Fertilizer Best Management Practices: A Perspective from the Dryland West Asia-North Africa Region

Chemical fertilizer use has contributed significantly to increased global food output in the past half century, especially in climatically favourable regions of the world. However, in drier agro-ecological zones, such as in West Asia and North Africa (WANA) with a Mediterranean-type climate, fertilizer use has been low but has increased rapidly in the past few decades. Chemical fertilizer use is now widely adopted in rainfed and irrigated agriculture. As elsewhere, fertilizer use is underpinned by concerns about biological and economic efficiency. Fertilizer use efficiency is central to the current concept of fertilizer best management practices (FBMP), which embraces right source, right place, right timing and right application method. In this brief review, we highlight such FBMP concepts as related to agriculture of the WANA region, with emphasis on the key nutrients for crop production. Rainfall has a dominant influence on dryland crop yields. Nitrogen (N) use efficiency increases with increasing rainfall and is influenced by crop rotation. Under rainfed conditions, modest N losses by volatilization can occur. Leaching losses are usually minimal. Phosphorus use (P) efficiency is higher with band application than with broadcasting. Balanced fertilization, especially involving potassium (K) and micronutrients, is fundamental to efficient nutrient use. Fertilizer efficiency is also influenced by soil test values and agronomic factors that influence crop yields, e.g. sowing date and varietal differences. Rational fertilizer application rates are guided by calibrationresponse trials. Effective fertilizer use in the region is also dictated by external factors such as government policies and a functioning extension service. In contrast to other regions of the world, environmental impacts from the overuse of fertilizers are relatively minor, while developments in fertilizer formulations that promote efficiency have yet to have impact. Despite the relatively low fertilizer use intensity in dryland areas such as the WANA region, the FBMP comprehensive approach is a logical framework within which to achieve the most efficient management and use of fertilizer in the regions agriculture.