A two-year field experiment was made of growing Rhodes grass and alfalfa on peat soil of the Hula Valley, where high nitrate accumulation occurs under row crops or plantless soil and leads to the danger of contamination of Lake Kinneret. The aime of the investigation was to use these perennial high-nitrogen-consumer crops to prevent the nitrate accumulation in the peat soil. The results showed a drastic decrease in soil N-NO3 under both species in two irrigation systems obtaining high dry matter yields with high plant nitrogen content without the use of any nitrogen fertilizer. © 1978 Martinus Nijhoff.