CROP RESPONSE TO IMPROVED DRAINAGE OF VERTISOLS IN THE ETHIOPIAN HIGHLANDS

The effect of flat seedbed, traditional ridge and furrow and improved drainage of broad bed and furrow (BBF) on grain and straw yield of dur um wheat, chickpea and lentil at several Vertisol sites between 1988-1 991 was such that on three crops the BBF system gave the highest grain and straw yields at all locations and seasons. This was followed by t raditional ridge and furrow system and the least yield was obtained fr om flat seed beds. The extent of drainage influence on yield was depen dent on rainfall quantity, location (clay content) and crop species. T he advantages of the BBF technology in improving drainage and increasi ng crop yield are discussed in their contexts of better cropping syste ms.