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Smallholder farmers in Ethiopia practice traditional tillage systems using an ard plow called Maresha. Traditional tillage systems that involve repeated cultivations with the Maresha plow have caused land degradation (a.o. formation of a plow pan) and poor utilization of rainwater that led to low crop productivity. Experience in other countries has shown that conservation tillage systems could improve utilization of rain water through increased infiltration. However, the implements used for conservation tillage in other countries were found to be too heavy and too expensive for smallholder farmers in Ethiopia. On the other hand, lighter and low cost implements have been developed in Ethiopia as modifications to the Maresha plow. These implements are the Subsoiler, the Tie-ridger, and the Sweep. Field tests were carried out to evaluate the modified implements and a rip plant type of conservation tillage systems using the modified implements. The results showed that the Subsoiler reached a depth of approx. 24 and 27 cm after 1 resp. 2 passes through the furrow made by the Maresha, and thus was capable of disrupting the plow pan. Compared to the Maresha plow and the inverted broad bed maker (BBM), the Tie-ridger required less draft power (79 kg vs. 96 for the Maresha and 103 for the BBM) and lower lifting force (-43%) while forming furrows with larger (+36 resp. +15%) cross-sectional areas. The Sweep enabled deeper root growth of tef (Eragrostis tef (Zucc.)) apart from accomplishing sowing operations faster (+50%). It is concluded that the newly developed implements are suitable to undertake conservation tillage under smallholder farming systems in the semi-arid regions of Ethiopia. The rip-plant type of conservation tillage systems, however, was not found to be viable for maize (Zea mays) production under the study conditions in which loss of soil moisture through evaporation is high. Both grain and biomass yields were highest in the conventional systems, although differences were statistically not significant. On the other hand, a reduced tillage system tested on tef resulted in higher grain yields as compared to conventional tillage. (C) 2008 Elsevier B.V. All rights reserved.