Resumen

ESPANA¹, Mingrelia; CABRERA-BISBAL², Evelin  y  LOPEZ³, Marisol. Study of nitrogen fixation by tropical legumes in acid soil from venezuelan savannas using 15n. INCI [online]. 2006, vol.31, n.3, pp.197-201. ISSN 0378-1844.

In Venezuela, around 70% of cultivable land presents limitations by acid pH and low availability of P and N in the soil. Sustainable N-replenishment strategies, particularly for low-to medium-input systems on acid soil of savannas, could make use of biological N2- fixation. The object of this study was to estimate the biological nitrogen fixation (BNF) potential of various tropical legumes grown in acid soil from Venezuelan savannahs by 15N-techniques. The results suggest that the Cajanus cajan is a legume with high capacity for N2 fixation (79% N derived from the atmosphere), providing a positive N balance into the fallow system. The estimation of BNF in all legumes varied with the non-N2 fixing reference crops used, confirming that the use of an inadequate reference crop can result in erroneous estimates of BNF especially when the level of N2 fixation is low. The legume Indigosphera lespediciodes shows potential for use as an alternative green manure because of high total N accumulation and N derived from the atmosphere (62-71%). The results demonstrate that in acid soil it is possible to promote sustainability of agrosystems through the use of conservationist management practices

Palabras clave : Acid Soil; Indigosphera lespediciodes,; N Fixation; 15N-technique; Pigeon pea.