In a desert region, soil erosion can be a major concern due to the lack of vegetation and intense climate conditions. Option 1, tree plantation or afforestation, is an effective way to combat soil erosion in such areas. Trees help bind the soil with their roots, preventing it from being washed away by wind or water. Their canopy also provides shade, reducing the impact of rainfall or sunlight on the soil. Option 2, crop rotation, may not be as effective in a desert region because the availability of water is limited and the soil may not be suitable for sustained crop growth. Option 3, contour ploughing, involves creating furrows or ridges along the contour of the land to slow down water flow and prevent soil erosion. Option 4, using farm manure, can improve soil fertility but may not directly address erosion in a desert region.