Introduction

An important characteristic of beans, like other legumes too, is their ability to transform atmospheric nitrogen into nitrogen that can be taken up by plants. They do this with the help of Rhizobium bacteria that live in their roots. This property makes beans (and other legumes) an important element in crop rotations. They provide nitrogen not only for themselves, but also for the crops that follow.

The reasons to grow beans on small and medium sized farms are manifold:

• Beans, like other legumes, are a rich source of protein, carbohydrates, minerals and vitamins. Protein content in beans can reach up to 40 %, whereas the protein content of meat is approximately 20 % only.
• Beans are an important staple food in rural Africa and grown widely, only second to maize.
• Beans are relatively easy to grow on small pieces of land.
• Beans fit in very well into crop rotations and provide nitrogen to the crop that follows.
• Beans can be successfully intercropped with crops like maize or cassava.
• Dry beans can be stored and consumed or sold on the market according to need.
• Beans have big demand in both domestic and regional markets within Africa.

Despite all of the above mentioned benefits, bean production still faces a number of challenges in Africa:

• Poor selection of bean seeds - Although many farmers face difficulties in finding good yielding varieties suitable to local conditions, the handling of varieties is also very poor. Normally farmers mix up improved and local varieties in the same gardens, making it difficult to achieve full potential from improved varieties. The harvested beans are further mixed up after shelling and during further planting. As a result of cross pollination, the characteristics of improved varieties are gradually lost.
• Poor quality of seeds - Since virus infection of bean crops is widespread, the bean seeds farmers use for growing the next crop are often virus infested.
• Soil degradation - Bean production in Africa is severely constrained by low soil fertility. In Central and Eastern Africa, the major soil fertility related problems include low available Nitrogen (N) and Phosphorus (P) and soil acidity. Many areas have acid soils poor in nutrients while others are too arid for bean production. Soil erosion is another problem, especially in highland areas.
• Poor husbandry practices - Difficulties in finding suitable material for making a trellis for climbing beans limits the full productive potential of these beans.
• Postharvest losses - Especially during drying and storage, a significant amount of beans is lost through mould. This is a result of insufficient drying and the exposure of the dried beans to water or humidity during storage. Poor sorting of beans is another quality problem. Different varieties, sizes, stones and other waste from threshing are always found mixed with the beans presented to the market for sale.

The aim of this chapter is to introduce organic approaches that can be adopted according to the local conditions, in order to support a more sustainable and profitable production of beans.