A new agro-climatic classification for crop suitability zoning in northern semi-arid Ethiopia

The agro-climatic resources of Giba catchment in northern Ethiopia were assessed and characterized. The objectives were (i) to ascertain the suitability of the climate for growing teff (Eragrostis tef) and barley (Hordeum vulgare); (ii) to determine the onset and length of the growing period (LGP), (iii) to evaluate the traditional method of climate classification, and (iv) to produce comprehensive agro-climatic zones of the Giba catchment. The Ethiopian traditional method of climate classification based on temperature and altitude was found to be less relevant to crop suitability zoning in semi-arid regions of Northern Ethiopia because within this semi-arid drought-prone environment the rainfall is more important for crop growth than temperature. The LGP ranges from 60 to 100 days over the catchment, increasing from north-east to south-west. For the crop suitability zoning, the concept of growing period was introduced into the traditional approach, to produce agro-climatic zones. This method could be used to develop agronomic strategies to cope with the anticipated increase in drought in the semi-arid tropics under climate change. Accordingly, quick maturing and drought-resistant varieties of teff and barley can be grown in the centre and in the east, while medium-maturing cultivars should do well in the south-west. The method requires limited input data and is simple in its use.