The Problem Today
Currently, 40% of soil in Africa is degraded. Degraded soil diminishes food production and leads to soil erosion, which in turn contributes to desertification. This is particularly worrisome since, according to the UN’s Food and Agriculture Organization, some 83% of sub-Saharan African people depend on the land for their livelihood, and food production in Africa will have to increase almost 100% by 2050 to keep up with population demands. All of this makes soil erosion a pressing social, economic, and environmental issue for many African countries.
Reality on Ground.
Katsina State Government has spent over N6 billion in three years on erosion and flood control across the state, the Commissioner for Environment, Hamza Suleiman, has said.
Suleiman made the disclosure at the opening of a workshop for some participants of Nigeria Erosion and Watershed Management Project (NEWMAP) in Katsina.
“The state government had implemented various projects on gully restoration, storm water, erosion control and flood project before the coming of NEWMAP in the state.
According to him, over N2.8 billion was spent by the government between 2015 and 2017 to tackle some of the 3000 complaints it received from communities affected by various ecological challenges.
“The state government also expended another N3.2 billion in third and fourth quarters of 2017 to 2018 to control erosion in 49 communities.
Can Law Review be the Solution?
“The state House of Assembly will assist in reviewing the existing laws on erosion with the aim of making erosion control a success in the state,”
What is land degradation?
Land degradation is caused by multiple forces, including extreme weather conditions particularly drought, and human activities that pollute or degrade the quality of soils and land utility negatively affecting food production, livelihoods, and the production and provision of other ecosystem goods and services.
Threats to land integrity
Land degradation has accelerated during the 20th century due to increasing and combined pressures of agricultural and livestock production (over-cultivation, overgrazing, forest conversion), urbanization, deforestation, and extreme weather events such as droughts and coastal surges which salinate land.
What does land degradation mean for health?
These social and environmental processes are stressing the world’s arable lands and pastures essential for the provision of food and water and quality air. Land degradation and desertification can affect human health through complex pathways. As land is degraded and in some places deserts expand, food production is reduced, water sources dry up and populations are pressured to move to more hospitable areas. The potential impacts of desertification on health include:
- Higher threats of malnutrition from reduced food and water supplies;
- More water- and food-borne diseases that result from poor hygiene and a lack of clean water;
- Respiratory diseases caused by atmospheric dust from wind erosion and other air pollutants;
- The spread of infectious diseases as populations migrate.
How do we reduce soil degradation?
Use of organic farming techniques: Organic farming involves the application of natural means in farming, to reduce harm to the environment. Some organic farming techniques that help restore the soil include use of green manure (uprooted or sown crop parts incorporated or left on topsoil), cover crops, crop rotation and organic compost.
- Green manure and cover crops: Green manures and cover crops serve as mulch to the soil preventing the soil from wind/water erosion and moisture loss. They also increase the soil organic matter content as they decompose in the soil. Green manure and cover crops that are legumes (plants which produce seeds in pods) have nitrogen fixing ability. The nitrogen fixing bacteria in their root nodules help capture nitrogen from the atmosphere. Green manure and cover crops suppress weed growth. It is a cheap and natural (no herbicide use) method of controlling weeds.
- Organic compost: Organic compost is a generally cheaper method of fertilizing the soils compared to inorganic fertilizers. Compost is a mixture of decomposed plant parts and animal waste. The key benefit of composting is that it increases soil organic matter content. Organic matter improves the soil fertility, the soil structure and its water holding capacity. It also sequesters carbon in the soil. The use of compost reduces use of chemical fertilizers which if applied inappropriately can contaminate neighbouring streams or ground water.
- Crop rotation: This is a farming practice which involves growing different types of crops in one location sequentially. This practice reduces soil erosion, increases the soil fertility and subsequently crop yield.
Soil remediation: Soil remediation involves the removal of harmful contaminants such as, heavy metals, sewage sludge, coal tar, carcinogenic hydrocarbons, liquors and petroleum from soils. Soil remediation can be achieved using biological techniques. This method is called bioremediation. Some examples of bioremediation techniques include:
- Phytoremediation: The use of plants to remove contaminants from soils or to degrade contaminants to a lesser toxic form. Some plants have the ability to extract contaminants from soils. This process is called phytoextraction. The willow (Salix viminalis) is a shrub credited for its ability to extract cadmium from soils. Phytoextraction is one technique in phytoremediation. Some other techniques are phytostabilization, phytotransformation and phytostimulation.
- Bioaugmentation: This is the introduction of genetically modified micro organisms into contaminated soils with the aim of degrading contaminants. The efficiency of this technique depends on a number of factors, some of which are the physico-chemical properties of the soil and the ability of the introduced micro organisms to compete successfully with the indigenous soil microflora.
- Land-based treatments: This includes techniques like land farming and composting. In land farming, contaminated soils are taken to land farming sites and continuously overturned and tilled to allow aeration. In composting, micro organisms present in organic material are used to biodegrade soil contaminants.
When soils are contaminated they constitute an environmental hazard. Soil remediation is always an expensive large scale project; requiring funding or approval by the government or local authority involved.
A good example of a soil remediation project was the restoration of soils contaminated with stockpiles of obsolete pesticides in two African countries (Mali and Mauritania). These soils were restored using composting and land-farming. This project was run by collaboration between the FAO* Pesticide Management Programme, the Wageningen University and Research Centre and the National Institutions of the countries involved.
Desalinization: Soil salinization occurs when high levels of soluble salts accumulate in the root zone. Saline soils frustrate crop growth and reduce crop yield. Soil salinization is encouraged by:
- Formation from parent materials with high salt content
- Low rainfall in arid regions where there is insufficient water to leach salts
- Poor soil drainage system
- Excessive exposure of soil to salty irrigation water or chemicals
Some methods used to restore saline soils are:
- Installing drainage systems to wash salts down the soil profile (this method is expensive and complicated).
- Leaching out saline soils by applying water to contaminated soils to wash salts beyond the root zone.
- Use of salt tolerant plants (halophytes) as bioremediants. Halophytes accumulate salts in their shoots and other aerial plant parts. Examples include Allenrolfea occidentalis (iodine bush), Salicornia bigelovii (dwarf saltwort), Panicum virgatum (switch grass), Sesuvium portulacastrum (sea purslane).
- Application of gypsum (calcium sulphate dehydrate) to sodic soils. Sodic soils have high content of sodium chloride. Gypsum mixed into the layers of sodic soils replaces sodium with calcium, reducing the sodium level.