Contour planting in the Forest Garden:

Contour planting is helpful for mitigating soil erosion and runoff on hilly or sloped land. On flat land, properly managing the landscape and incorporating agroforestry techniques - such as alley cropping, and windbreaks - can lead to more stable and fertile soil. On sloped land, during rains, runoff is often unable to percolate into the soil and will flow down the hillside, carrying away topsoil and valuable nutrients. Recommended on slopes with an incline greater than 5%, planting contours allows farmers to greatly reduce this challenge.

Farmers begin by locating the highest point in their field and using tool called an A-frame to identify the level lines. It is recommended that a contour row is added every 2 meters of vertical drop. For planting, vetiver is a great example of a species to include.
 
As the plants grow, their roots bind the soil below while the branches help trap soil from runoff above, eventually forming a small ridge or dam. When water reaches this ridge, it slows or stops flowing, depositing soil and allowing the water to percolate into the soil. Over time, the land can level out behind contour plantings, creating terraces.