Down to Earth with Bob Freebairn: Coping with predicted rainfall and temperature changes

It is an easy to use app - plus it's free - and it projects seasonal rainfall and temperature changes for most agricultural areas of Australia.

Whether one is a climate change believer, or like many farmers just acknowledge the enormous natural climate variability, this app is worth a look and worth an analysis for any given property.

My assessment is that according to their projections for many areas, we will be able to cope with these climate predictions should they be correct.

Their assessment for our farm at Purlewaugh, east of Coonabarabran in Central West NSW, is for similar rainfall distribution throughout the year (autumn, winter, spring, summer segments).

Many other areas have the same prediction.

This supports data from the app CliMate, which for many areas has not detected significant changes in rainfall.

Combined with similar rainfall predictions is the common, but I think yet to be proven, feeling that rain events may be more intense and scattered.

It needs to always be appreciated that Australian climate has always been extremely variable.

My Climate View projects an increase in warming for most districts and for most of the year, on average.

For example, for our area up to 2045, an increase of around 0.7 degrees to the average temperature throughout the year is projected, with slight variation in upwards trend from season to season.

Combined with the higher temperature forecast is fewer frost events - but not necessarily an earlier finish date - at crop flowering but more heat stress events.

Agricultural management to best cope with projected climate change, in many respects, are similar to what is already considered good management.

Plant breeders of all the main crops are also striving to upgrade attributes that coincide with aspects like hotter temperatures and perhaps more erratic rainfall.

For example, crop breeders are striving to improve heat tolerance during the growing season of both winter and summer crops. Genes have been identified, and more are likely to be found, that improve heat as well as drought tolerance in many of these crops.

Crop variety selection may require adjustments to warming temperature.

For example, quick maturing spring types may require a later sowing window.

Spring types with later maturity genes are likely to be more suited to current main sowing windows.

Winter habit varieties may well flower later as it will take longer to fulfil winter habit requirement in warmer times.

A wide range of varieties with various winter habits and spring maturities already exist so it may mainly need a reshuffling of choosing varieties for different sowing windows.

Warmer temperatures will have a positive as well as a negative impact on pastures and crops.

Warmer winters will have the most positive impact for many areas as growth is largely restricted by cold.

Less frosts and warmer winters are likely to result in greater dry matter production per millimetre of stored and rain received water.

Pasture variety choice may also need reassessment should temperatures increase, especially winter species like annual legumes.

Because of normal climate variability, there is already a greater appreciation for earlier maturing annuals to ensure more reliable seed set, even in so called better rainfall environments.

For example, in a dry spring year, such as this one for many areas, early maturing legumes such as sub clover and serradella began flowering in early August and have set reasonable seed.

Longer maturing varieties have commonly failed to seed down this spring.

Efficient soil storage of rainfall during the fallow for cropping and within a pasture becomes even more important if rainfall is likely to be more erratic.

Many found, after the breaking of the drought in 2020, how important stubble was for pasture recovery, erosion prevention and for cropping fallow moisture storage.

Warmer springs, summers and autumns also reinforce the expanding role for tropical pasture species as they have an extended growing period and are efficient in using rainfall over these months.

There is also a good range of long-lasting drought hardy varieties, and they can coexist well with winter species like legumes.

Next week: Tropical grass big help in providing drought feed