ABSTRACT
Chapter 4 MARESHA MODIFIED IMPLEMENTS FOR CONSERVATION TILLAGE3 4.1 Overview Appropriate tillage implements are often the primary concern when shifting from conventional tillage to conservation tillage. In mechanized agriculture shifting to conservation tillage is usually accompanied by abandoning plows and harrows and introducing sprayers for the application of herbicides as it has been found that use of herbicides were more economical than mechanical tillage with tractors due to rising fuel costs (Derpsch, 1998). On the other hand, under smallholder farming systems use of herbicides for weed control has not been feasible (Ofori, 1993; Muliokela et al., 2001). Under hoe culture, shifting to conservation tillage system requires the adoption of animal traction as the implements required for conservation tillage are mostly animal drawn. In Ethiopia, a large number of farmers use oxen for tillage (Pathak, 1987). However, the traditional oxen drawn implement, the Maresha plow, has been found to force farmers to undertake repeated and cross plowing, which causes land degradation (Chapter 3). Therefore, there is a need to come up with improved implements that can undertake conservation tillage systems without being too expensive, too heavy and too sophisticated for the resource poor smallholder farmers in semi-arid regions of Ethiopia. Animal drawn implements developed to undertake conservation tillage under smallholder farming systems include the Palabama Subsoiler and the Magoye ripper (Jonsson et al., 2000; Muliokela et al., 2001). These implements were developed as attachments to the mould board plow frames that are too heavy and unaffordable by smallholder farmers in Ethiopia (Goe, 1987; Temesgen, 2000). In this chapter, different types of conservation tillage implements, which were developed as modifications or attachments to the traditional tillage implement, the Maresha plow, are presented. The results of testing their performance on farmers’ fields are reported. 4.1.1 The Maresha plow - Opportunities and Drawbacks Farmers in Ethiopia have used the Maresha plow (Figure 1.4) for thousands of years (Goe, 1987). It is very simple, light in weight, cheap, and locally made. However, as a conventional tillage implement, the Maresha plow has got several drawbacks which arise mainly from the fact that the plow forms V-shaped
furrows and results in incomplete plowing (Chapter 3). These drawbacks can have the following effects. 1. Because of incomplete plowing, farmers have to do repeated tillage in order
to produce a fine seedbed especially for tef. As a result, the soil is excessively pulverized resulting in a poor structure (crust formation, compaction, etc.)
2. Because of the V-shaped furrow formed by the Maresha plow it is necessary that every two consecutive tillage operations are oriented perpendicular to each other. Thus, in inclined fields one of the two plowing operations fall along or nearly along the slope. The furrows encourage runoff when they are laid along the slope (Edwards et al., 1993 and Basic et al., 2001). This is a very serious problem in Ethiopia because the country is very hilly resulting in large amounts of soil and water loss.
