The Link Between Soil Health and Human Health and the Consequences of Soil Degradation in Africa

Categories Nature, Science

Quality food production and food security have several components, including the production of sufficient amounts of food, adequate nutrient content in the food products, and the exclusion of potentially toxic compounds from the food products. The soils in which plants grow play a role in all of these areas, and they also influence human health in more ways than most realize.

One major way that soils influence human health is through their ability to act as natural filters by removing contaminants from water and thus preventing water-borne diseases. The contaminants, including sewage, are removed by soil through physical capture as the water moves through pore spaces, through chemical sorption to solid surfaces, and through bio-degradation carried out by microorganisms living in the soil.

Secondly, approximately 78% of the average per capita calorie consumption worldwide comes from crops grown directly in soil, and another nearly 20% comes from terrestrial food sources that rely indirectly on soil.

The ability to produce nutritious crops in sufficient amounts depends on soil properties and conditions. In particular, soils that have well-developed structure, sufficient organic matter, and other physical and chemical properties conducive to promoting crop growth lead to strong yields and are thus important for food security.

Soils are a major source of nutrients: Out of the approximately 29 elements considered essential for human life, 11 elements are typically divided into four major elements (H, O, C, and N), which constitute approximately 99% of the human body; and seven minor elements (Na, K, Ca, Mg, P, S, and CL), which make up another approximately 1% of the body. Another 18 additional elements, called trace elements, are considered essential in small amounts to maintain human life.

These elements are also either essential or beneficial to plants, which take them up from rocks or from the soils derived from them. Therefore, soils that provide a healthy, nutrient-rich growth medium for plants will result in plant tissues that contain most of the elements required for human life when the plants are consumed.

In nature, soil microbes and fungi work with plants to dissolve the minerals and make them available to sustain plant growth. These microbes selectively take up and concentrate the correct amounts and ratios of mineral nutrients that plants, animals and humans need. They also selectively exclude and prevent the uptake of toxic elements from the inert, often toxic, soil environment.

In summary, soil erosion; continuous cultivation of farmlands without replenishment of soil fertility; reduced vegetation cover; inadequate soil and water loss control measures; increasing soil acidity and toxicity; and, loss of soil structure and nutrient content, among others have disrupted microbial uptake processes leading to inherently poor and unproductive soils with low organic matter and hence threatening not only crop production, but also livestock, fish and human health too.

Soil microbes and fungi that previously sustained the natural solubilization, uptake and cycling of essential nutrients, have been destroyed due to increased use of inputs of chemical fertilizers and bio-cides (pesticides, fungicides, herbicides) to enhance yields and profits from industrial crops.

Heavy cultivation and resultant topsoil loss through wind and water erosion has also disturbed these important microbial communities.

Consequently, most plants grown today are totally dependent on fertilizer inputs and now take up their nutrients in whatever concentrations and ratios are present in the soil-water solution, without the benefit of nutrients being filtered by soil micro-organisms.

As a result, plants contain very high levels of the nutrients added as fertilizer (usually nitrogen, phosphorus and potassium), but little or none of the other 26 essential and trace elements that are not soluble and were previously made available by the microbial community.

Accordingly, humans in return lack these nutrients and trace elements. Selenium, for example, is an essential nutrient – required in minute amounts – for the enzymes that kill cancer cells. Yet today’s food does not contain such nutrients.

Thirdly, soils that contain substances which may be toxic to humans, can pass those substances on to humans through crop uptake. Such toxic substances include heavy metals, the ones of greatest concern for human health being Arsenic, Lead, Cadmium, Chromium, Copper, Mercury, Nickel, and Zinc.

The toxic substances also include organic chemicals that have been deposited into the soil both naturally and through human activity. A large amount of these organic chemicals come from the agricultural application of herbicides, insecticides, and nematicides. Soil pollution with organic chemicals is not limited to farming areas. Soils in urban areas are also polluted with organic chemicals as a result of industrial activities, coal burning, motor vehicle emissions, waste incineration, and sewage and solid waste dumping. Many of the organic chemicals deposited into the air and water also end up in the soil eventually.

Toxicity to humans can also come from soil pathogens because even though most organisms found in soil are not harmful to humans, soil does serve as a home for many pathogenic organisms including some bacteria, fungi, protozoa, helminths and viruses. Pathogenic viruses are usually introduced into soil through human septic or sewage waste.

Arising from the above, and in parallel with our adoption of today’s foods and diets, there have been marked increases in a number of diseases. There is evidence of a direct link between diet and many of these conditions, including cancer, diabetes, heart disease, chronic fatigue, and auto-immune and mental illnesses.

In conclusion, population growth, industrialization and climate change threaten soil health, and therefore human health, but the degradation can be rolled back.

This trend can be reversed by recognizing that healthy people need healthy food from healthy soils. Healthy soils grow food with the aid of the natural microbial processes that ensure correct uptake of nutrients and exclusion of toxins.

Solutions that will enhance production of healthily functioning plants include reintroducing composting of food and organic waste; using nature-based solutions and regenerative agricultural practices which return nutrients to the soil, build soil (and microbial) health and grow plants with the nutrient content to meet our body’s needs.

Additional solutions include adopting regenerative landscape management practices which support soil and water protection, rehabilitation and conservation; watershed management; soil testing, composting and manuring; agro-forestry; good agricultural practices; integrated pest management; ecosystem-based adaptation; and, conservation agriculture which advocates for minimum soil disturbance, permanent soil cover and crop diversity.

I am an epic introvert, who quickly becomes an open book when I pen what’s in my significantly fertile mind; fertile as a result of bombardment by realities that are continuously captured by my inquisitive eyes, ears which are constantly rubbing the ground, through constant reading, and through dreaming too.

Writing provides an opportunity to ‘say’ what my unapologetic quiet mouth will not say; which not only soothes me, but also bequeaths to me a relief, a release, and a hope that the written words will change the world, even if only one person at a time.

And so should you seek, that’s where to find me; deeply tucked inside the blankets of reading, seeing, listening, dreaming, and then writing.

3 thoughts on “The Link Between Soil Health and Human Health and the Consequences of Soil Degradation in Africa

    1. Thanks Francesca for the compliments. I am consultant in matters agriculture in general. i will get in touch with you. Thanks again.

    2. Thanks Francescah Munyi for your comment. My work mostly involves guiding policy makers to take action based on science. Regarding soils, the development of a “National Soil Management Policy” is at an advanced stage. My number is 0738430191.

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