| 1er. Resumen: | The gap between world food supply and demand becomes wider with time. Unemolyment increases rapidly, and with the high rate of inflation, net family income has been largely reduced. Through better utilization of time and spacae, multiple cropping holds promise in relieving the world of these problems. Despite its long histokry and growing importance, relatively few studies exisst on the proper management of multiple cropping patterns. The purpose of this sstudy was to evaluate the agronoomic adaptation, management and economic profitability of twelve sequential cropping systems to a subtropical environment and to determine the nitrogen (N) removal by each system. The study was conducted in Gainesville, Florida, baetween the falls of 1976 and 1978 on an Arredondo fine sand (member of the loamy, siliceous, hyppperthermic family of the Grossarenic Pauleudults). The twelve systems consisted of wheat (Triticum aestivum L.) as the winter crop, succeeded by summer crops of millet (Pennisetum americanum (L.) K. Schum), sorghum (Sorghum bicolor (L.) Moench), x sudangrass (Sorghum sudanense (Piper) Stapf), forage sorghum, and their ratoons, corn (Zea mays L.) for forage an grain, and watermelon (Citrullus lanatus (Thumbs) Mansf). Both of the corn crops and the watermelos crop were followed by millet, sorghum x sudangrass, and forage sorghum as a second summer crop. Besides cropping systems, five row spacings (25, 50, 75, 100 and 125 cm) werw used to evaluate yield response and N removal of millet, sorghum x sudangrass, and forage sorghum in 1977. This study shows that high yielding multiple cropping systems with high cash returns are adapted to subtropical environments. It also demonstates that most systems evaluated were efficiently removing N from the soil. |