Natural Sequence Farming Could Affect Global Climate Change

Natural Sequence Farming is a descriptor used when sustainable agriculture mimics the once highly efficient functions of the Australian landscape. NSF pioneer Peter Andrews of Denman in New South Wales and coordinator of the NSF movement, Duane Norris of Hardy's Bay, New South Wales explain how NSF techniques could re-couple environmental carbon and water cycles not only to improve farming yields but to avoid soil erosion and reduce carbon dioxide emissions.

Agricultural practices such as clearing, burning, plowing, draining, and irrigation, have become commonplace across the Australian continent, as they have elsewhere. Their effect on the organic carbon content of soil has led to a decline in soil quality across farmland on the continent with levels currently a tenth of what they were 200 years ago prior to the major European settling of Australia.

Andrews and Norris point out that this has had implications for atmospheric carbon dioxide levels and will continue to impact on global warming if farming practices are not modified. "Soils hold twice as much carbon as the atmosphere, and three times as much as vegetation," the team explains, "But carbon in soil exposed by common agricultural practices leads to the oxidation of the carbon and the release of carbon dioxide into the atmosphere." Estimates suggest that soils that once contained carbon matter 4,000 to 10,000 years old, are now holding carbon that is a mere two years old because poor management of livestock grazing leaves soil de-vegetated and in an oxidizing state.

Plants extract carbon from carbon dioxide in the air by photosynthesis, the team says. This carbon is critical to soil health and plant fertility, but it is lost when a ploughed paddock is left bare with no plant cover. More carbon is released when grassland and trees are cleared. However, when vegetation is allowed to break down, even if it is weedy cover, the carbon content of the soil is raised and growing conditions improve.
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