By Dominic Naidoo
World Soil Day was commemorated on the 5th of December with the United Nations Food and Agricultural Organisation (FAO) observing the theme of “Soils, where food begins.”
The Earth’s soils have truly taken a battering since man began settling down and cultivating crops and herding animals. With soil quite literally being the foundation of civilization as we know it, we cannot afford to degrade anymore of this precious resource.
Soil degradation threatens nutrition and is recognised as being among the most important issues at a global level for food security and sustainability.
World Soil Day 2022 and its campaign “Soils, where food begins,“ aims to raise awareness of the importance of maintaining healthy ecosystems and human well-being by addressing the growing challenges in soil management, increasing soil awareness and encouraging societies to improve soil health.
Soils possess the extraordinary ability to form, store, transform and recycle nutrients which we need to produce 95% of our food. Thus, healthy soils are the basis for healthy foods.
ISRIC World Soil Information eloquently states that “soils provide anchorage for roots, hold water and nutrients. Soils are home to myriad micro-organisms that fix nitrogen and decompose organic matter, and armies of microscopic animals as well as earthworms and termites. We build on soil as well as with it and in it.”
There are 92 naturally occurring chemical elements on Earth. Of these, 18 are essential for plant growth and of these 18 elements, 15 are supplied by soils.
Macronutrients such as nitrogen, phosphorus, and potassium are needed for plants in large amounts. Boron, copper, iron, manganese and zinc are also essential for plants but are only required in small amounts.
If we hope to survive as a species in the long term, we need to make sure our food production systems are 100% sustainable and for this to happen we need to maintain a balance between nutrient input and output.
The FAO lists nutrient inputs as synthetic and mineral fertilisers, organic residues, biological nitrogen fixation and atmospheric deposition and outputs as crop harvests, soil erosion, loss of organic matter in the soil as well as greenhouse gases emissions.
Soils have the ability to store massive amounts of carbon dioxide sequestered and pushed into the soil by plants and trees.
To take full advantage of soil-based carbon sequestration as a climate solution, we would need farmers to change the way they farm. This is a major social and economic challenge with no easy solutions. As the science of carbon sequestration is in its infancy, monitoring, verifying and quantifying carbon sequestration will be a challenge which must also be overcome.
When soils are nutrient-depleted, they lose their capacity to support crops and go on to produce nutrient-deficient food and when nutrient content is too high, it represents a toxic environment for plants and animals, pollutes the soil, water and the atmosphere and negatively contributes to climate change.
The FAO estimates that around 33% of global soils are already degraded with the trend accelerating.
This is mainly due to unsustainable soil management practices, causing a massive decline in food vitamin and nutrient content. Several factors are responsible for this, including the loss of soil organic carbon and biodiversity, nutrient imbalance, soil erosion, pollution, high salinity and the overuse of fertilisers.
Add the 24 billion tons of fertile topsoil lost to erosion every year, and we will have a global food security crisis on our hands sooner than later.
Losing fertile topsoil leads to low crop yields, crops with low nutritional value and even crop failures. This will in turn lead to hunger, malnutrition and poverty.
Nutrient imbalance has been identified by the FAO as one of the top ten soil threats. Hidden hunger, also known as micronutrient deficiency, is attributed to nutrient-poor diets and is linked to nutrient-depleted soils.
With more than two-thirds of the world's population lacking one or more essential minerals, we cannot afford to not do something about it and one of the biggest things we could do right now to change how we interact with our soils is to stop pumping it with helpful but harmful chemical fertilisers.
When bio-geochemical cycles are not respected, the nutrients removed through harvest need to be replaced by fertiliser. Fertilisers are chemical substances or materials from mineral, synthetic, organic or recycled sources.
The average yield attributable to synthetic and mineral fertiliser inputs is 40 to 60 percent in temperate climates and often much higher in the tropics. Synthetic and mineral fertiliser use has increased by 500% in the last 50 years, and in the case of nitrogen fertilisers, this figure rises to 800%, causing a surplus of reactive nitrogen in the environment that has devastating consequences.
In 2020, 266 million tons of synthetic and mineral fertilisers were used in agriculture globally. In comparison, the estimated quantity of manure used in 2020 is 28 million tons.
Thirty countries use more than 90% of the mineral and synthetic fertilisers in the world, and four countries, China, India, United States of America and Brazil, alone use more than 50% .
Overuse of fertilisers causes soil and water pollution through nutrient leaching, alters biogeochemical cycles, eutrophication of water bodies and greenhouse gas (GHGs) emissions.
In highly fertilised areas, between 50-60% of the nutrient inputs become a major source of pollution to groundwater, freshwater, and coastal waters. In Europe, 45% of Cd contamination of cropland is caused by certain mineral phosphorus fertilisers.
Globally, there is a nitrogen surplus. This basically means that the amount of nitrogen added to the soil is greater than the amount of nitrogen removed by crops. As a result, almost half of the applied nitrogen through fertilisers enters the food chain and the rest is lost into the environment.
38% of agricultural emissions come from the release of this nitrogen, which is a potent GHG with a global warming potential 300 times higher than the one of CO2. On the other hand, nitrogen fertilisers are responsible for feeding 48% of the world’s population.
While there is an overuse of fertilisers in the majority of developed countries, smallholder farmers, particularly from vulnerable countries across Africa, Latin America and Asia, lack access to organic and inorganic fertilisers and are currently facing a 300% increase in fertiliser prices, already impacting food production prospects and farmers livelihoods in many countries.
The answer to the crisis is not simply to facilitate the production of more fertiliser, but to increase fertiliser use efficiency and strengthen and promote alternative sources of fertiliser.
Soils and food security
Soils have a key role in all four dimensions of food security, availability, access, utilisation and stability. The chronic lack of micronutrients from soils and diets causes severe and often invisible health problems.
The average nutritional value of the main crops has declined since 1950, and some vitamins and minerals have decreased by 15 to 40% leaving around two-thirds of the world’s population at risk of deficiency in one or more essential mineral elements.
According to the FAO, global food systems need to increase output by 60% by 2050 with this number rocketing to 100% for developing nations.
Sustainable soil management could produce up to 58 percent more food but even at its most efficient, won’t be able to meet 100% of food needs.
Alternative sources of fertilisers such as manure and bio-fertilizers should be promoted with an ongoing pursuit of new cheaper, cleaner and more efficient agri-technologies.
Other solutions to managing our soils more sustainably include:
The re-carbonisation of soils by increasing organic carbon matter can improve physical, chemical, and biological soil properties, boosting nutrient content and reducing the dependence on synthetic fertilisers.
Nature-based solutions such as using microbes to dissolve and sequester nitrogen, biofertilization, composting, recycling of food waste, crop diversification and soil resting are all excellent ways to rebuild the health of our soils.
The most important stakeholders in the soil cycle are farmers who should be at the centre of plans for the maintenance and enhancement of soil fertility and sustainable nutrient management.
Strengthening of national capacities on sustainable soil nutrient management, technical support, and financial incentives are part of the root solutions to soil fertility loss and nutrient imbalances of the Global Soil Doctors Programme.
Sustainable soil management is still the most cost-effective solution to increase the content of nutrient in soils and improve crop yields for food security and nutrition.
Soil is our life support system. It nourishes our food, blooms our flowers and provides foundations for our very civilisation to build on. We have taken it for granted for too long. It is time we nurture our soils just as much as it nurtures not just us, but all life on Earth.
Dominic Naidoo is an environment activist and writer.
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