What is the purpose of contour farming?

The purpose of contour farming is to reduce erosion on slopes by plowing across them. This agricultural practice involves tilling and planting across the elevation contours of a slope instead of down the slope. By following the natural lines of the land, contour farming helps to create natural barriers that slow down water runoff, allowing more water to infiltrate the soil and reducing soil erosion. This is particularly important in hilly or sloped areas, where conventional farming methods could lead to significant soil loss and degradation.

The other options, while they address different aspects of farming, do not capture the primary objective of contour farming, which is focused on soil conservation and erosion control rather than merely improving crop yields, water usage, or ease of planting in flat areas.