Nitrogen-Use Efficiency for Growth in a Cultivated African Grass and a Native South American Pasture Grass

Abstract

Frequency and density of introduced African efficiency when grown in nutritionally poor savanna soils grass species in disturbed neotropical ecosystems reveal of Cojedes State in central Venezuela, and fertilized with their adaptability and competitive capacity compared to the intermediate levels of nitrogen + potassium, phosphorus native savanna grass species. A nutritional hypothesis has + potassium, and a combination of nitrogen been advanced to explain the success of these species. De- + phosphorus + potassium. Production potential of A. forested areas provide periods of short duration of high gayanus Kunth was larger and more limited by P than that nutrient availability, while in savannas protected against of Paspalum plicatulum. The African grass is capable of fire a marked increase of nutrient and organic matter extracting larger quantities of N from the unfertilized content in the upper soil layers occurs. There is no direct savanna soil than the native grass, and this capability was evidence indicating that the production potential of intro- greatly enhanced by the addition of P + K. Both species did duced African grasses is lower than that of native grasses not respond to the fertilization with N and K alone. Differ- when they are grown in soils of low fertility. A study of a ences in growth potential are based on greater nitrogen use widely cultivated African grass species, Andropogon efficiency and lower shoot/root ratios in A. gayanus. gayanus Kunth, and an occasionally cultivated native South