JOHN KERIN. Australian soils.

Dec 4, 2018

We live in the driest occupied continent. Most of our soils are old and fragile. Rain is variable in our most arable areas and our precipitation to evaporation ratio is low. Dust storms and soil exposure caused by unprecedented, catastrophic bush fires in Queensland in the last weeks of November remind us of the fragility of our land mass, 60% of which is in the stewardship of our farmers and graziers. To many, but not all, of these landholders it is not a mystery that soil and water, as with the relevant sciences, is the basis to all agriculture. It has been calculated that each of our meals costs 10 kg of soil. Food security is a real debate in a world facing the accelerant of climate change on our resource base; care of our soils becomes critical. 

A large proportion of our soils is derived from the underlying rock base, but soil formation is slow (10-75 mm per thousand years). Australia is so worn down and weathered that much of our land mass is covered by regolith (which also inhibits mineral exploration) and some by Aeolian dust, in land formations such as dunes and swales and e.g. on west-facing slopes. Dust and silt is washed or blown into inland basins. Some parts of our soils are formed by or contain this dust, of less than 20 microns, which can be picked up by heat and wind from these basins in the centre of our continent and blown west to east into the Tasman Sea as far as New Zealand. The source of most of this moving soil (dust) is centralised in the vast overlapping border country of NSW, Queensland, South Australia and the Northern Territory, with another source in western Victoria.

Estimates of our soil loss and land clearing and that of many countries in the world are staggering. While calculations of soil loss, quantitatively and qualitatively, are not exact and vary greatly, the Food and Agricultural Organisation (FAO) and the International Food Research Institute (IFRI) estimate the annual world-wide loss to be 24 to 75 billion tonnes per annum, respectively, i.e. 10 tonnes for every person on the planet. Both organisations can advise on ways to measure and limit soil loss. References to the planet having lost half of its top soil in the last 150 years are common. It is the impact of wind and water erosion which tells us that maintaining soil cover is imperative.

Our latest dust storm was over 500 kilometres in length, eventually blowing over country from Canberra/Sydney into Queensland. It was not as spectacular as the dust storm which hit Melbourne in February 1983. On average we have dust storms every two to three years.

Also the effect is not as spectacular as the more visible fluvial soil erosion, salinity and broad scale land degradation. Much of this is as a result of past practices (over-clearing), ignorance and belief in short-term profit, because there is no obvious immediate reward or market for sound management. This characteristic is also a feature of efforts to improve carbon sequestration in our soils.

What is the extent of land clearing? Again, both quantitative and qualitative measures are inadequate and imprecise. However, we know that 428,000 hectares were cleared in NSW in the early 1970s and 395,000 hectares were cleared in Queensland in 2015 (two-thirds of the annual rate of clearing in the Amazon Basin, if continued). The qualifications to this are that, in cropping land, some of the clearing may have related to single trees per hectare being removed to allow easier use of machinery, and that in some grazing country it is necessary to clear to maintain already cleared land or land that can be safely pushed over as drought feed. Further, country in the semi-arid zone, when over-grazed, gives rise to woody weed invasion.

Conservative governments find it harder to resist farmer pressure to clear land for ‘development’ or, in the case of the Nationals, the ‘right to clear’ as a land right tends to be an imperative to its ‘agricultural fundamentalism’. The anti-science view of the National Party carries over into the denial of climate change, which exacerbates the effects of drought, soil loss and bush fires.

It is not as if we are still not actively researching the challenges we face. Soil Science Australia recently attracted 452 delegates to a conference in Canberra. The funds-starved CSIRO still researches in its area of land expertise. Former Prime Minister Gillard appointed former Governor-General, General Michael Jeffreys, as the National Soil Advocate. He has reported twice to the Commonwealth Government, the latest being to the Prime Minister in 2017 – no response yet.

It is not as if my tale of gloom is all pessimistic. Victoria and South Australia have made great strides in soil retention since ending large scale land-clearing.  The initiation of a National Soil Conservation Programme (Landcare) and the Decade of Landcare by the Hawke Government, the CRC programme, Land and Water Australia (now eliminated), the advent of Whole Farm Planning and availability of verifiable Environmental Management Systems, added to the growing awareness by graduates being involved in corporate farming have, at least, changed the attitudes of many farmers and graziers. The development of many techniques such as minimum till and cell grazing and the possibility of more astute use of our coming digital technologies, all give hope that the challenges can be met. Sound, simple application of concepts of ‘regenerative agriculture’ at broad-scale level (as advocated by Charles Massey), carbon capture and organic farming are catching on. Many landholders are showing how sound, intelligent, profitable practices can be carried out. Why can’t more?

While you would think that sounder management practices, concentrating on resource base issues should be its own reward, more policy work, leadership and co-ordination at national level needs to done. We live in anticipation.

John Kerin was Minister for Primary Industry 1983-91.


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