Quantifying the Impact of Off-Road Driving on Root-Area Distribution in Soils

Studies on the effects of off-road driving on soils were conducted in the Makuleke Contractual Park of the Kruger National Park. The studies were conducted on three different soils with different textures and soil compactibilities. Traffic pressure was applied with a game drive vehicle loaded with 10 sand bags, each weighing 70 kg, plus the driver. This gave a total vehicle mass of 3795 kg, simulating a vehicle fully laden with tourists. The results of the study reported here included comparing of the effects of four different tyre pressures on the root area distribution below each tyre pressure. At all sites, root density fractions under the tracks were reduced significantly at all tyre pressures, compared with the control values. Results indicated that root penetration percentage and root area distribution were reduced drastically as tyre pressure increased. Our work reaffirms previous research showing that higher tyre pressures cause higher sub-soil compaction than lower tyre pressures. Thus, driving with lower tyre pressures when driving off-road should be considered when developing management strategies for off-road driving in wildlife protected areas.