Changing C and N Levels of miombo woodland litter.

Abstract

Litterfall was collected fortnightly from four-25 m2 cleared miombo woodland plots for five years. The litter was fractionated and compared for quantity, monthly distribution and concentrations of total C and N. Annual litterfall, starting at the beginning of the dry season (May) to the end of the rainy season (April), ranged from 283.3 to 507.8 g m-2 year-1. A peak of litterfall occurred in all the five years during the May to September period. Although the proportion varied from year to year, leaflets litter were always the largest component of the annual litter fall ranging from about 34-44% of total litterfall. This represented an annual nutrient pool of between 546-1043 kg C ha-1 and between 17-31 kg N ha-1. Although C contents in each litter fraction did not differ significantly during the 12-month sampling period, total N concentrations differed greatly during the same periods (p < 0.05). While N concentrations showed considerable declines from July to October in most of the litter fractions, seed litter showed a significant N increase. C:N ratios were lowest in litter collected during the mid-rainy season (December to March), 22 and highest in September, 43 implying that mid-rainy season miombo litter may have the potential of releasing N to growing plants. These results show that there may be need for more detailed studies relating organic materials used in soil fertility improvements to synchronize with plant demand.


Transactions of the Zimbabwe Scientific Association Volume 72 (Supplement) 1998, pp. 48-54