Soil holds a significant number of nutrients that plants use for healthy growth. Good quality soil of the right porosity, strength and stability is important if farmers are going to get good, healthy and nutrient-rich crops. The structure must be stable in order to get the correct balance of air and water, as well as the right combination of aggregates to hold it together.
However, during flooding, severe wind or under poor farming practices, soil is eroded to the extent that it's no longer the nutrient-rich substance needed by plants. Soil erosion doesn't just impact food production either. It can destroy habitats and biodiversity on land and in water. The movement of soil can also disturb matters off-farm, causing road damage, disrupting utility supplies and causing human health concerns with poor, dusty air quality.
While soil erosion has improved significantly across the country, South Australia still considers it the highest priority threat to agricultural lands.
Causes of soil erosion
Soil erosion is a natural process, but a combination of weather conditions and farming practices increases the rate at which it occurs, making it a serious concern. Weather like rain, flooding, drought and wind naturally cause soil to move over time. However changing land management techniques have disrupted natural levels of soil movement and heightened erosion.
Plants of all sizes play a key role in holding soil together, maintaining its structure and physical condition. As humans remove these plants and expose the ground beneath, the risk of weather conditions directly affecting soil placement increases. Over-grazing animals on a land parcel can also contribute, as they wear away the soil and eat the plants responsible for holding it together.
Dramatic climate events, while beyond the control of human beings, are capable of affecting soil erosion. Serious drought conditions, as have been reported over recent years in areas of Australia, leaves land dry and dusty – and more easily moved by wind or water. Moreover, these sorts of conditions predominantly affect the top layer of soil, which is considered the most fertile section.
Preventing soil erosion
Soil takes thousands of years to build up, but is wiped away very quickly without proper protection. In one experiment cited by the Australian Government, a farm without adequate protection lost 22 tonnes of soil per hectare, whereas neighbouring farms with better prevention schemes lost much less and maintained better nutrient levels.
Preventative measures in themselves are nothing new, with some programmes having begun as early as the 1950s. However, it's important that brokers understand how farmers can protect their investment today, alongside the right insurance policy.
Protecting land from soil erosion involves considering how the land is used, if it can be better protected from the elements and controlling soil movement before it becomes an issue.
1) Protective surface cover
The risk of erosion is significantly reduced with as little as 30 per cent ground cover, according to the Queensland Government. Plants provide a crucial source of cover by placing a protective layer of leaves and foliage between the elements and the soil. They also maintain soil structure with their root systems, and help to slow the speed with which water runs off the land.
During harvest season, farmers can protect their soil with very little effort by leaving the stalks, leaves and other parts of the crop that fall to the ground. Together, these excess plant parts provide surface cover which adds a significant layer of protection to the top soil.
2) Less disruptive tillage practices
The process of preparing land for planting is known as tillage. Traditionally the practice involves turning over the soil so it's ready for new seeds. New practices, such as sowing seeds in narrow slots, reduce soil disturbance and leaves more residue on the surface to protect against weather conditions.
At the other end of the season, farmers can practice 'stubble retention', which involves increasing the height at which crops are cut, to offer more protection to soil after harvesting.
3) Redirecting rain water
Planning irrigation so that water and soil is kept within a paddock can help to reduce soil loss by around 80 per cent, according to the same Queensland Government advice. By channeling runoff around the farm with contour banks and filter strips, you slow down the speed of flow as well as how much soil is depleted or deposited elsewhere. It's not just farmland that's protected by good irrigation practices, as it also prevents excess runoff spilling into rivers and waterways or onto roads.
4) Land management
Changing grazing practices, such as moving animals between paddocks regularly, gives land a chance to recover and limits the impact animals have on soil erosion. Some farmers undertake clay spreading to strengthen soil and make it more difficult to erode. Meanwhile, they might also use trees as windbreaks in heavily affected areas.
Developments in technology now enable farmers to improve soil management by monitoring conditions and land practices to provide long-term recommendations.
As an insurance broker, having this knowledge is invaluable. Understanding the challenges your farmers face allows you to think laterally about how you can help them manage their risks and protect their business. Take a look at our brokers page for further information about what Primacy Underwriting offer.