Spatial analyses of field traffic intensity and modeling of changes in wheel load and ground contact pressure in individual fields during a silage maize harvest

One of the key measures for preventing harmful soil compaction in agricultural fields is to reduce of the intensity of field traffic. This holds especially true for field traffic with a high wheel load, which is typical for harvest operations. The aim of this study was to model the spatial patterns of traffic intensity as related to soil compaction in a silage maize field during harvest, taking into account the changes in wheel load and mean ground contact pressure along the single loading sections. Based on GPS data that was recorded for each farm vehicle employed on the study fields and on the respective vehicle characteristics (such as axle width, tire type and size, and machine weight), the percentage of ground area wheeled at a specific load and contact pressure has been calculated using a Geographic Information System (GIS). The results of this study reveal that almost 62.8% of the field area had been wheeled by the harvester and the transportation vehicles. About 66% of the total wheel track area had been rolled over more than two times. Nearly 48% of this area had been wheeled at least once with a maximum mean ground contact pressure that exceeded 87 kPa. Regarding the wheel load, it was found that about 43.8% of the field area had been wheeled at least once with a maximum wheel load between 50 and 62.5 kN. The wheel track patterns modeled for the transport vehicles have been subdivided into route sections used under full and empty load and during loading in order to detect unnecessary traffic related to each of these sections. Spatial analysis identified the courses and lengths of the return routes of fully loaded transport vehicles as the main routes of (avoidable) soil stress caused by high wheel loads and high ground contact pressures. More than 50% of the return routes covered a distance >175 m. This could be reduced by optimizing the length of harvest sections as well as by rearranging the field geometry.