AMELIORATION OF A DEGRADED OXIC PALEUSTALF BY LEGUMINOUS AND NATURAL FALLOWS

The restorative ability of herbaceous (Psophocarpus palustris, Puerari a phaseoloides) and woody (Leucaena leucocephala, Senna siamea, Acacia leptocarpa, Acacia auriculiformis) legume species and of natural regr ow-th was studied on an eroded and compacted Oxic Paleustalf in southw estern Nigeria. Compared to the control treatment that was continuousl y cropped for 15 years, four years of fallowing significantly improved test crop yields. However fallowing with the above species did not su bstantially improve soil properties, particularly soil bulk density. A longer fallow period may be needed to amend soil physical conditions of this degraded Alfisol. Soil chemical properties were greatly improv ed following land clearing and plant biomass burning in 1993. However, the residual effect of burning on soil fertility was insignificant in the second cropping year. Among the fallow species, P palustris and n atural fallow-showed the best residual effect on test crop performance . Despite the high biomass and nutrient yields of S. siamea and A. aur iculiformis, test crop yields on these plots were low due to the borde r effects from the uncleared and fallowed subplots.