Healthy soil is a prerequisite to achieving sustainable food security. Not just that, but healthy soil creates the foundation of healthy food, which contributes to the local and global food security chain. But in Mzansi, we are losing more and more of that good soil due to soil erosion.
If the chain is disrupted because of soil erosion, understanding the causes and the effects as well as finding ways to mitigate soil erosion is important as a way forward. Agronomist Kagiso Murwa shares her expertise on soil erosion in Mzansi.
To understand soil erosion, it is important to understand what healthy soil is. Healthy soil is a maintained soil with a diverse community of soil organisms that helps to control plant diseases, insects and pests, but it is all under threat because of winds, heavy rains, even running water, and of course, other natural forces that play a role.
What causes soil erosion?
“There are several causes for soil erosion, it is mostly wind and rainfall that is water-related, especially when it is flooding, so these are the main causes of soil erosion,” says Murwa.
According to Jay le Roux, lecturer: department of geography, University of the Free State and Hendrik Smith, conservation agriculture facilitator, Grain SA soil erosion is a natural process, but “it is often accelerated by human activities, for example by the clearing of vegetation, soil tillage or overgrazing. Poor farming practices as well as the trend toward agricultural intensification have been considered to be major causes of erosion.”
Murwa explains that the top soil is the most important because it carries all the nutrients for crops and livestock to be able to survive and grow. If this soil is destroyed due to erosion, it results in an imbalance of the vegetative cover.
“For the erosion, when it comes to wind and rainfall, it erodes your top soils which are quite important for your crops because the most fertile layer of the soil is the topsoil. And it also causes water pollution among others, because whenever the soil is eroded to the place where the soil comes from might have been fertilised and all of those chemicals will land up in your water system,” says Murwa.
Impact on crop and livestock production
Soil erosion can have devastating effects on agricultural lands and farmers in both crop and livestock production can be severely impacted by soil erosion. It can be to a point where the soil is futile, leaving farmers no other option but to “abandon” the demarcated area that was meant for farming, Murwa explains.
“The problem can become very severe, that even the land cannot be cultivated anymore. If their erosion is quite bad, the impact the soil erosion can have on water quality becomes quite significant that some of the chemicals that are applied on the land will end up going into your water streams, which will affect the quality of the water that you would use for livestock as a drinking water. It becomes undrinkable.”
How can farmers regenerate soil or prevent soil erosion?
Farmers regenerate or prevent soil erosion through cover cropping and rotational cropping, to keep the soil full of nutrients that are needed to provide the soil with the best possible vegetative cover.
“The most common way to prevent soil erosion is by covering crops that can be tilted in the soil, especially when it comes time for planting because once the plants start breaking down, they provide nutrients for the agricultural process called rotational cropping,” says Murwa.
Murwa makes an example of rotating legumes and cereals, as well as rotating maize with soya. The following crop will benefit from the nutrients in the soil, which also helps to break the pest cycle on the land.
Effects of climate change on soil
Murwa explains that it is difficult to say exactly how far the soil has degraded in Mzansi, but it’s important to include climate change in the conversation.
“We have seen erratic rainfall patterns, which then results in flooding and these rainfalls erode our soils,” says Murwa.
She emphasises that food security is at stake, therefore finding ways for farmers to adapt is important.
“We need to adopt different methods of farming to try and increase productivity because open lands are not going to be quite easy to work with. Land degradation is a global problem that affects biodiversity and livelihoods with a profound effect on resource-based livelihoods.
“We need to progress to sustainable development goals and overcoming climate related poverty now becomes significant where nearly 60% of land is degraded and this is according to the United Nations Environmental Programme,” says Murwa.
Tips for better land management practices
Mitigating soil erosion is “not a cheap exercise”, Murwas says, so adopting regenerative agricultural practices is important for better land management practices. As well as using irrigation and precision agriculture methods that are discouraging soil erosion.
“Map your land and see how much you need for irrigation and fertiliser, instead of using the blanket approach. So adoption of new technology as far as your irrigation and chemical application [is concerned], is important. To better land management practice, have crop rotation systems and conservation practices in place,” says Murwa.
She emphasises that this is long-term advice, it won’t happen instantly but consistency is key to maintaining healthy soil and avoiding soil erosion.
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