Promoting Food Security in Tropical Africa: An Understanding of the Soil Health of the Region

The majority of the 800 million people that inhabit sub-Saharan Africa (SSA) live in rural areas and depend on agriculture for employment and livelihood. But the past three decades have witnessed a stagnant or declining growth in agriculture. Thus, as at 2009, the Food and Agriculture Organization of the United Nations (FAO) recorded that more than 265 million people in sub-Saharan Africa were hungry and malnourished and the region remains the only part of the world where the absolute number of the poor and people facing hunger and malnutrition is increasing. To begin to understand why the agriculture sector has underperformed, it is vital to understand the nature of the soil health of Tropical Africa.

Most of the soils of tropical Africa were formed from rocks of Pre-Cambrian origin. These rocks are made up of granites, quartz and quartzite-like materials. Soils formed from these materials are typically sandy. They are dominated by low activity clays that have very limited capacity to hold on to the exchangeable bases such as Calcium and Magnesium that are required as food by plants. We can therefore say that these soils have inherent low fertility. This situation has not been helped by the high temperatures and heavy rainfalls that are characteristic of the region. The high temperatures and heavy rainfall promote excessive weathering of the rocks and the leaching of the nutrients released during the weathering process to zones where they cannot be utilized by growing plants. Although the high temperatures and heavy rainfalls encourage the growth of vegetation, these same forces promote the rapid decay of dead organic materials. The result is that the soils have very low amounts of organic matter. Soil organic matter is crucial as it is the main source of nitrogen, a key nutrient for plants. Soil organic matter is also important for maintaining the buffering capacity of the soil. A soil with high buffering capacity reacts more slowly to changes brought about by management practices such as the addition of inorganic fertilizers.

Having been dealt a difficult hand by Mother Nature how was the tropical African farmer able to grow food for the family? The farmer was keenly aware of the fragile nature of the soils that she/he worked and adopted a system described as “shifting cultivation” for the management. This practice enabled the farmer to cultivate a piece of land for one or two years. The piece of land was then left to fallow for upwards of fifteen to twenty years to regenerate its fertility. This practice worked as long as the population was small. With increased and increasing population, farmers have been forced to stay on the same piece of land. This intensive cultivation has resulted in massive losses of plant nutrients, a process now described as “nutrient mining”.

It has been determined that by 2002, 132 million tons of nitrogen, 15 million tons of phosphorus and 90 million tons of potassium had been lost from 37 tropical African soils in 30 years.

The most efficient way to improve the soil fertility is through the use of fertilizers, primarily inorganic fertilizers. However, data from the International Fertilizer Industry Association (IFA) shows that tropical Africa is not a significant producer of inorganic fertilizers. Therefore, if agricultural production must be boosted through the use of inorganic fertilizers, such products must be imported. However, because many countries in tropical Africa have no access to ports and because of poor transportation infrastructure, fertilizer prices are very high. For example, 1 metric tonne of urea costing USD 90 in Europe would cost USD 400 in Mombasa or Beira on the East African coast, USD 500 in Western Kenya and USD 700 in Lilongwe (Malawi). At these prices, most smallholder farmers cannot afford to buy the fertilizers needed to improve the fertility of the soils.

At the beginning of the new Century, African Heads of States and Governments adopted the Comprehensive Africa Agricultural Development Programme (CADDP) as the framework for the development of the overall economy of Africa. The African leaders committed themselves to allocate a minimum of 10% of national budget to development in four priority areas known as Pillars. Pillar 2 expressly addressees the improvement of rural infrastructure and trade-related capacities for access to markets.

 

In 2006, the Heads of State and Governments met at Abuja at the Africa Fertilizer Summit and declared fertilizer as a “strategic commodity without borders”. Africa’s political leadership is thus well aware of the importance of providing adequate support to agriculture. Africa’s friends and development partners must hasten to the aid of the governments as they struggle to implement CAADP.