There are a number of soil management issues that you need to be aware of on your property. These include soil erosion, excessive nutrients, poor soil health, salinity and acid sulfate soils.
Human land use and management practices can increase the natural processes of soil erosion. Vegetation cover protects soil from erosion caused by wind and water, and also reduces mass movement (land slides or land slips). The removal of vegetation by clearing, overgrazing, fire or other activities can cause erosion of fertile topsoil and a loss of productivity. Eroded topsoil will often accumulate in wetlands, streams and dams smothering habitat and reducing water quality, while soil erosion can also degrade or damage property infrastructure, such as fences and roads.
Soil erosion can be a gradual process that is often hard to detect from day to day or it may occur quite suddenly (eg during intense rains or floods). Indicators of erosion include; bare soil, exposed tree roots, muddy water runoff, silted dams and waterways, soil buildup along fences, or the creation of gullies or rills.
Soil Health and Nutrients
Soil nutrients, particularly phosphorus and nitrogen, occur in relatively low concentrations in the Australian landscape. The overuse of fertilisers will lead to excessive soil nutrient build up that will promote weed growth, reduce the health and growth rate of native plant species, and contribute to the development of blue-green algal blooms in waterways and dams.
Soil health on your property can be improved by adding organic matter, such as mulch or composted material, or earthworms and their castings. The addition of organic matter to soil will improve microbial activity, nutrient holding capacity, and reduce compaction of the soil by increasing its structural stability as well as water infiltration and water-holding capacity.
Salt occurs naturally in the Australian landscape. A combination of ancient marine sedimentary rocks, wind blown salt and a comparatively low rainfall have allowed salt to remain in soil and groundwater. Salinity is an issue that occurs across Australia in many forms - dryland, irrigation, urban, industrial and river salinity. Land management practices can cause salinity by raising the water table (eg by irrigation, or by clearing of native vegetation). Care should also be taken when selecting detergents and cleaning products if greywater is to be recycled on your property as many of these products contain salt.
Salinity affects plant growth and water quality, and in a rural environment, can reduce crop yields and production. Salinity also causes damage to houses, buildings and infrastructure. In the natural environment, salinity reduces the health of rivers, streams, and wetlands and vegetation can become unhealthy and die.
Indicators of salinity include dieback of vegetation, patches of earth becoming bare and ‘scalded’, white salt crust on brickwork or the soil surface when dry, corrosion of water, gas and sewerage pipes, unhealthy grasses and shrubs, and development of patches of salt-tolerant plants. Contact the NSW Office of Environment and Heritage to check if your property is located in an area where salinity has been identified.
Acid Sulfate Soils
Acid sulfate soils (ASS) are those soils containing iron sulfide. They are located in low-lying coastal areas - less than five metres above sea level. ASS are known as either potential acid sulfate soils (that is; when iron sulfides are contained in a layer of waterlogged soil), or as actual acid sulfate soils (that is; when they are exposed to air and the iron sulfides react with oxygen to form sulfuric acid).
Sulfuric acid produced from acid sulfate soils has significant impacts on aquatic life, property health, and plants and animals. These include decreasing soil pH (soil acidification), reducing soil nutrient availability, releasing metals such as aluminium, magnesium, and cadmium in levels toxic to plants and animals, corroding concrete, iron, steel and other metal alloys, and damaging buildings, fences and property structures.
Indicators of potential and actual ASS include; cloudy green-blue water, excessively clear water, iron (brown) stained water, poor pasture, scalded soil, and soils which are either dark grey and wet in appearance, or yellow and mottled. Contact NSW Office of Environment and Heritage to check if your property is located in an area where potential or actual acid sulfate soils have been identified before undertaking any activities that may disturb them.