ملخص
The research aims to estimate the functions of production costs, to determine the profit-maximizing size, and the economically efficient size, that lower average costs of production, and achieve economic efficiency. It also determines some of the most important indicators of profitability of barley crops under the conditions of irrigated agriculture in the East Bani Waleed region. The research depended on the econometric and statistical analysis of the primary data which was collected by questionnaire and personal interviews for a random sample, that included (41) barley farms as a main crop during the agricultural season 2017/2018.The results of the cost structure analysis of the barley production showed that the variable costs accounted approximately (63.92%) of total cost, while the fixed costs accounted (36.08%) of the total costs. Also the results of the research showed that the profit-maximizing size reached (33.29) tons per farm for the all research sample, while it is estimated at (23.5), (36.5) tons for farms of the first and second categories respectively. The optimum size of production for the all farms of the research sample was estimated at (25.89) tons and (20.2), (30.5) tons for the first and second categories respectively. The results also indicated that the economically efficient acreage size was (13.02) hectares for the all farms of the research sample, and (6.5), for the first category while it is estimated at (16.0) hectares for second category, which was not far from the actual acreage of this category, and the cost elasticity was estimated at (0.91) for the second category. Furthermore the minimum price (break-even price) was calculated at (1046) LDs/tons for all farms of the research sample, (1093) and (951) LDs/tons for the first and second categories respectively, and net profit was estimated at (493.7) LDs/h. for the total sample, and (409.2) , (656.4) LDs/h. for the first and second categories, respectively. The technical efficiency was estimated at (92.4%) for second categories, which largest acreage compared to (43.3%) for the first category with the lowest acreage. Keywords: Irrigated barley cultivation, cost function, economic efficiency, Bani Waleed region.