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Soil Organisms Aid Crop Productivity by Increasing Yields
18/ 05/ 2010

Soil Organisms Aid Crop Productivity by Increasing YieldsNairobi, Kenya (17 May 2010)-Soil-living bacteria and fungi can be used to boost crop yields by more than 50 per cent without the use of fertilizers, an international research project has found.

In combination with fertilizers, yields of key crops such as beans, can more than double, the scientists from seven countries discovered.

The findings, the result of an international effort to unravel the mysteries of so-called 'below ground biodiversity', are likely to have important implications for food security and farmers livelihoods and incomes.

The amount of fertilizer needed to boost yields is far less than using inorganic fertilizer on its own. Other important findings are that some of the micro-organisms assist in fighting crop diseases which in turn can reduce the need for pesticides.

For farmers switching to organic agriculture-whose produce commands higher premiums on world markets-this could prove especially valuable.

The findings were announced today at the opening of a week-long conference at the World Agroforestry Centre. The conference, bringing together some 70 experts, will outline how the soil organisms work, where they live and how they are extracted from the soil and packaged to work in the farmers' fields and in other ecosystems.

The research project, entitled the Conservation and Sustainable Management of Below Ground Biodiversity (CSM-BGBD), has involved scientists from Brazil, Cote d'Ivoire, India, Indonesia, Kenya, Mexico and Uganda.

The eight-year project has been coordinated by the Tropical Soil Biology and Fertility Institute of CIAT (TSBF-CIAT) with co-financing from the Global Environmental Facility (GEF), and implementation support from the United Nations Environment Program (UNEP).

Some Key Findings
Studies in Kenya indicate that inoculation with Rhizobium bactreia increased soybean yields by 40%, 60% and 54% in Homabay, Kabete and Mtwapa, respectively, without the use of fertilizers.

However, when the organisms like Trichoderma are used in combination with fertilizers like Mavuno, which have micro-nutrients, bean yields more than doubled.

These findings were reported in a paper published in an internal journal in December 2009, led by Dr. Sheila Okoth of University of Nairobi.

The findings of this project also show significant economic returns.

Using Rhizobia as bio-fertilizers, for example, in combination with Triple Super Phosphates (TSP) fertilizers can produce a benefit to cost ratio of 2.3 that translates to a net benefit of US$253 after cost deductions for one hectare of land.

Using the fertilizer on its own has a cost benefit ratio of 1.9 with a net benefit of US$170 and deploying Rhizobia alone gives a similar cost-benefit ratio with a net benefit of US$143.

Benefits arise in terms of a lowering of costs to farmers with the soil organisms assisting to improve the efficient use of nutrients and improved utilization of water.

A paper published by CIAT scientist - led by Dr. Jonas Chianu - also indicates that the financial value of the nitrogen fixing attribute of soybean in sub-Saharan Africa annually amounts to about US$200 million across 19 countries.

With the fertilizer price of US$795 per ton (as of June 2008), this would amount to US$375 million.

Notes to Editors
Details of the Conservation and Sustainable Management of Below-Ground Biodiversity (CSM-BGBD) project can be found at

This week's conference at the WorldAgroforestry Centre provides a platform in which scientists provide recommendations on what needs to be done to implement the use of these micro-organisms and how it can be done.

There will be policy entry points prepared, and panel discussion on policy matters that should translate the findings of the project to meaningful issues for attention.

For background information, images, and maps, please visit the online press room at:

For more information and interview requests, contact

Dr. Peter Okoth, Project Information Manager, +254 722 768537 or at

Mr. Brian Etyan, Project Information Assistant, +254 723 585 061 or at

Dr. Jeroen Huising, Global Project Coordinator, +254 714 636 606 or at

Further Resources
Below Ground Biodiversity project website