Pastures, permanent crops, woods, hedges and paths are considered environmental cover, while mainly arable land and crops are not. Because satellite images allow for the interpretation of agricultural parcels, compliancy can be easily detected. Photo interpretation by remote sensing speeds up the process and allows many parcels to be checked in one time.
Tillage practices are also important for reducing erosion as they can reduce the runoff of water across the land surface. The GAEC stipulates that farmers have to plough or plant parallel to contour lines to avoid erosion on slopes more than or equal to a certain percentage defined by the country (e.g. slope of 10 percent).
By detecting parcels within this slope range, detecting the slope direction and the ploughing or planting direction, it is possible to calculate the angle between the slope and ploughing direction, taking into account the soil-sensitivity to erosion, and determine whether the farmer is compliant.
In order to receive subsidies for permanent crops, the GAEC requires that farmers properly maintain them. Using VHR images, the distinction between crops that are maintained good and crops that are possibly maintained badly can be detected, allowing authorities to visit the fields in question to detect whether they are abandoned or neglected.