Generally, conservation farming requires equipment modifications relative to conventional farming techniques, and may require some initial capital investment to replace unsuitable machinery, although conservation tillage may be done using more traditional, manual farming methods. Frequently there are also other demands on residues, which take priority such as fodder, thatching and construction. Although erosion control was cited as the farmers' main reason for not burning crop residues any more, an important pointer to the benefits due to improved soil moisture conditions was evident in This technique is most likely to be successful when associated with precision planting and controlled traffic, in which the passage of all machinery wheels is restricted to permanent tracks. The yields achieved by early adopters on only 4 ha in encouraged others to try, and the method spread rapidly to about 3 ha by and has continued to increase since. On slopes of percent stone lines at 25 m spacing have doubled sorghum yields and reduced runoff by 23 percent Zougmore et al. The precise form and management of contour ridges and tied ridges vary considerably, with the optimum design and management being dependent on the crop, rainfall and soil type.
If the tree canopy is high, accumulated rainwater drops that fall off the leaves may be larger than normal raindrops and can fall with sufficient velocity to cause more damage to the soil than if there were no tree cover. The use of residue covers for conserving soil moisture in the topsoil and increasing yields is particularly important in regions with limited rainfall and high evaporation rates. If they are laid out on the level contour they may have some small additional effect on increasing water in the soil Figure Mulch, cross tied planting ridges and an earth bund as backup provide multiple means of catching rainwater for the benefit of young tea. Representatives of government and private organizations who can contribute to the solution of the problems should also participate. Pineapples and sisal resist the effects of drought due to their thick leaves that slow down water loss by transpiration.
Sourcebook of Alternative Technologies for Freshwater Augumentation in Africa
A cover crop may be sown to serve as a planted fallow. They are recognized as the most cost- and time-efficient technique for rehabilitating very degraded lands in the Sahel, and are an excellent means of establishing tree seedlings so that agroforestry practices can be introduced Ouedraogo and Sawadogo, Early planting at the beginning of the rains has several advantages. Examples of materials that may be used as mulches are grasses and sedges, banana leaves and pseudostems Plate 38 , shrubs such as Lantana and wild sunflower Tithonia , forest litter and tree loppings Plate Where rainfall is erratic the situation is complicated, and becomes more than just a matter of water use efficiency.
The cultivation platform may be continuous along the slope bench terrace, Plate 53 or discontinuous orchard or platform terrace. The efficiency of rainwater use and grain yield were greatly increased by P fertilization on deep soils, but not on shallow soils. In contrast, inflexible long materials, such as woody branches of tall bushes that are not easily flattened by raindrops, will develop a low contact cover and so have less influence on the speed of runoff flow Plate The main disadvantage of applying mulch is the cost or labour of collecting, transporting and applying the mulch. Maize is often planted on the flat, and the ridges constructed at the time of the first weeding about 30 days after planting, which saves labour.