What is soil degradation?
Soil is usually not given the credit it actually deserves. We often dismiss it as dirt under our feet and forget that it is amongst the most precious resources for human beings.
Soil is an entity that has an inherent structure with certain physical, chemical, and biological properties. It also has many processes that enable it to be a well-run, fully functioning ecosystem. Some of these include soil texture and structure, the water cycle, nutrient cycle, and soil texture.
What functions does soil perform?
For one, soil is the primary source of healthy food production. Having healthy, well-aerated, and nutrient-rich soil provides us with good, fresh food that is an absolute requirement for our survival. Hence good soils are essential for food security.
Soils host a quarter of the world's biodiversity. From bacteria to mammals, soil hosts a myriad of organisms that increase biodiversity and keep the soil ecosystem in check. Soils also store as well as filter groundwater. Think of the soil as a sieve. With the layers present in the soil, they filter out unnecessary particles from the water and make the groundwater as clear as possible.
Did you know that soil also locks carbon from the atmosphere? Soil organic carbon helps to mitigate global warming and climate change. Of the total carbon in terrestrial ecosystems, 80% is found in soil!
What is soil degradation?
When the inherent structure of the soil changes, its productive capacity decreases, and its ability to support plants and animals diminishes. This is known as soil degradation or land degradation. Soil degradation includes soil quality changes, soil erosion, compaction, loss of soil structure, and soil salinity.
When processes like deforestation, overgrazing, and intensive cultivation occur, they expose the lower layers of the soil to wind and water erosion. This damages the fertility of the soil and also disrupts cycles of water, carbon, and nutrients, leading to soil degradation.
Around 10-20% of the world’s drylands and 24% of the world's productive lands are degraded (see more). The end product of soil degradation is a desert. Soil degradation ultimately leads to stripping the soil of all of its natural properties which leads to desertification.
Did you know? It takes about 500 years for an inch of topsoil to form. (Longer in cold and dry climates).
How is soil degradation caused?
The population of the world increasing at an exponential rate is naturally raising the demand for agricultural commodities. This has lead to incentivized and easy conversion of forests and grasslands into farms and pastures. The transition leads to the soil in the area losing its inherent structure and properties beyond its abilities to repair it on its own.
One of the main causes leading to soil degradation is deforestation. When you remove trees from the soil, the roots which held onto the soil particles no longer bind them and the soil is free to move around. In addition, the leaves, twigs, and other parts of the plant that provided organic enrichment to the soil are no longer present which changes the soil structure.
Many crops like soybean, palm oil, and cotton are often grown in deforested land and worsen the natural soil in those areas. When the land loses its fertility, the farm is moved onto the next cleared forest and the cycle repeats.
Overgrazing reduces ground cover, causes soil compaction of the land by wind, rain, and livestock. High rates of erosion and topsoil loss are seen in areas that are overgrazed.
Unsustainable agricultural practices
Although the range of chemicals used on crops like pesticides, insecticides, and weedicides increases crop production in the short run, it often has disastrous impacts on the chemical structure of the soils. They also disrupt the existence of microorganisms in the soil. In the long run, all these lead to infertile soil which is starkly different in structure and function from the original properties.
Apart from these common causes of soil degradation, intensive cultivation, forest fires, and construction work can all also lead to soil degradation.
How is soil degradation going to affect us?
The loss of topsoil and destruction of soil structure means that crops cannot be cultivated for long and leads to loss of arable land. This would lead to a drastic decline in global food production and higher food prices.
The structure of the soil changes so much when it is degraded that it is sometimes not able to hold on to water. Eventually, this lead to desertification which would mean the land is completely barren and damaged beyond repair. Problems like salinization of the soil and soil compaction also increase with degradation.
Besides the direct effects of degradation on the land, it also has negative impacts on the environment. The soil that degrades away causes sedimentation and pollution in nearby water bodies. They clog the waterways in marine and freshwater habitats causing the aquatic life population to decrease.
When land is transformed into a pasture or a crop field, this land often loses much of its water absorption and retention capacity. This leads to most of the water flowing off into nearby water bodies which can increase incidences of flooding.
Another important factor that should be considered in recent times is the removal of the carbon mitigating potential of soil and the associated global warming that will occur due to soil degradation.
Can we combat soil degradation?
The productivity of eroded soils can be remedied using innovative strategies to remedy lost soil structure and functions.
You could promote sustainable land use practices like agroforestry, and permaculture, and crop rotation which would provide crop cover and also improve the water retention capacity of the soils. If you practice farming, you could try to integrate these practices in small ways in your farm. For instance, trying to not leave the land bare by retaining vegetation on the soil.
Most solutions to mitigate the problem of soil degradation require scientific solutions. Organizations like the WWF (World Wildlife Fund) and GEF (Global Environment Facility) actively work to decrease deforestation in areas prone to soil desertification and work on reclaiming degraded lands. Many companies have moved to sustainably farm their products and promote sustainable agricultural procurement.
As an individual, you too could take initiative to help build soil in your local communities. Consider composting. The skills and education to grow your own produce too, may be an alternative to reduce the pressure of intensive agriculture on soil systems.