Periods of extended dry weather, more commonly referred to as droughts, impact availability of resources such as water and feed for livestock, limit growing season rainfall and deplete soil moisture. Growing seasons can be significantly reduced or absent altogether during periods of drought.
Historical records can help to form a picture of the likely annual and growing season rainfall for a district. Utilise this knowledge to make strategic decisions about the types of enterprises to run or decisions about investing in major infrastructure, (e.g. water storage, irrigation equipment, silos or barns). Considerations such as the frequency with which droughts have occurred in the past, and their duration, can aid strategic decision making and ensure the business’ continued viability.
Albeit at different scale, less-frequent or shorter dry spells or droughts can still cause considerable challenges to a business. For example, the lack of an autumn break (an opening rain sufficient to establish crops or a winter feed wedge for livestock) can mean that despite adequate subsoil moisture crops can fail to establish or may not be sown at all if the break does not come. Actions such as maintaining stubble cover, changing fertiliser strategies and placement or supplementary feeding, can all help to make the most of a moderate break when (and if) it occurs. Droughts can cause crop failure or quality issues and may require tactical responses such as cutting for fodder or grazing crops rather than harvesting. Drought can also mean increased prices for feedstock and bedding materials in piggeries.
Disruption to water supplies and reduced likelihood of rain is likely to require tactical responses to manage limited water supply. Actions such as finding alternative water sources and managing existing water sources will lessen the risk of fully depleting water supplies, and optimises catchment capacity to make the most of water in the event of rain. Prioritising the use of irrigation water on crops may also become necessary, for example avoiding extended the frequency between irrigations during flowering of cotton. In a water scarce year where growing rice may result in reduced returns, a tactical decision could be to participate in the water trading market, or planting an alternative crop, instead of growing rice. Ensuring irrigation systems are operating at optimum efficiency should be conducted regularly to ensure water is always being used efficiently.
An unusually dry period has varying impacts depending on the previous seasonal conditions and time of year, therefore risk mitigation responses need to vary accordingly. The Chances of extremes – unusually dry tool indicates the chance of rainfall being in the lowest 20% of the historical range for a specified time (ranging from a week to three months). A dry outlook for spring might prompt a livestock business to secure supplementary feed early, in anticipation of increased demand during summer. A dry outlook during winter could trigger reassessment of the planned inputs for a grain crop. An example of such a dry outlook for late autumn is shown in Figure 2.
Figure 2. Example of the decile bar chart tool, showing the probability of an extreme dry (decile 1 & 2) event for a location between May and July. Reproduced from www.bom.gov.au
There are a range of potential challenges regarding the impact of drought, which may differ for different enterprises, summarised in Table 1, with suggestions for tactical responses listed. Some responses might be targeted at a specific issue, but in turn provide a solution for multiple challenges.