Land degradation is among the greatest challenges in Australia. The primary causes of land degradation include water erosion, wind erosion, loss of vegetation, and salinity, and a little more than 50% of the total rural land area requires some form of treatment because of the mentioned problems. Water erosion is mostly widespread in Eastern Australia whereas wind erosion, vegetative degradation, and salinity are the problems of the arid region because of the effects of drought and overgrazing.
Reports state that “globally, around 24% of the world’s agricultural land is considered degraded. In Australia, this figure is estimated to be close to two-thirds (66%)”.
This blog discusses the types and causes of land degradation so that it can be determined how land degradation impacts food production in the country.
What is Land Degradation?
Land degradation is the process in which the environment is impacted by several human-induced processes that act upon the land. It is the disturbance caused to a land that is considered to be undesirable. Since the term ‘land’ includes rocks, soils, minerals, and vegetation and animal habitats, a combination of which forms landscapes.
Types of Land Degradation
- Soil Erosion: Removing vegetation from the surface of the soil makes the land susceptible to erosion by wind or water, and sometimes both these agents combine to remove the soil surface. Soil erosion as we are aware, is a natural phenomenon and has occurred in Australia over the years.
- Water Erosion: Depending on vegetation cover, soil type, structure, and slope, water erosion occurs in different ways. The severity of rainfall is among the major factors in determining the amount of soil that is transported down a slope.
- Sheet Erosion: This type of erosion occurs in certain areas when the energy of raindrops and water flows moves thin, uniform layers of soil particles flow down the slopes depositing them at the base or carrying them to waterways where the sediments are carried to lakes or the sea.
- Wind Erosion: Like sheet erosion, wind erosion is also caused by heavy rain. Uniform particle layers are stripped from the soil surface by wind and transported over long distances. Also, through water erosion, nutrients absorbed by soil particles are transported.
- Salinity: Soil salinity is not a new phenomenon in Australia. Wind, rain, and marine ingressions have deposited salt derived from the ocean over millions of years, which is leached through soils into underground aquifers and ground water until a natural balance has been established. There are two types of salinity-
- Dry Land Salinity: At different locations, geology and hydrology combine to provide a point at which water enters and flows underground. Clearing these areas off vegetation, the balance between evapotranspiration and the quantity of water flowing naturally underground down the slope gets disturbed. The volume of water moving through the soil profile enhances and the water table containing dissolved salts increases. Soil waterlogging leads to soil salinity and dry land salinity occurs in the dryer zones.
- Irrigation-Induced Salinity: This happens when the irrigation water penetrating through the soil exceeds the dispersal capacity of underground qualifiers and drainage systems. Irrigation induced salinity happens primarily in South Australia and the Murray Darling basin.
- Soil Acidification: Acid Soils occur over only a relatively small part of Australia, particularly in the higher rainfall areas of New South Wales, Western Australia, and Victoria. In these areas, soils become more acidic due to the current farming practices. Other causes of acid soils include an increase in organic acids that rises from accumulated organic matter and the removal of plant products that tend to be alkaline, leaving soils acid. Adding lime is the easiest solution to the issue of acid soils.
Causes of Land Degradation
- Deforestation: Forests play an essential role in maintaining soil fertility by shedding leaves, which contain many nutrients. Forests also help in binding soil particles with the help of the roots of vegetation. Hence, cutting forests affect soil adversely.
- Excessive Use of Fertilisers and Pesticides: Fertilisers are crucial in increasing food production but their excessive use has caused a possible environmental threat. Excessive use of fertilisers leads to an imbalance in the number of certain nutrients in the soil, which imbalances the vegetation. Pesticides are chemicals used to control unwanted herbicides, arboncides, insecticides, or any other chemical that has biocidal activity affecting rodents, arachnids, or any other population.
- Overgrazing: Overexploitation of pastures is caused by an increase in livestock population. Grass and other types of vegetation cannot survive and grow in the area, and lack of vegetation cover leads to soil erosion.
- Water-logging: Excessive irrigation and improper drainage facility in the fields lead to a rise in the groundwater level. The ground water mixes with surface water used for irrigation and creates water-logging. Ground water also brings salts of soil in a dissolved state to the surface where they form, a layer or sheet of salt post-evaporation which is known as salinity.
- Desertification: The process of land degradation in arid, semi-arid, and dry sub-humid areas is known as desertification which results from several factors including climatic variations and human activities. Mismanagement of forests, overgrazing, mining, and quarrying are the major causes of desertification. Desertification and land degradation lead to global warming by reducing plant cover and increasing soil exposure, which in turn changes the energy balance of the area. At the same time, climate change also intensifies desertification and land degradation.
Soil degradation affects the growth of crops and yield by decreasing root depth and water availability and nutrient reserves and soil erosion lead to loss of yield by affecting soil organic carbon, nitrogen, phosphorous, potassium contents, and soil pH.
The aforementioned types and causes of land degradation in Australia have significantly affected food production in the country.
To know more about land degradation in Australia and other agribusinesses, browse through the KG2 website, Australia’s largest independent farmer database or get in touch with us.