Range grass areas including stands of subclover produced forage yields equal to those from nitrogen-fertilized annual grasslands in a moisture-deficient year in northern California, and more forage was produced in a moisture-adequate year, according to this study. Stands of subclover and grass produced forage yields equal to those from California annual-type grasslands fertilized with 45 to 90 kg of nitrogen (N) per hectare (45 kgN/ha = 40 Ib/acre), in a moisturedeficient year (when rains began and ended in March). In a moisture-adequate year (with rains commencing in early October and ending in May), subclover-grass stands produced more forage than did resident grasslands fertilized with 179 kg N per ha. Nitrogen fertilization was found to contribute most to forage production during the winter period. Second- and third-year stands of subclover also showed production increases early in the season, but made the greatest gains in April and May.