Here is a natural way to get nitrogen into the soil using a very resilient legume: clover. Especially when the plant is being returned to the soil. The white clover shown here stays short for the most part. I’ve seen it grow up to 6 inches. Clover is edible (at your own risk be sure the land is clean and you have the right plant), gives nectar to bees, food for rabbits, and prevents soil erosion. It was and is used for healthy pastures as well.