By restoring the structural, mineral and biological health of our soils we can rebuild the resilience of our landscape and better mitigate the landscape degradation and global challenges currently being faced. For effective regenerative landscape management, our soils must be managed in an integrated way with our water and vegetation resources and our biodiversity.
Healthy soils are essential for healthy plant growth, human nutrition, drinking water filtration and a landscape that is more resilient to the impacts of drought or flood. Healthy soil helps to regulate the Earth’s climate and stores more carbon than all of the world’s forests combined. Maintaining soil health is critical for biodiversity - a handful of fertile soil contains more microorganisms than human beings that have ever lived. Two-thirds of Earth’s species live beneath its surface.
Soil organisms contribute a wide range of essential services to the sustainable function of all ecosystems. They act as the primary driving agents of nutrient cycling, regulating the dynamics of soil organic matter, soil carbon sequestration and greenhouse gas emission, modifying soil physical structure and water regimes, enhancing the amount and efficiency of nutrient acquisition by the vegetation and enhancing plant health. These services are not only essential to the functioning of natural ecosystems but constitute an important resource for the sustainable management of agricultural systems .
The carbon content of soil is one of the key indicators of its health and is a master variable that controls many of these processes. It is the carbon content of soils that largely governs their capacity to absorb, retain and supply moisture within the soil and to sustain active plant growth. Every gram of carbon in the soil can retain up to eight grams of water.
Mycorrhizal fungi thrives in healthy soils,
enhancing the ability of plant roots
to access soil moisture and nutrients.
Soil carbon helps support a healthy balance of nutrients, minerals and soil microbial and fungal ecologies, improving soil fertility. It promotes the sustained production of essential food and fibre as well as the capacity of plants and animals to resist disease, insect infestation and climate stresses. Increased soil carbon levels therefore also have the means to reduce our reliance on costly fossil fuels and other farming inputs.
However, current rates of soil erosion by wind and water across much of Australia now exceed soil formation. Research from the CSIRO released in July 2013 indicates that Australian soils are losing about 1.6 million tonnes of carbon per year from wind erosion and dust storms alone (read more here). Across Australia’s dryland cropping and grazing sector it would be unusual to find actively farmed soils with a carbon content of greater than 1.5%. Ideally, soil organic carbon levels for quality agriculture should be around 5%.
Currently on both the 1.5 billion hectares farmed globally and the 40 million hectares farmed in Australia, we are:
- losing 1-20 tonnes of topsoil for every tonne of food produced
- losing 5-10 tonnes of carbon per hectare per annum through current farming practices