NUTRITIONAL EFFECTS OF EUCALYPTUS LITTER ON THE GROWTH OF MAIZE (ZEA-MAYS)

The effects of Eucalyptus leaf litter on the germination, nutrition and growth of maize were studied. Foliar extracts from Eucalyptus leaf litter inhibited maize germination. Germination was good in pots but growth of the first maize crop was reduced by about 68% by application of Eucalyptus leaf litter. Opposite results were obtained in a second maize crop planted in the same soil which showed an increase of 97% in shoot dry weight compared with the untreated control. Retardation of maize growth in the first cycle was inhibited mostly by nutrient immobilisation. Significant correlations were found between total N and P uptake and growth of maize. The concentration of these elements in maize from unmulched soil at the second crop was about twice that in the first crop. Field studies were conducted to compare some soil chemical properties of a field under a Eucalyptus grandis plantation and a woodland dominated by Brachystegia spiciformis (miombo woodland). The soil under Eucalyptus had more organic matter, NH4-N, Ca and P than that collected under miombo woodland. The latter had higher NO3-N, K, Mg and pH. Most of the nutrients were concentrated at a depth of between 0 and 5 cm with an accumulation of soil organic matter, P, Mg and K at a depth of between 40 and 50 cm. Although the growth of maize was much better in soils collected between 0 and 10 cm in the miombo woodland, no significant correlation was obtained between various nutrient elements measured at different depths and growth of maize with the exception of the higher NO3-N supply.