changes in soil physical properties in response to metal-tracked skidder traffic

ground skidding on skid trails affects the physical properties of soil. the objective of this study was to evaluate changes in soil physical properties on skid trails formed due to traffic of metal-tracked skidders with regard to soil bulk density, total porosity, water content and penetration resistance. the studies were implemented on two levels of slope – 20% (sc2) – and three levels of traffic (one, five and nine traffic cycles). the treatment plots with three replications, consequently, were 6 m long and 4 m wide. the measurement of soil penetration resistance was carried out using a cone penetrometer. the samples were taken from 10 cm of top soil at six points in each plot. the results indicated that the skidder traffic did not significantly affect the soil physical properties measured in three levels of traffic at sc1, whereas it was significant between one and five traffic cycles in sc2. most of the changes in the measured properties in the skid trails occurred after the first loaded skidder traffic. within all traffic of sc2, differences in the mean values of water content and soil porosity were greater compared with the mean values at the same traffic of sc1, although these differences were not significant. the bulk density and penetration resistance at five and nine traffics of sc2 were significantly different from the same traffic of sc1.