The demands animal agriculture makes on our environment

Balwyn meeting April 2015 report. Guest speaker: Oliver Hornung

I have worked in agricultural research or over 40 years, in the United Kingdom and in Australia, but found Oliver’s talk both interesting and informative, but also rather disturbing. My work had always been in a rather specialised topic of plant pathology, and I was quite unaware, not so much of the impact of agriculture as of the impact of animal agriculture. In those early days one of the major research projects in the UK was the direct production of protein from crop plants. It was well recognised even then that the production of protein through livestock was an inefficient process. Oliver’s well researched and referenced talk showed me, just how inefficient that process was.

Although he first showed that world agriculture used 37% of our land area, equivalent to that of Asia – that did not surprise me. Oliver then showed that 22% of the land was forest, 9% was grassland, 22% was barren and two or three% was urban. But he also showed that the large majority (70%) of agricultural land use was for animal agriculture, and that did surprise me. When the land used for the production of stockfeed (about 10%) was also taken into account, the land left for other crop plants was surprisingly much less than I had expected.

Most animal production relies heavily upon grain, fed in some kind of feedlot, but in addition, over 25% of fish production is actually used in animal production. Ninety percent of cattle, 98 % of poultry and 70% of sheep are grain fed. Oliver went on to show how much grain was used to produce one kg of the meat of different kinds of animals. For example, he showed that two kg of grain was required to produce one kg of chicken meat, four kg of grain to produce one kg of pork and 7-14 kg grain to produce one kg of beef.

Water is, of course, widely used in agriculture. Of the world’s water production, 70% is used in agriculture, 10% is used by households and the remaining 20% is used by industry. In his succeeding graphics, Oliver used a bath tub to symbolise 140 litres of water. To produce one kg of grain, approximately 3,221 litres of water is required. However, 4,300 litres was required to produce one kg of chicken, more than 10 times that is required to produce a kilogram of pork and the production of 1kg beef required 110 bath tubs or 15,000 litres of water. The production of a single Burger requires 2500 litres of water.

Waste production in animal agriculture is a major problem, especially in relation to water quality because it enters the environment in an untreated form. For example, 5,000 pigs produced the waste equivalent of 20,000 people and 5,000 steers produced nearly the waste equivalent of a million people. In the United States alone, 40% of the land area, and 56% of the water is used for animal agriculture. Animal agriculture produces 130 times the waste of the entire population.

Land is also a major resource in agriculture. A meal based upon pork requires the use of 3.12m square of land, a single hamburger requires 3.61m square and a chicken curry requires 1.36m square. In contrast, only 0.19m square is required to produce a plant-based diet. Overall, a vegetarian diet results in 50% less carbon dioxide than a diet based on meat, produces one third the waste, uses less than 10% the water and 1/18th the land.

People in developed countries consume 20 times the meat and dairy products above the world average, and that proportion is expected to increase. Although population growth has been steadily decreasing over recent years, the human population is still increasing, and there is no sign of that changing. Agricultural industry ranks second in its contribution to climate change. A major factor is that the production of methane is more serious than the production of carbon dioxide. Although it has been estimated that by improving agricultural techniques it would be possible to obtain net zero emissions of glasshouse gases by the industry. However, inevitable population growth will continue to make more demands on land and other resources used in agriculture.

Habitat loss is the most important single factor reducing biodiversity. It is responsible for 85% of threatened species, both plant and animal, and although attempts are made to mitigate the problem by replanting forest and bushland this only results in one tree planted for every 100 cleared. Queensland has the largest amount of forest remaining in Australia, but it also has the highest current rate of forest removable, and 92% of the cleared land is for animal agriculture. Nearly 80% of that land clearing on the east coast of Queensland results in increased run-off to the Great Barrier Reef and consequential loss of coral.

With regard to loss of biodiversity, high grazing regimes result in low diversity although numbers of some common species increase. These include Noisy Miner, Masked Lapwing, Crested Pigeon and Australian Wood Duck. On the other hand, light grazing retains more habitat diversity and so retains more bird and animal diversity. Under such regimes birds such as Brown Thornbill, various fairy wrens, White-browed Scrubwren and honeyeaters can survive. However, with the loss of any particular habitat, particular species must necessarily also be lost. It was suggested that most birds susceptible to habitat loss through grazing have already been lost. Personally I doubt that. Although habitat loss has been occurring for over 300 years, the majority of that would have been in the last 150 years or so, and it does seem to be a never-ending process. So many species seem to have small, localised habitats and have nowhere to go if those habitats are lost. That seems a bleak future for biodiversity.

But Oliver did not talk about human population growth. Man’s future on earth may be even more bleak. I personally suspect that, if we double our population over the next 60 to 100 years, as seems likely, we would need to double our agricultural production. Unless we greatly improve our agricultural practices, or reduce our demands on land, we will have no more new land to use thereafter. With our current population at about s billion, our maximum sustainable population could perhaps be as little as 50 billion. And we could be in sight of that figure within 100 to 200 years.

We must surely start to do something about that now.

Contributor: Ron Garrett

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