The document summarizes research on the effect of integrated soil fertility management techniques on soybean grain yield in Ghana. It found that: 1) The early-maturing soybean entry "Anidaso" produced significantly higher yields than other varieties tested, while the late-maturing variety "Sonda" produced significantly lower yields. 2) Applying nitrogen, phosphorus and potassium fertilizers together with rhizobium inoculation resulted in significantly higher grain yields than using inoculation alone for both early- and late-maturing soybean entries. 3) The research concludes that soybean production in Ghana can be intensified by planting inoculated seeds of high-yielding varieties like "Anidaso",

1. Soybean Grain Yield Responses to Integrated Soil Fertility Management
Asamoah Larbi1, Saaka Buah2, Nicholas Denwar2 , Abdul Rahman Nurudeen1, and Irmgard Hoeschle-Zeledon1
1International Institute of Tropical Agriculture, Africa RISING Project, Ibadan, Nigeria
2Savana Agricultural Research Institute, Nyankpala, Tamale, Ghana
Corresponding author email: a.larbi@cgiar.org
The Africa Research In Sustainable Intensification for the Next Generation (Africa RISING) program comprises three research-for-
development projects supported by the United States Agency for International Development as part of the U.S. government’s Feed the
Future initiative.
Through action research and development partnerships, Africa RISING will create opportunities for smallholder farm households to move out
of hunger and poverty through sustainably intensified farming systems that improve food, nutrition, and income security, particularly for
women and children, and conserve or enhance the natural resource base.
The three projects are led by the International Institute of Tropical Agriculture (in West Africa and East and Southern Africa) and the
International Livestock Research Institute (in the Ethiopian Highlands). The International Food Policy Research Institute leads an
associated project on monitoring, evaluation and impact assessment.
www.africa-rising.net
Introduction
Soybean (Glycine max) is an important cash and oil
crop in Ghana used in cereal-legume rotations to fix
atmospheric nitrogen to improve soil fertility and as
a trap-crop against Stirga hermonthica, a parasitic
weed that causes severe yield losses in cereal
crops. Grain yields are low on farmers’ fields partly
due low availability of soil nutrients, especially
nitrogen (N), phosphorus (P) and potassium (K) and
inappropriate management practices, e.g.,
unimproved varieties, no fertilizer and Rhizobium
inoculant application
The Africa Research in Sustainable Intensification
(Africa RISING) project is testing and demonstrating
several agricultural technologies to intensify and
sustain crop yields in small-scale crop-livestock
farming systems in Northern Ghana. Results of two
multi-locational trials to test and demonstrate the
effect of using fertilizer N, P and K and Rhizobium
inoculants on grain yield of early-maturing and late-
maturing soybean entries are presented.
Procedures
Five integrated soil fertility management (ISM)
options on grain yields of early-maturing (85-90
days) and late-maturing (100-110 days) soybean
entries were evaluated in Trials 1 and 2 respectively
in 2012 and 2013. A split-plot design with entries as
main-plots and ISFM as sub-plots was used in both
trials.
In 2012, Trial 1 was conducted at Bamahu and Trial
2 at Nyankpala, Yendi and Wa. In 2013, Trial 1 was
conducted at Bamahu and Wa, and Trial 2 at
Nyankpala, Yendi, Bamahu and Wa.
The N, P and K rates were 25, 60 and 30 kg/ha as
(urea), P2O5 (triple superphosphate) and K2O
(muriate of potash) respectively. The soybean
entries were chosen based on their performance in
earlier on-station and on-farm trials. Inter and intra-
row spacing were 60 x 5 cm for the early-maturing
and 75 x 5 cm for the late. Details of the soybean
entries and ISM treatments are presented in Figures
1-4.
Days to 50% flowering, plant height, nodule
numbers and nodule weight per plant and grain
yield were recorded. Means of grain yield are
presented across year and site.
Figure 1: Grain yield of early-maturing soybean entries, average of 3 sites in 2012 and 2013
Grain yield of Anidaso was higher (P<0.05) than the other early maturing entries (Fig. 1),
whilst that of Sonda was lower (P<0.05) the rest of the late maturing varieties (Fig. 2).
Applying N, P and K fertilizer and Rhizobium inoculation produced more (P<0.05) grain
than inoculation alone (Figs. 3 and 4).
Conclusion
Soybean production can be intensified by planting inoculated seeds of Anidaso,
Jenguma, Afayak and the unreleased entries with P and K fertilizer.
Acknowledgement
Africa RISING is supported by USAID as part the Feed the Future Initiative of the US
Government. The authors are grateful for the financial support.
Results summary
1000 2000 3000 4000
Songda
Afayak
Jenguma
TGX-1904-6F
TGX-1448-2E
Grain yield (kg/ha)
0 500 1000 1500 2000 2500
Suong-Pungu
TGX-1805-8F
Anidaso
Grain yield (kg/ha)
Figure 2: Grain yield of late-maturing soybean entries, average of 7 sites in 2012 and 2013
1400 1500 1600 1700 1800
No fertilizer (Control)
Rhizobium inoculation ('R)
60kg P/ha + 30kg K/ha
25kg N/ha + 60kg P/ha + 30 kg K/ha
R + 60kg P/ha + 30kg K/ha
Grain yield (kg/ha)
Figure 3: Grain yield of early-maturing soybean entries, average of 3 sites in 2012 and 2013
1000 2000 3000 4000
No fertilizer (Control)
Rhizobium inoculation ('R)
25kg N/ha + 60kg P/ha + 30 kg K/ha
R + 60kg P/ha + 30kg K/ha
60kg P/ha + 30kg K/ha
Grain yield (kg/ha)
Figure 4: Grain yield of late-maturing soybean entries, average of 7 sites in 2012 and 2013