3 years by efforts of the Zambia National Farmers Union (ZNFU) Conservation Farming Unit in the Southern province of Mazabuka as reported by Aagard and Gibson, (1996). Zambian links with Hinton Estates in Zimbabwe culminated in ten commercial farmers establishing 20-70 ha under conservation tillage with encouraging results. Since December 1995, the conservation farming unit was established to promote conservation tillage in both large and small scale farming sectors. Some work on the promotion of various animal drawn rippers which have been extensively tested with farmers through extension brochures is in progress through a programme known as Smallholder Agricultural Mechanisation Promotions (SAMeP).
In Botswana it was reported (Nyagumbo, 1998) that tillage research has been undertaken since 1970s. However up to the present the most common form of tillage practise is mouldboard ploughing carried out on the day of planting. More recent research on different tillage methods (Persuad et al., 1990) recommends two methods namely double ploughing i.e. spring ploughing followed by another ploughing at planting and spring ploughing followed by tine cultivation at planting. Some work was also carried out on strip tillage on sandy loam soils and shallow tillage or herbicides on vertisols as reported by Willcocks and Twomlow (1991).
Ngoros (a series of pits 2.4m long x 2.1m wide x 0.14 – 0.30m deep) and the Matuta ridge systems (vegetation slashed and aligned across the hillsides and buried with soil thrown down-slope (Temu and Bisanda, 1996). These techniques have shown immense benefits in terms of soil and moisture conservation for crops as well as fertility improvements.
In Kenya the traditional conservation technique is the fanya juu terrace. In a recent study on traditional techniques mobile trash lines at 1.5- 7.5m spacings significantly out-yielded (maize and cow pea) and reduced soil loss and run-off levels compared to the control (Okoba et al., 1998). The use of these trash lines in combination with static structures such as fanya juus and stone bunds is a recommended system especially for lower Embu in eastern province.
3. Socio-economic issues of conservation tillage
Apart from the many technological concerns and proven gains of conservation tillage, the few exposed farmers in the region are still not adopting the techniques en masse. The non- technical reasons for the low adoption rates range from costs of equipment when they are available to the socio-cultural features such as fear of change and weaknesses in promotion and qualities of extension services.
In Malawi the ridging constructed by handhoes is the most common practise used by about 95% of the smallholder farmers (Mwinjilo, 1992). Zero tillage or no-till are not used at all due to cost of herbicides and lack of draught and labour resources (Kumwenda, 1990). Some effort is being made to reduce labour requirements for construction of ridges by the use of permanent ridges as compared to annual ones. Other forms of conservation practices include maize-legume inter-crops and rotations.
In Southern highlands of Tanzania 95% of the farms are less than 5 ha in size. Land preparation is mostly manual (Ley, 1990). In addition to standard mechanical structures such as channel terraces conservation tillage systems are in use with implements capable or retaining 70% crop residues on the surface after tillage operation. Weed control is achieved with the use of herbicides such as round-up. Problems cited included lack of appropriate machinery, experience and grazing of stover by livestock.
Traditional techniques locally developed in the southern highlands of Tanzania and suitable for use on steep slopes include the Matengo pit or
Socio-economic issues of conservation tillage in ESA centre around the traditional African customary approach to issues revolving around land its use and ownership. The value attached to land as a sign of worth and wealth can be a major source of caution, if not conflict in development.
Nyagumbo (1997) analyzed the socio-cultural constraints of smallholder technological dissemination and their impact on development projects. The observations were centred around the Contil project in Zimbabwe, which had faced varying degrees of success. It was observed that:
Farmers were victims of a receiver mentality, brought about by previous government and donor subsidized projects. They immediately lost interest each time they were told that the project had nothing to offer materially or financially. Longer term gains were more difficult to comprehend. Previous subsidies had been such as interest- free money to commence projects, with little contribution from the locals themselves.
This paper is published in: Kaumbutho P G and Simalenga T E (eds), 1999. Conservation tillage with animal traction. A resource book of the
Animal Traction Network for Eastern and Southern Africa (ATNESA). Harare. Zimbabwe. 173p. A publication supported by French Cooperation, Namibia. For details of ATNESA and its resource publications, see http://www.atnesa.org