Machinery maneuvering efficiency and perennial crops: Field shape complexity defines the efficiency

Perennial crops can serve as a feedstock to produce biomaterials and biofuels while enhancing soil and water quality. Perennial crops can provide income from the biomass produced while also delivering valuable ecosystem services. Planting perennial crops benefit the farmer if placed along streams, on steep hillsides, and other environmentally vulnerable areas of a field. However, planting perennial crops in these vulnerable areas may result in complex field shapes which can decrease the machine routing efficiency reducing the economic benefits. Such decrease in logistic machinery efficiency reflects the more time spent on the field and the higher operation cost. This paper analyzed the time series data from switchgrass harvesting operations to show the correlation between field shape descriptors and machinery efficiency. By conducting regression analysis between field area and boundary shape descriptors, and the ratios between working time and total time in the field, we could show the relationship between machinery efficiency and the descriptors. The curb index served as a useful predictor of machinery efficiency and can be used to predict field efficiency based on field geometry, equipment coverage width, and the number of headland passes when empirical data cannot be collected. Such correlation is vital to calculate the cost of perennial crop machinery operations, and thus to estimate the cost-effectiveness of such crops in an integrated landscape design. The established relationship can be used in farm techno-economic analysis, as well as in designing fields that maximize the machinery efficiency given the field shape and in-field obstacles.