The ancient and widespread use of tree and bush fallows to restore soil productivity following several years of cropping has resulted in research aimed at identifying, planting and managing trees for soil improvement. The goal is either to reduce the traditional fallow periods (normally between four and 25 years), or to eliminate the fallow period by introducing systems in which 'soil-improving' trees are managed together with crops or pasture species (agroforestry). Trees commonly used by farmers for soil improvement include Acioa barteri, calliandra calothyrsus, Cassia reticulata, Erythrina poeppigiana, Faidherbia albida, Gliricidia sepium, Inga edulis, Leucaena leucocephala, Prosopis cineraria, and Sesbania sesban. Although many of these species are largely undomesticated, several are currently the focus of genetic improvement programmes. The possibility exists that in such programmes, selections could be made for tree characteristics to significantly improve soils. A synthesis of the research data from work on acid and high base status soils in the humid, subhumid, and semi-arid regions of Central and Latin America, Africa and Asia is used to evaluate critically 'tree/soil improvement' hypotheses related to nutrient cycling, organic matter additions, and nitrogen fixation. These hypotheses are discussed in the context of developing domestication strategies for multipurpose species, taking account of the influence of the species on the soil environment.
Publication year
1994
Authors
Fernandes, E.C.M.; Garrity, D.P.; Szott L T; Palm C A
Language
English
Keywords
agroforestry, biological competition, cassia, cycling, domestication, erythrina poeppigiana, faidherbia albida
