Cereal harvesting – strategies and costs under variable weather conditions

This study simulated 30 years of harvesting operations on an hourly basis with a harvesting model linked to a grain moisture model capable of predicting the moisture content of standing ripe wheat using historical weather data from Stockholm, Sweden, as input, in order to assess the effects of weather on cereal harvesting costs. Several combinations of harvester size and grain moisture ceiling were assessed on three cereal areas in terms of overall costs (machine + labour + timeliness + drying) and their annual variations. The main findings obtained by simulation and valid for regions with similar climate and agricultural conditions to the studied region were that: (a) available combining time was highly dependent on grain moisture ceiling, which showed large annual variation, e.g. a moisture ceiling of 21% (w.b.) was related to a potential harvesting time of 65% and a standard deviation of 24% (n = 30 years); (b) in order to complete harvesting operations in most years, it was necessary to operate at a moisture ceiling of 22–24% (w.b.), however, the average moisture content of the harvested grain was much lower, about 17–18%; (c) overall harvesting costs were estimated at approx. €140 ha−1 for those systems performing relatively well, i.e. with a daily harvesting capacity of 4–5% of the cereal area and operating at a moisture ceiling of 22–24% (w.b.); and (d) the main sources of annual cost variation were firstly the timeliness costs and secondly the drying costs.