My friend, forget about swales on those slopes. Many people have died in landslides on slopes like that please be very very careful what advice you give others. The key to working those steep heavy clay slopes is contour hedgerows. With inga or other early and mid succession trees to get started. They will stop erosion, give you mulch for the corn to cycle nutrients and over time if you also plant vetiver or lemongrass start to form terraces. In the tropics in swales are very delicate because in large rainstorms we can get 8 or 10 inches of rain and it will either wash out the earthworks or cause a landslide that can take lives. You can plant out contour lines at 5 or 6 m and have plenty of room for annual crops and along the tree lines plant out banana and other fruit trees that will add income and food security. Again please be very very careful when you give advice to someone else especially if you have not done it first
