Abstract :
ABSTRACT: Each year a significant portion of the countryʹs wheat production wasted at different stages of production. One of the most important stages of product loss, it is Harvest stage. The first step in planning for waste reduction wheat harvest estimate the amount of losses and factors are identified. In this study during combine wheat harvesting in shahrood, 8 combines selected and evaluated. Results showed that, the mean of loss in 3 samples was 16.1 %. This amount is out of the acceptable range. The mean of combine total loss at wheat harvesting stage was 6.88 %. The most amount of waste belonged to combine harvester head (5.35%). Crop loss of combine end and natural loss were 1.24 % and 0.49 %, respectively. Harvesting delay and unadjusted combines are the most causes of crop loss. Thus the understanding of growers and combine operators about combine working and its adjusting is effective in loss reduction. Also, results showed that about 90% of the studied combines were more than 13 years old, but results showed that these combines had less loss than newer combines if their operators were skilled and they were adjusted properly. Annually cost of wheat loss in shahrood is more than 3 billions rials. However, combine adjusting is not the only factor to reduce loss. Many factors, such as combine abrasion or management and planning factors are affecting crop loss. Time of harvesting, seed moisture content, weather relative humidity, field topography, correct combine performance and crop characteristics identification are affecting crop loss reduction
