REGULAR ARTICLE
Meta-analysis of maize yield response to woody
and herbaceous legumes in sub-Saharan Africa
Gudeta Sileshi
&
Festus K. Akinnifesi
&
Oluyede C. Ajayi
&
Frank Place
Received: 7 August 2007 / Accepted: 8 January 2008 / Published online: 18 April 2008
#
Springer Science + Business Media B.V. 2008
Abstract A number of studies have tested the effect of
woody and herbaceous legumes on soil fertility and
maize yields in sub-Saharan Africa. However, their
effects on maize productivity are much debated
because results have been variable. A meta-analysis
was conducted with the aim of evaluating the evidence
in support of yield benefits from woody and herba-
ceous green manure legumes. A total of 94 peer-
reviewed publications from West, East and southern
Africa qualified for inclusion in the analysis. Maize
yield from herbaceous green manure legumes (54
publications), non-coppicing legumes (48 publica-
tions), coppicing woody legumes (10 publications),
natural fallows (29 publications), and fully fertilized
monoculture maize (52 publications) were compared.
Mixed linear modelling using yield differences (D)and
response ratios (RR) indicated that the response to
legumes is positive. The mean yield increase (D)over
unfertilized maize was highest (2.3 t ha
−1
) and least
variable (CV=70%) in fully fertilized maize, while it
was lowest (0.3 t ha
−1
) and most variable (CV=229%)
in natural fallows. The increase in yield over unfertilized
maize was 1.6 t ha
−1
with coppicing woody legumes,
1.3 t ha
−1
with non-coppicing woody legumes and 0.8 t
ha
-1
with herbaceous green manure legumes. Doubling
and tripling of yields relative to the control (RR > 2)
was recorded in coppicing species (67% of the cases),
non-coppicing legumes (45% of the cases), herbaceous
green manure legumes (16% of the cases) and natural
fallows (19% of the cases). However, doubling or
tripling of yields occurred only in low and medium
potential sites. Amending post-fallow plots with 50% of
the recommended fertilizer dose further increased yields
by over 25% indicating that legume rotations may play
an important role in reducing fertilizer requirements.
Except with the natural fallow, the 95% confidence
intervals of D and RR were higher than 1 and 0,
respectively indicating significant and positive response
to treatments. Therefore, it is concluded that the global
maize yield response to legumes is significantly
positive and higher than unfertilized maize and natural
vegetation fallows.
Keywords Cover crops
.
Relay intercropping
.
Response ratio
.
Soil fertility
Plant Soil (2008) 307:1–19
DOI 10.1007/s11104-008-9547-y
Responsible Editor: Elizabeth (Liz) A. Stockdale.
G. Sileshi (*)
:
F. K. Akinnifesi
:
O. C. Ajayi
World Agroforestry Centre (ICRAF),
SADC-ICRAF Agroforestry Programme,
Chitedze Agricultural Research Station,
P.O. Box 30798, Lilongwe, Malawi
e-mail: sgwelde@yahoo.com
F. Place
World Agroforestry Centre (ICRAF),
P.O. Box 30677, Nairobi, Kenya