Compaction Effects of Green Vegetable Harvester Fitted with Different Running Gear Systems and Soil-Machinery Relationship

In this research, the traffic effects on some physical parameters and crop yield following the traffic of self propelled harvesters on clay soil with water content at 0.88 of field capacity was evaluated. A clay-tyre-track numeric index to predict trafficability was developed. Field tests were carried out using two green vegetable harvesting equipments: one articulated (135 kW engine power) fitted with two different running gear arrangements: four wheel-drive, four rubber track and the same four rubber track with low lugs and one (120 kW engine power) fitted with metal track on a cultivated soil with spinach. Results shown that harvesters pass with the different running gear caused significantly effects on the soil with regard to the studied parameters. Increases of penetration resistance over the control in the upper layer (0-0.10 m) was higher for rubber track (0.34), while from 0.11 to 0.30 m depth were lower for metal track (0.36). In these soil layers, increases of shear strength over the control were lower for wheel track (0.13). According with penetration resistance values, increase of bulk density over the Control was higher for rubber track (0.22). Total porosity and yield of spinach should be considered as being significantly influenced with a decrement ratio respect to the control around 0.50, in the treatments involving wheel and rubber track. For the soil layers (0-0.20 m depth), significant correlations between measured penetration resistance and water content, penetration resistance increases over the control after machinery pass and clay-tyre-track numeric index for the different type of vehicles tested and soil texture, were found. However, in the soil layers examined, with respect to the behaviour of studied parameters and trafficability index, treatments involving harvesters fitted with metal and rubber track with low lugs showed a lower degree of soil compaction particularly below 0.10 m depth.