Short-term effects of conservation tillage on soil (Vertisol) and crop (teff, Eragrostis tef) attributes in the northern Ethiopian highlands

A conservation agriculture (CA) experiment was conducted in 2006 at Adigudom, Tigray, Northern Ethiopia, on experimental plots established in 2005 on a farmer’s field. The objectives of this experiment were to evaluate the short term changes in soil quality of a Vertisol due to the implementation of conservation agriculture practices and to assess their effect on runoff and soil loss (not reported here), crop yield and yield components of teff (Eragrostis tef (Zucc.) Trotter). The treatments were permanent bed (PB), terwah (TERW) and conventional tillage (TRAD). Soil organic matter (SOM) was significantly higher in PB (2.49 %) compared to TRAD (2.33 %) and TERW (2.36 %). Although aggregate stability of PB (0.94) was higher than TRAD (0.83), the difference was not significant. PB had larger macroporosity (0.07) compared to the other treatments. The other soil physical quality parameters analysed showed, however, inconsistency between treatments. Moreover the plant available water content of all treatments was similar. Despite the above soil physical properties improvements, which most probably resulted in higher soil water storage in PB than in the other treatments, yield, biomass and plant height of teff were significantly higher in TRAD than PB. The significantly high weed dry matter at first weeding in PB, the types of weeds and their water uptake behaviour may have caused the reduced teff yield. Herbicides must be used while growing teff in CA experiments