A group of students investigated soil infiltration rates across a sloping pasture. At each of four different elevations along a transect line, they drove a single-ring metal infiltrometer (diameter 10 cm) into the ground to a depth of 5 cm, poured in 200 ml of water, and recorded the total time taken for the water to fully infiltrate the soil. They took a single measurement at each elevation.
Suggest one way that this data collection method could be improved to increase the reliability or accuracy of their results.
