Introduction
An example of improved soil and water management on vertisols in the Ethiopian highlands
Water conservation using animal power
Conclusions
Bibliography
A. Astatke and M.A. Mohamed Saleem
The authors can be contacted at the International Livestock Research Institute
(ILRI), PO Box 5689, Addis Ababa, Ethiopia.
Animal traction has been an integral part of most agricultural systems in Ethiopia for thousands of years. There is evidence that cattle were first used for ploughing in the latter part of the third millennium BC (Goe and Astatke, 1989). Today, the traditional cattle economy is directed mainly towards supplying draught oxen.
Ethiopia has a cattle population of 31 million head (FAO, 1994), the largest in Africa, of which 9 to 10 million are used for draught purposes. Zebu oxen are the main work animals and, in pairs, they are primarily used for seed-bed preparation and threshing. Where oxen are in short supply, horses, mules and donkeys are paired with the same species or with others to plough the land (Figure 1). All three equine species are used for transport in most parts of the country. In the lower highlands (below 1 500 masl) and drier regions, camels are used exclusively as pack and transport animals. Where crops and livestock are integrated, crop residues provide the major share of livestock feed. The main livestock outputs are milk, meat, hides, manure and draught power. Livestock are also an economic asset, providing financial security to smallholder farmers.
The human population of Ethiopia is 57 million and is growing at the rate of 3.4 percent annually (World Bank, 1993). During the last two decades, the country was hit by two famines. The first, in 1973/74, claimed the lives of 100 000 people, and the second, from 1983 to 1985, was even more devastating, leaving close to 1 million people dead. Also, a considerable number of people were displaced. Although prolonged and consecutive drought years contributed to these famines, the traditional land use systems cannot support the present population even in normal rainfall years. More food is required if famine is to be avoided in the future.
In this paper a sample of alternative uses of animal traction as possible means of intensifying crop production in some farming areas and the obstacles encountered in the transfer of traction technologies are discussed.
The production environment
The highland ecozone is extremely diverse in its geology and soil formation. It is fragmented by valleys and rivers and into many land forms, consisting of plateaus and flatlands surrounded by escarpments. The main soils are alfisols, vertisols and inceptisols. Stony mountain slopes and seasonally flooded flatlands are marginal for cropping and, therefore, are used mainly for grazing. The major soil-related problems are slope erosion, poor drainage of flatlands and plant nutrient deficiencies.
The rainfall is bimodal, with main rainfalls occurring from June through September and the short rainfalls from February to May. In some highland areas, the short rains are not sufficient to grow crops, and farmers generally prepare their land for planting during this period. The mean annual rainfall in the highlands varies from 500 to 1500 mm depending on the altitude and orientation. In spite of 2 000 mm of rainfall per year, water storage is a common problem in many parts of the highlands.
Mixed smallholder rain-fed agriculture in the Ethiopian highlands is dominated by teff, wheat, barley, sorghum, maize, horsebeans, peas, lentils and a local type of hops. Annual crop yields average from 400 to 1 000 kg per hectare (Gryseels and Anderson, 1983). A widely practiced crop rotation is two consecutive years of cereal crops followed by a pulse crop. Although in some highland areas the fallow period extends Up to five years, because of the growing population and land fragmentation, the majority of farmers are compelled to cultivate the land continuously. continuously Soil fertility is declining in the highlands and the use of chemical fertilizers to replenish soil nutrients is not yet widely used. Less than l 0 percent of the farmers use small quantities of chemical fertilizers or improved seed. Manure is normally dried and used as fuel.
Most farmers own two oxen, a cow, a few sheep, a donkey and some chickens (Gryseels and Anderson, 1983) Sheep and goats require minimum inputs and provide investment and security in times of need Donkeys are used extensively to transport agricultural inputs and farm produce. Ethiopia has an estimated 5.2 million donkeys, 2.7 million horses and 630 000 mules (FAO, 1994).
Livestock productivity is low for all species. The seasonal shortage of livestock feed is acute in the highlands. Grazing on communal lands and fallow plots constitutes the main source of feed, and this is supplemented with straw, crop residues and stubble grazing. As grazing lands are encroached upon for crop production, feed shortages are further aggravated. Preferential supplementation of work oxen and cows in milk with straw or hay is therefore a common practice during the dry season.
Oxen holdings and cropping patterns
Except for some small and very difficult areas of the highlands where hoe cultivation is still practiced, all cultivation is carried out by oxen pulling the traditional plough, the maresha (Figure 2). Farmers in the Ethiopian highlands maintain cows to produce replacement oxen. Cattle reach physical maturity at four to five years of age, averaging around 210 kg for cows and 280 kg for oxen (Mukassa-Mugerwa, 1986). The males are castrated when they reach maturity.
Surveys carried out by the International Livestock Centre for Africa (ILCA)-now the International Livestock Research Institute (ILRI) have shown that the number of oxen owned by a farmer strongly influences both the area cultivated and the cropping patterns employed (Table 1) (Gryseels et al., 1984). To ensure timely cultivation, farmers with less draught power cultivate smaller areas and sow early. The choice of crops is also influenced by the availability of draught power. Land preparation for cereal crops is more labour-intensive than preparation for pulses, for example, and therefore requires more draught power Cereals fetch higher prices than pulses, however, which explains why farmers with less draught power have lower incomes.
The traditional tillage implement
It is not certain when animal-drawn tillage implements began to be used for agriculture. It has been conjectured that the Ethiopians inhabiting the highland areas of the country were introduced to the ard by Semitic-speaking invaders from South Arabia between 1000 and 400 BC (Goe, 1987). Recent archaeological evidence, however, suggests that it may have been used even before the Semitic invasion by Cushitic-speaking peoples from an ancient Nubian region in northeastern Sudan (Goe, 1987). Regardless of who introduced it, the ard (maresha) has remained the traditional animal-traction implement in Ethiopia and has contributed to crop-livestock integration in the country.
The maresha consists of a metal point or tine fastened to a long pole, at the opposite end of which is fastened a wooden neck yoke. At each side of the metal point are two wooden wings that push the soil aside. The traditional implement, together with the yoke, weighs between 17 and 26 kg (Goe, 1987), and is therefore light enough to be transported easily by one person to and from the fields and over difficult terrain. With the exception of the metal tine, which the farmer buys from the blacksmith, the maresha is home-made. It is a versatile implement and can be used on all soil types. Depending on the crop and soil types, two to five cultivations using the maresha are necessary before a field is ready for planting. It is also used to cover crop seeds with soil, except for Eragrostis tef.
1. Impact of ox ownership on area cultivated and cropping pattern at Debre Zeit, Ethiopia, 1980 - Incidence de la disponibilité de bœufs sur la superficie cultivée et la répartition des cultures à Debre Zeit (Ethiopie), 1980 - Efectos de la propiedad de bueyes en zonas cultivadas y modalidades de cultivo en Debre Zeit. Etiopía, 1980
|
Number of oxen owned by farmers |
Average area cropped per farm (ha) |
Area planted with cereal (%) |
Area planted with pulses (%) |
|
None |
12 |
54 |
46 |
|
One |
1.9 |
44 |
56 |
|
Two |
2.7 |
67 |
33 |
|
Three or more |
3.6 |
92 |
8 |
Source: Gryseels et al., 1984.
Each pass with the maresha is made perpendicular to the one before so as to ensure the loosening of all the soil. The depth of the first ploughing ranges from 5 to 8 cm, while the last pass may be up to 20 cm deep. The time required to prepare the land also varies from 100 hours per hectare to 150 hours per hectare for light soils and deep vertisols, respectively (Astatke and Matthews, 1982). The maresha has the advantage of being pulled by a pair of indigenous oxen, each weighing not more than 300 kg. The local zebu oxen can develop a traction power of 0.50 to 0.90 kW (Astatke and Matthews, 1982), depending on the type, moisture content and compactness of the soil, the depth of ploughing and the traction power of the animals.
A serious disadvantage of the maresha is that it is a cultivating implement and therefore of little use for turning the stubble and weeds into the soil. Hand-weeding is the main activity in the agricultural calendar and is one of the most serious constraints in agricultural production. Covering seeds uniformly is another problem when using the maresha, which explains why farmers use double or triple the quantities recommended by research institutes.
Animal-powered surface drainage implement
Research by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) showed that preparing broadbeds and furrows (BB Fs), which are raised beds with shallow ditches in between them on vertisols, increased the grain and straw yields of traditional crops dramatically and also allowed high-yielding crops to be grown (Ryan and von Oppen, 1983). ICRISAT used a wheeled tool-bar drawn by a pair of oxen to construct the BBFs. The tool-bar costs more than US$500, however, and therefore is hardly relevant to smallholder subsistence farmers. In 1986, ILCA, in collaboration with other national institutions, started work on developing low-cost land-shaping implements using local materials. From the beginning of the implement-development programme, farmers involved in on-farm verification were invited to test the implement and their suggestions were incorporated in the design-refinement undertaking.
Several designs and testings led to the broadbed maker (BBM), which is still in use today (Figure 3). It is made of two mareshas connected in a triangular structure. The top ends of the beams are tied together and connected to the yoke as in the traditional method. To maintain the 1.2 m between the maresha tips, a crossbeam is tied between the two poles at about 1 m from the lower tips of the poles. The steel wing of the mould-board is then attached to each of the inner flat wings of the maresha to push towards the inside and form the BBFs (Figure 4). A chain attached to the edge of the metal wings not only shapes the beds evenly but also covers the seeds uniformly. The power requirement of this BBM (0.62 kW) is lower than that of previous designs. This can be attributed to the metal wings, which have lower frictional force through the soil than those made of wood (Astatke and Kelemu, 1993). The area transformed into BBFs in six working hours using a BBM pulled by a pair of oxen ranges from 0.4 to 1.2 ha. This large variation depends on the filth state of the top soil and the condition of the animals. The combined cost of the wings and the chain is estimated at US$30.
Impacts of surface drainage created by animal power on crop yields and labour use
A series of on-farm tests verified that the effect of the drainage achieved by the BBF on crop growth was substantial. There was a consistent increase in crop and straw yields, although the increase over traditionally planted crops did vary between locations and years (Asamenew et al., 1993).
In the baseline survey carried out at Were Ilu, in southern Wello, one of the verification sites of the collaborative vertisol management project, 109 farmers were interviewed to indicate their average crop yields in good and bad agricultural years (Table 2) (Jutzi et al., 1987). Bad agricultural years were ones of very heavy rainfall leading to serious waterlogging. The surface drainage provided by the BBFs effectively changed a potentially bad season for crops planted on flatlands to a good one for both wheat and horsebeans, as shown in Table 3 (Getachew et al., 1993).
At Inewari, in the central highlands of Ethiopia, forming BBFs is the traditional manual method of preparing vertisols for cropping at a cost of some 60 hours of human labour per hectare. The BBM replaced the drudgery of constructing BBFs manually, which, in Inewari, was done mainly by women and children (Figure 5). It reduced the average manual labour required by 67 percent (Asamenew et al., 1993). Manually made BBFs are equally effective in draining excess water and hence crop yields are not significantly different from those attained by using the BBM. In years when the rainy season starts late, however, it is difficult to scoop the dry soil by hand. During such years, the BBM helped significantly to increase crop yields and economic benefits, even at Inewari (Asamenew et al, 1993).
2. Average yield expectations in good and bad agricultural years at Were Ilu, Ethiopia - Rendements moyens estimés du blé, du teff et des fèves dans les bonnes et les mauvaises années à Were llu (Ethiopie) - Previsiones del rendimiento medio en años agrícolas buenos y malos en Were Ilu, Etiopía
|
Crop |
Yield in good years (kg/ ha) |
Yield in bad years ( kg/ha) |
|
Wheat |
758 |
225 |
|
Tef |
651 |
297 |
|
Faba bean |
612 |
90 |
Source: Jutzi et al., 1987.
3. The broadbed maker - Machine à réaliser des sillons - Arado para construir platabandas de siembra
3. Drainage effects on grain and straw yields of wheat and horsebean at Were flu, Ethiopia, 1986 - Impact du drainage sur les rendements en grain et en paille du blé dur et de la fève à cheval à Were llu (Ethiopie), 1986 - Efectos del drenaje en los rendimientos de cereales y paja del trigo y el haba caballar en Were Ilu, Etiopía, 1986
|
Crop |
Land preparation |
Number of samples |
Grain yield (kg/ha) |
Straw yield (kg/ha) |
|
Durum wheat |
BBFs |
163 |
759* |
1 140* |
|
Traditional |
167 |
311 |
449 |
|
|
Horsebean |
BBFs |
170 |
683* |
572* |
|
Traditional |
166 |
172 |
162 |
Source: Getachew et al., 1993.
BBEs broadbeds and furrows, 120 cm wide.
Traditional - ridges and furrows, ridge 30 an wide.
*Diference between land preparation systems for each crop; significant at p<0.00 1.
The BBM also assisted in increasing vertisol productivity in the medium-altitude highlands, where crops are traditionally grown on flat plots. At Debre Zeit, for example, over a period of five years there was an average increase in net return of 32 percent from wheat production as a result of using the BBM (Asamenew et al, 1993).
In 1989, a small number of the latest BBMs were produced for on-farm verification by ILCA. By 1993, a local entrepreneur started producing BBMs, and, by 1995, more than 10 000 had been sold to individual farmers, non-governmental organizations and the Ministry of Agriculture. These implements are now being tested on vertisols in the central highlands for a variety of crops, including improved wheat varieties.
The concept
In many parts of rural Ethiopia, water is a scarce resource. Both people and their livestock travel long distances daily to obtain the water they need (Figure 6). As a result, animals suffer and productivity is reduced. Existing water supplies can be supplemented by improving water collection at spring sites, by constructing wells to tap groundwater or by collecting runoff in reservoirs. Constructing reservoirs using either manual labour or heavy earth-moving machinery may not be appropriate in rural areas because these methods can be very labour-intensive or expensive. The use of animal power to construct water reservoirs is an option in countries where draught animals are common. In rural Ethiopia, collecting runoff using animal power is a viable means of improving water supplies since the cost is low and within reach of the population. The provision of water reservoirs could contribute much to the intensification of agriculture by increasing overall crop and livestock production.
Research on pond excavation in Ethiopia
In Ethiopia, ILCA, in cooperation with the Ministry of Agriculture, has investigated the use of animal-drawn scoops for excavating new ponds and for desilting old ones to supplement dry-season water supplies.
The basic scoop design employed in the initial trials was similar to the Dutch horse-drawn mould-board and the British eighteenth-century levelling box (Branford, 1976). These European implements were designed to be drawn by large animals. A smaller version with a capacity of 0.15 m³ that could be pulled by a pair of Ethiopian zebu oxen was developed. Initial testing of this technology began in 1983 with the excavation of a 7 000 m³ pond on ILCA's research station in Debre Berhan, 120 km northeast of Addis Ababa (Astatke, 1984).
Two simple implements are required to construct a pond: a maresha and a scoop. The maresha is used first to break up the soil surface and the loosened material is removed with the animal-drawn scoop to a dumping site at one end of the pond. The maresha is then used again to break Up the subsoil, which in turn is removed by the scoop (Figure 7). The amount of time given to scooping depends on the size and condition of the draught animals and the friability and moisture content of the soil. At Debre Berhan, approximately ten hours were required to remove each 100 m³ of soil (Astatke, gunning and Anderson, 1986). The average draught power of a pair of local zebu oxen pulling a full scoop was 0.92 kW, which falls within the upper range of power needed for the first pass with the maresha (Astatke, 1984). Subsequently, the Ethiopian Ministry of Agriculture redesigned the scoop to reduce power requirements even further. The new models are about 15 percent smaller than the first prototypes and have two metal skids on the bottom to reduce friction. The scoops are robust, but if the wooden handles should break they can be repaired easily by the farmers themselves.
In 1985, two ponds of 9 500 m³ and 8 700 m³ capacity were constructed by two peasant associations using animal-drawn scoops. The farmers worked for about 75 days and employed 900 ox-pair days in total to construct each pond. On average, the oxen worked about six hours a day with a net excavation rate (including both ploughing and scooping) of 6.8 m³ of soil per pair per day (Anderson and Astatke, 1985). Pairs of oxen used for desilting existing ponds were able to excavate 13 m³ Of silt per five hours of work (Haile Selassie and Cossins, 1985).
Use of scoops in large-scale field operations
In 1987, approximately 1 300 scoops were distributed throughout the country. By 1988, farmers using scoops excavated 18 ponds in the northern and northeastern parts of Ethiopia under the supervision of the Ministry of Agriculture (Figure 8). However, there has been no evidence of the use of scoops for pond construction since 1988. The major problems experienced by the peasant associations when constructing ponds had been organizational. The Ministry of Agriculture lacked the resources and personnel to provide technical guidance at all locations. The frequency with which farmers brought their animals to work was not accurately planned to ensure that ponds were completed on time. This created difficulties for further excavation the following year, since it took some time before the dug area dried up sufficiently to allow work with animals to begin (Anderson and Astatke, 1985).
The scoops are simple but expensive when considering individual farmers' incomes. And since farmers cannot excavate ponds by themselves, scoops have to be acquired by the community. If the work is to be successful, considerable cooperation will be required within the community when planning, locating and constructing large ponds.
Traditional land use in the Ethiopian highlands can no longer support the present population. New production systems are needed to intensify land use for higher grain and livestock production. The multiple use of animals has a major role in changing the traditional production systems, which rely entirely on the use of oxen for draught power. The need to match appropriate breeds and implements with soil types and farm resources is a topic that will have to be resolved through research.
The use of appropriate animal-drawn implements, for example, enabled increased productivity of vertisols when tested in the Ethiopian highlands. This could serve as an incentive to curtail the movement towards cultivating steeper slopes, which are prone to I and degradation. Guided conservation of runoff in water reservoirs, excavated using animal power, could enhance crop and livestock production and, most important, locate the much needed water within easy reach for household use. How potential benefits of animal traction can be tapped on a countrywide scale by smallholder farmers to meet their immediate and future needs from agricultural production will be a definite challenge for policymakers.
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