Increasing agricultural production is widely acknowledged as a priority area for Africa, and essential in addressing food security problems, human vulnerability to environmental change, and achieving Millennium Development Goal (MDG) 1 to eradicate extreme poverty and hunger (NEPAD 2002, UN Millennium Project 2005c). One key challenge, as discussed in Chapter 3: Land and Chapter 9: Genetically Modified Crops, is the problem of land productivity and related low crop yields. In Africa, low productivity is a factor of the ecological reality and low investment in agriculture. Productivity is further threatened by human-induced changes and natural processes; key among these are climate change and variability, and invasive alien species.

Synergistic growth in the chemicals industry could have positive spin-offs for the development of agriculture (UN Millennium Project 2005c). The use of agricultural chemicals, including fertilizers, herbicides, fungicides and insecticides can help improve yields, for example. Chemicals may also be beneficially used in livestock production as vaccines and in animal feed.

Figure 6: Global fertilizer consumption 2001 Chemical use in the African agricultural sector is likely to increase as a result of the growing commercialization as well as the growing focus of development agencies on improving yields of small farmers. In Africa the per capita use of fertilizers is relatively low, as shown in Figure 6. The UN Millennium Project notes the need for small farmers to be supplied with soil nutrients and other related technologies (UN Millennium Project 2005c), while at the same time recognizing that there must be increased use of sustainable agricultural practices if natural assets are to be preserved (UN Millennium Project 2005a). Environmentally-friendly options may include the use of nitrogen-fixing plants and agroforestry, as well as the application of bio-fertilizers, such as animal waste and plant mulch.

Agricultural extension and aggressive corporate marketing have contributed to increased use of agricultural chemicals. In many places, small farmers under pressure to engage in the market, produce improved crops and increase yields have abandoned traditional, more environment-friendly, practices. This may have a range of negative environmental impacts including on soil and water quality. In Africa, despite the poor levels of comparable data over the last five decades, trends indicate an increase in the concentration of nitrates and phosphates at river mouths, this mirrors the trends in developing economies elsewhere including in Southeast Asia (UNEP 2002). Inappropriate fertilization and irrigation practices can result in salinization and acidification of soil, and in Africa, chemical-related soil degradation affects 51 million ha of land, with about 40 million of these being nutrient-deficient and salinity affecting about 6 million ha (ECA 2001).

Food security and pest management

Box 1: What are POPs and PCBs?

Persistent Organic Pollutants (POPs) are chemicals that:

  • Are extremely stable and persist in the environment;
  • Bio-accumulate in organisms and food chains;
  • Are toxic to humans and animals and have chronic effects such as the disruption of reproductive, immune and endocrine systems, as well as being carcinogenic; and
  • Are transported in the environment over long distances to places far from the points of release.

Poly-Chlorinated Biphenyls (PCBs):

  • Are persistent organochlorines;
  • Permeate the air, water, and soil;
  • Are toxic to humans;
  • Bio-accumulate in organisms and food chains; and
  • Settle into fats and oil, so fatty fish and marine mammals can provide rich sources of these pollutants. Cows grazing on contaminated grasslands or eating tainted fodder can transfer PCBs into the fat in their meat and milk. In fact, most foods can carry tiny traces of these toxic chemicals.

Source: Mörner and others 2002

As discussed elsewhere in this report (Chapter 3: Land and Chapter 9: Genetically Modified Crops) the challenges of achieving food security are complex and require a multidimensional approach. In many parts of Africa, pests pose a significant threat with locust invasions, for example, repeatedly threatening food security especially in Western Africa (See Chapter 3: Land).

Chemicals are an essential aspect of pest management and Africa has relied extensively on the use of POPs (Box 1). However, it is important for Africa to begin to look for alternatives to many of the highly toxic chemicals it uses in pest control. Chemical use is a costly option. The highly toxic chemicals used to deal with locust plagues, for example, not only affect locusts, but also humans, animals, including livestock, and the environment. Apart from these dangers, spraying also requires huge logistical resources, which many of the poor countries most affected by locusts cannot afford (IRIN 2004). Additionally, storage of chemicals and the re-use of chemical containers also threaten human health.