Manlay Raphaël J., Masse Dominique, Chevallier Tiphaine, Russell-Smith A., Friot D., Feller Christian. (2004). Post-fallow decomposition of woody roots in the West African savanna. Plant and Soil, 260, 123-136. ISSN 0032-079X.
Titre du document
Post-fallow decomposition of woody roots in the West African savanna
Manlay Raphaël J., Masse Dominique, Chevallier Tiphaine, Russell-Smith A., Friot D., Feller Christian
Source
Plant and Soil, 2004,
260, 123-136 ISSN 0032-079X
Fallowing is a common practice for the management of soil fertility in low-input cropping systems of the West-African savanna, but has been threatened by the growing need for land in the sub-region for the past few decades. Proposals for alternatives to traditional fallowing
must rely on a proper understanding of the soil biochemical dynamics occurring after fallow conversion to cropping. Two mesh-bag experiments were thus conducted in two sites (dry and sub-humid tropical climates) in Senegal to assess the role of site-related factors
(climate, macrofaunal activity) and root-related factors (tree species, root diameter) on the decomposition of tree roots after clearing of fallow vegetation as measured from mass loss. Root decomposition was fastest - and even faster than predicted from a global model
- in the wettest site (first order disappearance rate: 1.00 y-1 and 1.46-1.49 y-1 under dry and sub-humid conditions, respectively). Macrofauna accounted for half of root mass loss in the sub-humid site, with biomass removal occurring even during the dry season. Fastest disappearance
for roots with null sign<5 mm occurred for Dichrostachys cinerea, and Combretum glutinosum. The influence of root chemical composition on decomposition patterns among tree species and root diameter classes was not clear, with effects of cell wall composition and nutrient content changing
throughout the incubation period. Fast disappearance of dead roots suggests that cropping practices that allow conservation of live stumps, such as no-tillage and direct sowing, be promoted wherever possible to ensure soil conservation. It also suggests the possible management of tree
species composition and, to a much lesser extent, of macrofauna during the fallow period to control root decomposition patterns and related nutrient transfers to crop biomass after fallow conversion.
Plan de classement
Macrofaune [074FAUSOL03]
Descripteurs
JACHERE ; RACINE ; DECOMPOSITION ; SAVANE ; FACTEUR CLIMATIQUE ; FAUNE DU SOL ; MACROFAUNE ; ACTIVITE BIOLOGIQUE ; ARBRE ; ESPECE ; FERTILITE DU SOL ; CHIMIE DU SOL
