution into three parts, where each contains a third of the population 

 

See here for part 2 of our Dry-Summer Strategies series, where we look at preparing now for earlier livestock feeding, with tips to think about in drier times.