Nitrogen Fertilizer Response of Some Barley Varieties in Semi-Arid Conditions in Morocco

The west asia-north africa region, which is characterized by a typical mediterraneanclimate, is the center of origin of cereals, notably wheat (triticum spp.) and barley (hordeumspp). however, cereal production, which is primarily rainfed, is mainly constrained bydrought due to the low rainfall accompanied by high temperatures. cereals have been traditionallygrown following a fallow period in order to achieve acceptable yields on stored soilmoisture, but they are increasingly grown either continuously or in rotation with legumes,either food or forage. barley is grown throughout the mediterranean region, generally inthe drier zones and often on shallow soils and with application of minimum or no fertilizers.the medium-rainfall zone of central morocco (200-500 mm yr-1) is typical of the region as awhole. in order to provide a rational basis for barley fertilization, especially as regards nitrogen(n), a field trial was established near settat, involving five barley varieties (acsad-60, tessaout, asni, arig-8, and acsad-176), along with four n application at four levels (0,40, 80, and 120 kg n ha-1), grown on a shallow soil (petrocalcic palexeroll) for two growingseasons that varied in terms of total rainfall (year 1, 261mm and year 2, 302 mm) as well aswithin-season distribution. there were considerable differences between crop years, withsignificantly higher yields in the second growing season when rainfall was heavy at the criticaltillering and stem-elongation growth stages. nitrogen consistently increased dry matterand grain yields in either year, generally being significant up to 80 kg ha-1. there were significantdifferences observed among varieties, as well as interactions of varieties with years.the six-row variety arig-8 was consistently the best while the two-row asni, the lowestyielding variety. where an economic analysis was done on yield data (year 1), n fertilizationup to at least 80 kg ha-1 was considered as profitable. crop n uptake varied with varietiesand increased with increasing fertilizer. n recovery was variable and generally less than50%. in contrast to many other fertilizer trials with barley in the region, this trial from centralmorocco showed highly significant yield increases in response to applied n for barleyvarieties, most of which performed similarly. therefore, n fertilization of barley in morocco’ssemi-arid cereal-producing zone on shallow soils, where root growth and moistureholdingcapacity are limited, should be promoted.