Local officials are concerned that agricultural fields at site B are increasing sedimentation in the river because of soil erodi
ng from the fields. They hire an environmental consulting company to perform a study to determine if this is true. The company marks out two one-hectare plots at point B and point C in the diagram. The characteristics of the land in both plots are identical except that plot B is covered by agricultural fields and plot C is covered by undisturbed forest. Rain gauges are set up at the up-slope edge of the plots, and devices that collect eroded soil are set up along the down-slope edge of the plots. The environmental consultants hypothesize that more soil will be eroded from plot B than from plot C. Data are collected at the rain gauges and soil-collection devices at the end of each month for a year. (i) Identify the dependent variable in the study.
(ii) Describe how plot C serves as the control in the study.
(iii) Both plots received a total of 116cm of rainfall by the end of the year as measured by the rain gauges. By the end of the year, a total of 200kg of soil was collected from the plot B soil-collection devices and a total of 200kg of soil was collected from the plot C devices. Describe a practice or agricultural method that could have been used at plot B to obtain these results.
(iv) The results of the study could be altered if there were changes to the land surface in the area of plot B and plot C. Identify and describe one characteristic of the land surface in the plots that could be altered to decrease the amount of erosion in both plots.
