Tesfay Araya

The Use of the Marasha Ard Plough for Conservation Agriculture in Northern Ethiopia

Indigenous tillage systems are often undervalued in conservation agriculture (CA). In Ethiopia, since the 1970s there have been several attempts to develop and implement often major modifications to the marasha, the traditional ox-drawn ard plough, with the main aim of creating various types of surface depressions. The establishment of furrows and ridges increases soil moisture and grain yield and reduces soil loss. Dissemination of the modified tools, however, remains limited. Recent tendencies are towards testing relatively simple conservation agriculture tools. Major challenges remain, however; the need for capacity building and problems in marketing the tools. From experimental plots, often worked with exotic tools, there is a long road to real adoption by farmers. Rather than developing yet another CA tool, we investigate whether CA-based resource-conserving technologies might be achieved successfully with simple changes to the use of the marasha. On-farm observations on traditional conservation techniques were carried out throughout the northern Ethiopian highlands, and experiments were conducted involving resource-conserving technologies. Farmers traditionally use the marasha ard plough for various types of in situ soil and water conservation by creating surface depressions, either at the moment of sowing (terwah, derdero) or after crop emergence (shilshalo). Building upon this indigenous knowledge, we further developed resource-conserving technologies into a system named derdero+, whereby the traditional ard plough was found suitable for a “bed-and-furrow” system. From the socio-economic point of view, implementation of permanent beds and retention of stubble leads to decreased oxen (and straw) requirements, but also to an increased need for weeding in the first years. To overcome that problem, we introduced glyphosate herbicide into the tillage system. The decreased runoff (−51%) and soil loss (−81%) allow protection of the downslope areas from flooding, but soil nutrient build-up and soil structure improvement are slow processes, and hence the full benefit of the permanent bed system can only be expected after some years. Overall, this type of resource-conserving technology can be part of the ongoing intensification process which includes physical soil and water conservation, slope reforestation and irrigation development. It has, however, its own niche: the cropped land sensu stricto, i.e. the most important part of the land, both for the farmer and for a nation that is striving for long-term food security.

RESTORING CROPLAND PRODUCTIVITY AND PROFITABILITY IN NORTHERN ETHIOPIAN DRYLANDS AFTER NINE YEARS OF RESOURCE-CONSERVING AGRICULTURE

Long-term in situ soil and water conservation experiments are rare in sub-Saharan Africa, particularly in Eastern Africa. A long-termexperiment was conducted (2005–2013) on aVertisol to quantify the impacts of resource-conserving agriculture (RCA) on runoff, soil loss, soil fertility and crop productivity and economic profitability in northern Ethiopia. Two RCA practices were developed from traditional furrow tillage practices: (i) derdero+ (DER+) and terwah+ (TER+). DER+ is a furrow and permanent raised bed planting system, tilled once at planting time by refreshing the furrow and 30% of crop residue is retained. TER+ is ploughed once at planting, furrows are made at 1.5 m intervals and 30% crop residue is retained. The third treatment was a conventional tillage (CT) with a minimum of three tillage operations and complete removal of crop residues. Wheat, teff, barley and grass pea crops were grown in rotation. Runoff, and soil and nutrient loss were measured in plastic sheet-lined collector trenches. Significantly different (P < 0.05) runoff coefficients (%) and soil losses (t ha−1) averaged over 9 yrs were 14 and 3, 22 and 11 and 30 and 17 for DER+, TER+ and CT, respectively. Significant improvements in crop yield and gross margin were observed after a period of three years of cropping This study demonstrated that RCA systems in semi-arid agro-ecosystems constitute a field rainwater conservation and soil fertility improvement strategy that enhances crop productivity and economic profitability. Adoption of RCA systems (DER+ and TER+) in the study area requires further work to improve smallholder farmers’ awareness on benefits, to guarantee high standards during implementation and to design appropriate weed management strategies.

Toward Practical Implementation of Conservation Agriculture: A Case Study in the May Zeg-zeg Catchment (Ethiopia)

Conservation agriculture (CA) is often quoted as a beneficial resource-saving technique for dryland agriculture, but its large-scale implementation is frequently hindered by the lack of farmers’ acceptance. To date, few studies have investigated the impact of spatial factors, costs and benefits and regional agroecosystem differentiation on adoption of CA. This study, therefore, aims to assess the impact of these factors through a case study in the North Ethiopian Highlands. One hundred eight farmers of 11 villages surrounding an experimental plot were interviewed in order to identify their knowledge and acceptance of the technique. The results show that several spatial factors play a role in CA acceptance. The lack of knowledge on the resource-saving technique proved primarily dependent (R = –0.73) on spatial impedance with the innovation source and on the strength of sociospatial networks. Next, a consumer model showed that perceived costs and benefits seem to balance each other. Finally, some agronomic traditions were identified that are related to the regional agroecosystem, which are not favoring the implementation of zero-tillage practices. Since this study identified acceptance problems related to several spatial and regional factors, future CA adoption schemes must allow better regional differentiation optimized to local contexts and conditions.

Source of mycorrhizal inoculum influences growth of Faidherbia albida seedlings

Poor land use management and practice inhibit the growth and establishment of tree seedlings in dryland areas. We assessed arbuscular mycorrhizal fungi (AM) status of Faidherbia albida (Del.) A. Chev. trees grown on different land uses. We quantified the growth and nutrient uptake of F. albida seedlings inoculated with AM from different sources. These efforts were based on soil and fine root samples from the rhizosphere soils of F. albida trees. AM root colonization was determined using the gridline intersect method. Spores were extracted by the wet sieving and decanting method and identified to genus level. The seedling experiment had a completely randomized one-factorial design with four treatments and five replications. Faidherbida albida seedlings were grown in a greenhouse. All in situ F. albida trees were colonized by AM fungi. AM root colonization of F. albida trees was significantly higher (P < 0.0086) in area exclosures than on lands used for grazing or cultivation. Spore abundance was significantly higher (P < 0.0014) in area exclosures followed by cultivated land and grazing land. Glomus was the dominant genus in all land-uses. AM-inoculated F. albida seedlings grew better (P < 0.05) than non-inoculated controls. Seedlings inoculated with AM from area exclosure had significantly (P < 0.05) higher growth and nutrient uptake than those inoculated with AM from grazing and cultivated land. This emphasizes the importance of the native soil AM potential for better establishment of seedlings to achieve optimum plant growth improvement and assist in rehabilitation of degraded arid lands.