Reflecting on almost 40 years as a cereal agronomist, Dr John Angus of CSIRO Plant Industry, Canberra, suggests that the ability of farmers to innovate for themselves will help ensure a positive and sustainable future for southern Australian broadacre farms.
Traditionally, there had been up to a 30 year delay between research and on-farm adoption.
The next big challenge, or opportunity, broadacre farmers face will be re-integrating livestock and grazing with cropping.
“Opportunities are there to introduce perennial pastures, grazing of crops and using failed crops as a feed source,” Dr Angus told a packed audience at The University of Western Australia, while delivering the 2011 Hector and Andrew Stewart Memorial Lecture, titled ‘The remarkable improvements in Australian mixed farming’ and hosted by The UWA Institute of Agriculture.
Increased farm sizes, more cropping, a greater proportion of broadleaf crops and improved wheat quality and yield marked fundamental changes to the mixed crop-livestock farms of southern Australia during the period from 1980 to 2000.
Dr Angus proposed that the major contributors to improved wheat productivity had been breeding, including resistance to disease and stresses, crop management, including planting times, nutrition, stubble management and crop sequences and, lastly, but most importantly, adoption and innovation by farmers.
He quantified wheat yield improvements as being about 65 per cent due to crop management and singled out Western Australian grain growers for their commendable innovations in the stubble management and no tillage space.
“An important, but previously underestimated management change, has been the break-crop benefit of broadleaf crops which control cereal diseases,” Dr Angus said.
“Healthier cereals following break crops respond better to nitrogen fertiliser, which can be confidently and strategically top dressed in favourable seasons.
“Greater spreading of lime, which is needed to grow canola on acid soils, which are especially prevalent in WA, improves the yield of subsequent crops, enabling the return of lucerne and barley to previously acidified regions.
“More water being used by higher yielding crops and by lucerne-based pastures is also reducing the risk of salinity and water logging.”
While crop yields fell in the past decade, this was mostly due to the effect of droughts and because break crop benefits and supplementary nitrogen were not expressed in dry conditions.
Dr Angus believed break crops could improve the yields of subsequent wheat crops, suggesting lifts of 0.8 tonnes/ha after canola, 0.5 t/ha after oats and a staggering 1.82 t/ha after lupins.
“It’s obviously a real shame, therefore, that the lupin area has declined in recent years,” he said.
Legumes such as lupin, chickpea, field pea and faba bean also offered the benefit of hydrogen fertilisation, which stimulated growth by up to 10 per cent due to increased hydrogen in the soil.
“Partly offsetting lower returns from crops, however, was increased lamb production, based on more perennial pasture, grazed crops and fodder conserved from droughted crops,” he said.