Compiled by Isabel Carter
Photo: ICRAF ©
Alley cropping is a technique that is very useful for improving poor soils, providing fodder for livestock and protecting the soil from heavy rainfall.
Alley cropping is a simple way of combining tree-growing with crops. Rows of suitable trees are planted about 5 metres apart, usually by direct seeding into the soil at the beginning of the rainy season. In between the rows of trees, crops or vegetables are grown as usual. On sloping ground, the rows must be planted along the contour – across the slope. Alley cropping may also give some protection during irregular rainfall as the rows of trees help to trap rainfall in the soil.
The tree seeds are planted close together in the rows so the young trees form a hedge. If possible, try to mix several different species to form a hedge. Once the trees reach shoulder height (1–2 metres high) they are cut right back to just 20–30 cm in height. The leaves can be left on the ground as a mulch to rot down and add nutrients to the soil. Alternatively, they can be collected and used to provide animal fodder. The remaining stumps quickly grow back and the cutting can be repeated for many years.
Alley cropping adds plant nutrients and improves soil structure. It protects soil from heavy rains. It is low-cost and easy to do, although it does require a lot of labour to cut back trees. Without regular cutting, they will grow tall, develop thick trunks and compete with the crops.
Alley cropping should not be used in very dry areas. The trees will be more difficult to establish. Once established, the rows of trees will use what little water is available in the soil and make it more difficult for crops to grow.
Alley cropping requires a good supply of seed from the right kind of trees. It is important that only legume trees are planted, as their roots add plant nutrients to the soil. In many areas legume trees are already growing and they often produce plentiful supplies of seed. Legume trees produce seeds in pods and usually have small, divided leaves. They also tend to have deep roots that do not compete much with crops for water. If possible, get local advice on the best species to plant.