Soil Insights

Host: | Date: 03 Oct 2018

  • GRDC Podcast
    Podcast

    GRDC Podcast: Soil Insights

    Mike says while we have a wealth of knowledge in Australia about above-ground plant components, we don’t understand enough about roots – how variable they are between species and how they respond to different soil conditions.

    Date: 03 Oct 2018

    Listen on Soundcloud Listen on Apple podcasts

When Mike Bell was a humble soil science undergraduate his lecturer forecast that he would spend his career looking below the ground, and 30 years later, Mike has to admit he was right.

The University of Queensland professor has spent a lifetime researching plant root behaviour and development and was rewarded for his efforts when he won the 2017 GRDC Recognising and Rewarding Excellence award.

The prize was a six-week study tour of Germany, Switzerland, France and the UK to investigate what European scientists were learning about how roots respond to soil conditions, nutrient distribution and fertiliser application.

Mike found that the Europeans are doing tremendous work on discovery science around root function and how roots work, how they sense gravity and how they convey that sense of gravity into roots growing down, not up.

They have developed scanning equipment based on medical technologies such as X-ray, CT scanners and MRIs designed to assess roots, rather than taking the traditional approach of digging up plants to measure them.

Mike says while we have a wealth of knowledge in Australia about above-ground plant components, we don’t understand enough about roots – how variable they are between species and how they respond to different soil conditions.

Australian soil nutrients are increasingly being found in patches, he says, not distributed across the soil profile, and how roots respond to these nutrient patches determines how a crop performs.

As native fertility erodes we also resort to fertilisers, but there are a limited number of places where we can put the fertiliser in the soil profile and we must ensure the roots can access it.

In Europe, Mike found they have the opposite problem. Their soils are highly fertile but there are caps on fertiliser use, so they regulate inputs of animal manures from their intensive animal industries.

Another research focus we have in common is how roots can access water in different parts of the profile at different times of the growing season.

Quite often Australia’s topsoils are dry, so if we have nutrients in topsoil layers and water in subsoil layers, how does a plant allocate resources to growing roots – where does it put its focus?

The European work is focused heavily on selecting crop varieties for deep rooting characteristics, to find water deep in the profile late in the season to get them through to harvest.

The big unknown for both European and Australian researchers is what happens if you fertilise a field and all your phosphorus is in the top 10cm or in a fertiliser band at 15cm. Do we still see deep root development?

Also of interest was work in Nottingham, UK on how roots responded to an air gap in the soil. Mike says the plants changed their morphology, stopped putting out branches, and changed their anatomical structure as they grew through the gap.

This has particular relevance to Australia where producers are deep placing fertiliser, which disturbs the soil and leaves air gaps behind that they rely on rain and time to gradually settle back down. If a bad job has been done on fertiliser placement and most of it is sitting in an air gap, the crop will suffer.

Mike has welcomed recent GRDC funding for a post doctoral fellow to work on the interface between sorghum and winter cereal breeding programs, assessing how genotypes with certain root characteristics are altered by different nutrient distributions.

He plans to catch up with his new UK and German research colleagues at the International Root Research Symposium in Israel later this year and says he hopes to see the development of an exchange program for Australian graduate students and research fellows with the UK or Germany.

Further information

Professor Mike Bell
University of Queensland

GRDC Project code: HYS00002