Workability and Machinery Sizing for Combine Harvesting

Abstract

Harvesting costs make up 30 % of overall in-field machinery costs. In addition to this, indirect machinery costs may be incurred through timeliness effects, i.e., reduction in crop yield and quality caused by inefficient scheduling of machinery operations. Optimal work organization and machinery utilization are essential elements in achieving cost reductions, requiring detailed quantifications of harvesting workability and machine performance. This study has adapted models predicting harvesting workability as governed by the crop moisture status. The hourly course of grain moisture status after maturity was simulated for a 30-year period, allowing for the prediction of the number of workable harvesting hours under different weather conditions, at different moisture thresholds, and for different localities. A farm-level optimization model has been used to depict the potential effects of different economic-incentive options. Results show that the utilization coefficient, expressing the potential harvesting time as a fraction of total daytime, varies considerably depending on the type of crop and moisture thresholds, e.g., ranging across types of crops from an average 21 to 36 % for the 18 % moisture threshold. Additionally, indications are that winter barley may permit 15–25 % more harvesting hours than spring barley. The influence of the geographical locality indicates 15–40 % higher utilization for western Denmark than for eastern Denmark due to climatically differences. Independently maturing crops, dispersion of maturing periods, harvesting time, and in-field machinery efficiency all affect work organization and optimal machinery size and may reduce the capacity demand and costs considerably.