Climate challenge
Pastoral farming can contribute much to reduce emissions of carbon dioxide, writes Murray Crombie.
Pastoral farming, the term for rearing livestock rather than growing crops, has been blamed as a major contributor to greenhouse gases. But pastoral farming can contribute much to reduce emissions of carbon dioxide, CO2, which is one of the main contributors to global warming.
Biological activity in soils and ocean sediments captures and stores this gas. Global soils hold about three times more carbon than occurs in the atmosphere and 240 times the amount emitted by fossil fuels annually, while the oceans store some 93 per cent of the earth’s CO2.
The notion that world human populations should convert to veganism, and thereby remove greenhouse gas-producing mammals and other herbivores, is a nonsense. The world human population is growing, clamouring for greater food supply.
Refusing animal proteins produced anywhere, even on untillable, hilly and forested lands, is a denial of that demand. Going vegan is a personal choice, but know this: plant production monocultures have downsides. They command use of the best soils and continuous cultivation degrades those soils, releasing carbon back into the atmosphere. Such farming also requires huge investment of time, machinery, fuels, fertilisers, and pesticides and still produces greenhouse gases.
Soil carbon sequestration – that is, the storage of greenhouse gases in the soil – occurs naturally in the symbiotic interaction of soil, fungi, plants and plant roots. In grasslands, it’s augmented substantially by grazing animals which promote vigorous plant regrowth. Plants are cropped, digested and wastes moved to the soil surface to be consumed and converted by worms, macro-fauna and multitudes of microbes, bacteria, and fungal organisms, which are fed and stimulated by faeces and urine nutrients.
The products of the life and death of these soil organisms creates underground a store of humus, a complex organic matter derived from decomposed plant and animal tissue. Humus is fundamentally important for abundant plant growth, improving soil water holding capacity and providing a reservoir of growth nutrients.
This soil carbon sequestration occurs in every continent of the world. In savannahs, veldts, prairies, pampas, and steppes, all places where grasslands and herbivores exist together, and has done so for millions of years.
In America, since tillage, the preparation of land for growing crops, began, most agricultural soils have lost 30 to 75 per cent of their organic carbon, and scientists speculate that increasing the amount of carbon stored in global agricultural soils by just four per cent would stop the increase of CO2 into the atmosphere.
Pastoral farmers throughout New Zealand are already adopting regenerative agriculture methods to do just this, treating the soil/humus layer as a highly important medium for storing nutrients and the matrix of beneficial living organisms which survive there.
New Zealand pastoral farming methods, supported by scientific study, include maintaining living plant cover and feeding livestock in sustainable numbers out on the land 365 days a year; keeping soil cover and reducing damage to resprouting plant pastures grazed or harvested for supplement, and preferring mixed species such as grasses, legumes and herbs, which support a wider range of soil, plant and animal life, more effectively capturing and converting nutrients.
In addition, pastoral farmers practise rotational grazing, allowing root systems to recover. Rotationally grazed pastures have greater soil carbon storage rates. Complete soil cultivation is avoided when forage cropping or renewing pastures, in favour of no-till methods, and fertilisers are carefully applied to supply just those minerals that are needed.
So what now for NZ pastoral farming? The answer lies with farmers prepared to believe that better farming methods are needed and working together to tackle climate change.
It also needs a government that is co-operative and directs science and research to find, fund and communicate best farming practice. Soil carbon sequestration could be brought into the Zero Carbon Policy (currently it’s not) and used to offset farmers’ accomplishments against emissions.
The answer also lies in an informed public. It’s our right to judge the quality of practices which impact on the environment and speak any dissatisfaction. But, it’s also OK to express our confidence and support of the valued things farmers do. It’s our duty also to reduce our own carbon footprint.
Going vegan is a personal choice, but know this: plant production monocultures have downsides.