تعیین اندازه بهینه اقتصادی ماشین های کشاورزی در مزرعه دانشکده کشاورزی شیراز: با استفاده از یک مدل مبتنی بر برنامه ریزی غیرخطی عدد صحیح

Abstract

Selection of optimal sizes of machinery and their proper investment are the main problems in the agricultural machinery. This study has done to optimize machinery sizes in agricultural college farm of Shiraz university. The crop plan includes: 130 ha wheat, 70 ha rapeseed, 100 ha corn, 25 ha alfalfa and 4 ha coloured. A nonـ linear mixed integer programming model is used to minimize total annual costs includes: fixed costs, variable costs and timeliness costs. This model implemented by using General Algebraic Modelling System (GAMS) software. Results show that machinery sizes simulated by model for operating width and load capacity are significantly different from actual sizes that used in sample farm and just sprayer and trailer sizes are as same as 400 and 4000 kilogram load capacity. Some sizes suggested larger and some smaller. For tractor suggested 8 number but greater power 85 hp/each. Non- agreement between optimal sizes and actual sizes shows different between optimal costs and actual costs. So that optimal total annual costs per hectare are less than actual total annual costs per hectare. Also operations schedule provided in various weeks of the year, that shows operations distribution in the course of time. This is a good guide for farm director to do operations schedule.