Abstract :
The objective of this study was to analyse the influence of daily weather on timeliness costs of field machinery on cereal farms in Sweden while varying its size, number of drivers, farm size and location. A discrete event simulation model with the capability to simulate daily field operations on a farm for a series of years was linked to a soil model to infer daily soil workability. Completion dates of operations for individual fields and years were utilised to quantify annual timeliness costs in detail for 15 or 20 yr.
Timeliness costs were an important part of total costs and ‘least-cost’ sets, i.e. those sets with the lowest sum of specific machinery+labour+timeliness costs, were situation-specific, they varied from a low value to more than €150 ha−1. Within certain limits of machinery capacity and for a given farm, there was not only one set identified as the ‘least-cost’ set but several. Sets with high daily effective field capacity showed low annual variation in timeliness costs; the effects of decreasing capacity on timeliness costs were not linear because an increasing number of fields were left uncultivated or partially cultivated, making timeliness costs difficult to predict. The machinery set to be selected should be the largest one among those with similar ‘least-cost’ on account of its lower annual variation, which in turn should lead to lower risks.
