occur in the planting pit. Zaï are well combined with stone contour bunds. These reduce the speed of runoff and allow even more retention of water and soil.
Stone contour bunds Stone contour bunds had also been in use in Burkina Faso traditionally, but the challenge was always to follow the contour lines, especially where the landscape is flat. Following the introduction of a low-cost water spirit for measuring land levels it became much easier to determine the correct alignment of stone bunds. Mastering the skill of using the level did not take more than two days. The better aligned stone bunds allowed runoff to spread effectively and evenly through the field and trickle through the small opening between the stones. The practice improved soil condition by trapping sediments and organic matter within the plots thus preventing it from washing away with the rain.
Modified traditional agroforestry At the same time in Niger farmers developed innovative ways of regenerating and multiplying valuable trees whose roots have been lying dormant underneath their land. Based on their experience in managing local woodlands, farmers starting experimenting with a process which became known as Farmer Managed Natural Regeneration (FMNR). Among the mature root systems in the field farmers would choose tree stumps based on the usefulness of the species. The tallest and straightest stems would then be selected, nurtured and protected. At the same time other
stems would be removed. To further promote their growth and production the selected stems would be pruned whilst continuously other stems would be removed. The removal of stems enabled the growth of other crops between and around trees creating an ingeniously modified agroforestry system. The trees generated a number of important benefits: (a) they improved the local micro-climate by reducing wind speeds and evaporation – thus reducing the impact of drought and heat; (b) they provided fodder for livestock (enough for half of the year); and (c) they provided fruits, firewood and medicinal products. Some species also added nitrogen to the soil.
Costs and benefits The benefits in terms of food security and farm productivity have been substantial. They explain the speed with which innovations have spread from farmer to farmer. Most of the improvements are done by farm labour in the off-season. Though these labour inputs are substantial, there are no opportunity cost for them. This was in itself an innovation – as traditionally work on zais was unheard off in the dry season.
Zaï and contour bunds Establishing zaï structures at the beginning of the dry season consists of two main activities, namely digging the pits and covering the bottom of each pit with a 3 cm clay layer. Zaï pits or (planting pits1) come in different sizes and densities (pits / ha), and therefore the amount of labour and costs also vary. Where zaï is combined with stone contour bunds, the bunds also need to be constructed. Below are typical ranges of costs for the establishment and maintenance – including the replenishment of manure – of the pits and bunds. Without these measures productivity is extremely low: 80 kg of sorghum/ha. Zaï and stone bunds can raise yields to 300 to 400 kg/ha in a year of low rainfall to up to 1500 kg/ha in a good year. Experiments show that it is particularly the concentration of nutrients that makes the difference. Further spin-offs of the new zaï systems include the development of market for manure. Herders have started to systematically collect the manure after harvesting for sale since an increase in demand has led to a doubling of the price.
Figure 2: Stone bunds with Sorghum, Burkina Faso
1 Known as tassa in Niger
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