NITROGEN-USE EFFICIENCY FOR GROWTH IN A CULTIVATED AFRICAN GRASS AND A NATIVE SOUTH-AMERICAN PASTURE GRASS

A study of a widely cultivated African grass species, Andropogon gayanus, and an occasionally cultivated native South American species, Paspalum plicatulum, was undertaken to compare their growth rates and N use efficiency when grown in nutritionally poor fertilized savanna soils of Cojedes State, Venezuela. Production potential of A. gayanus was larger and more limited by P than that of P. plicatulum. The African grass is capable of extracting larger quantities of N from the unfertilized savanna soil than the native grass, a capability greatly enhanced by addition of P + K. Neither species responded to fertilization with N and K alone. Differences in growth potential are based on greater nitrogen use efficiency and lower shoot/root ratios in A. gayanus. -from Authors