number of species has been thoroughly tested. The
following N-fixing leguminous species have been
shown to be suitable for use in tropical alley cropping:
1. Gliricidia sepium and Leucaena leucocephala,
for use on high base status soils in the lowland
humid zone;
2. Cajanus cajan, Calliandra calothyrsus, Erythrina
poeppigiana and Flemingia macrophylla for use
at higher altitudes;
3. Flemingia macrophylla and Dactyladenia barteri
for use on acid soils in the humid zone.
Further research is needed to identify other N-fixing
MPTS for use on acid soils.
Traditional alley cropping systems have been practised for some time in the Ethiopian highlands,
on acid soils in southeastern Nigeria, and on degraded
and sloping lands in southern Philippines and
eastern Indonesia. These systems were used by traditional
farmers to sustain low yield crop production
with no external chemical input or as a source of
browse and other auxiliary products.
The alley cropping technique has been tested and
used for the production of various food and forage
crops. In the past two decades, a large number of
alley cropping trials have been carried out in various
ecozones of the humid and subhumid tropics. Although
most of these trials dealt with the adaptibility
of the system, they have also yielded information on
the potential and limitations of this technique