Perennial crops, guinea grass and alfalfa, and annual crops, wheat and cotton, were grown in the reclaimed Hula Valley swamp. The aim was to find ways to preserve the peat soil from aerobic oxidation, wind and water erosion; to minimize nitrate accumulation, which causes pollution of the waters draining into the Kinneret Lake (Sea of Galilee); and to select high yielding crops that both fulfilled these needs and ensured a good income for the farmers. Our results showed that high dry matter yields of guinea grass and alfalfa could be obtained. A significant decrease in peat soil erosion and nitrate accumulation was also recorded under these perennial crops, so growing them has both economic and ecological advantages. © 1987, Cambridge University Press. All rights reserved.