Agronomy for Sustainable Development

, Volume 31, Issue 1, pp 139–154

Biological nitrogen fixation and socioeconomic factors for legume production in sub-Saharan Africa: a review

  • Jonas. N. Chianu
  • E. M. Nkonya
  • F. S. Mairura
  • Justina. N. Chianu
  • F. K. Akinnifesi
Review Article

DOI: 10.1051/agro/2010004

Cite this article as:
Chianu, J.N., Nkonya, E.M., Mairura, F.S. et al. Agronomy Sust. Developm. (2011) 31: 139. doi:10.1051/agro/2010004

Abstract

Low crop productivity is a general problem facing most farming systems in sub-Saharan Africa (SSA). These low yields are pronounced in grain legumes and are often associated with declining soil fertility and reduced N2-fixation due to biological and environmental factors. Unfortunately, the majority of African small farmers are now unable to afford the high mineral fertilizer prices. More than 75% of the fertilizers used in Africa are imported, putting pressure on foreign exchange. Low cost and sustainable technical solutions compatible with the socioeconomic conditions of small farmers are needed to solve soil fertility problems. Biological nitrogen fixation (BNF), a key source of N for farmers using little or no fertilizer, constitutes one of the potential solutions and plays a key role in sustainable grain legumes (e.g., soybean) production. Given the high cost of fertilizer in Africa and the limited market infrastructure for farm inputs, current research and extension efforts have been directed to integrated nutrient management, in which legumes play a crucial role. Inoculation with compatible and appropriate rhizobia may be necessary where a low population of native rhizobial strains predominates and is one of the solutions which grain legume farmers can use to optimize yields. It is critical for sustained yield in farmlands deficient in native rhizobia and where N supply limits production. Research on use of Rhizobium inoculants for production of grain legumes showed it is a cheaper and usually more effective agronomic practice for ensuring adequate N nutrition of legumes, compared with the application of N fertilizer. Here, we review past and ongoing interventions in Rhizobium inoculation (with special reference to soybean) in the farming systems of SSA with a view to understanding the best way to effectively advise on future investments to enhance production and adoption of BNF and inoculant technologies in SSA. The major findings are: (1) complete absence of or very weak institutions, policy and budgetary support for biotechnology research and lack of its integration into wider agricultural and overall development objectives in SSA, (2) limited knowledge of inoculation responses of both promiscuous and specifically nodulating soybean varieties as well as the other factors that inhibit BNF, hence a weak basis for decision-making on biotechnology issues in SSA, (3) limited capacity and lack of sustainable investment, (4) poorly developed marketing channels and infrastructure, and limited involvement of the private sector in the distribution of inoculants, and (5) limited farmer awareness about and access to (much more than price) inoculants. The lessons learned include the need: (1) to increase investment in Rhizobium inoculation technology development, and strengthen policy and institutional support, (2) for public private partnership in the development, deployment and dissemination of BNF technologies, (3) to develop effective BNF dissemination strategies (including participatory approach) to reach farmers, (4) for greater emphasis on capacity building along the BNF value chain, and (5) for partnership between universities in SSA and those in the North on BNF research.

Keywords

low soil fertility N2 fixation inoculants soybean adoption drivers sub-Saharan Africa 

List of abbreviations

ASK

Agricultural Society of Kenya

BCR

Benefit Cost Ratio

BNF

Biological Nitrogen Fixation

CAN

Calcium Ammonium Nitrate

CIAT

Centro Internacional Agricultura de Tropical

DAP

Di-Ammonium Phosphate

DR-Congo

Democratic Republic of Congo

FAO

Food and Agriculture Organization of the United Nation

FYM

Farmyard manure

IAEA

International Atomic Energy Agency

IITA

International Institute of Tropical Agriculture

IFDC

International Fertilizer Development Center

INM

Integrated Nutrient Management

ISAR

Institut des Sciences Agronomique du Rwanda

KARI

Kenya Agricultural Research Institute

KIOF

Kenya Institute of Organic Farming

KShs

Kenya Shillings

LSD

Least Significant Difference

MIRCEN

Microbiological Resources Center

MRR

Marginal Rate of Returns

N

Nitrogen

NGO

Non-governmental organization

NPK

Nitrogen Phosphorus Potassium

OMMN

Organic Matter Management Network

P

Phosphorus

R&D

Research and Development

SPRL

Soil Productivity Research Laboratory

SSA

Sub-Saharan Africa

SUA

Sokoine University of Agriculture

TGx

Tropical Glycine crosses

UNEP

United Nations Environment Program

UNESCO

nited Nations Educational, Scientific and Cultural Organization

USAID

nited States Agency for International Development

USDA

nited States Department of Agriculture

US$

nited States of America Dollar

Copyright information

© INRA and Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Jonas. N. Chianu
    • 1
  • E. M. Nkonya
    • 2
  • F. S. Mairura
    • 1
  • Justina. N. Chianu
    • 1
  • F. K. Akinnifesi
    • 3
  1. 1.TSBF-CIAT, c/o World Agroforestry Centre (ICRAF)NairobiKenya
  2. 2.International Food Policy Research Institute (IFPRI)Washington DCUSA
  3. 3.World Agroforestry Centre (ICRAF)Chitedze, LilongweMalawi

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