Research Article: Rates of return to sorghum and millet research investments: A meta-analysis

Date Published: July 7, 2017

Publisher: Public Library of Science

Author(s): Yacob A. Zereyesus, Timothy J. Dalton, Sanjay B. Jadhao.


Sorghum and millet grow in some of the most heterogeneous and austere agroecologies around the world. These crops are amongst the top five cereal sources of food and feed. Yet, few studies document the impact of sorghum and millet genetic enhancement. The Internal Rate of Return (ROR) is one of the most popular metrics used to measure the economic return on investment on agricultural research and development (R&D). This study conducted a meta-analysis of 59 sorghum and millet ROR estimates obtained from 25 sources published between 1958 and 2015. The average rate of return to sorghum and millet R&D investment is between 54–76 percent per year. All studies computed social rather than private RORs because the technologies were developed using public funds originating from host country National Agricultural Research Systems (NARS) and international organizations such as the INTSORMIL CRSP, ICRISAT and others. Nearly three quarter of the studies focused only on sorghum (72 percent) and around one tenth of the studies (8 percent) on millet. Regression models analyzed the determinants of variation in the reported RORs. Results show that ex-ante type and self-evaluated type of analyses are positively and significantly associated with the ROR estimates. Compared to estimates conducted by a university, results from international institutions and other mixed organizations provided significantly smaller estimates. Estimates conducted at national level also are significantly lower than those conducted at sub-national levels. The ROR is higher for studies conducted in the United States and for those conducted more recently. The study also reconstructed modified internal rate of return (MIRR) for a sub-sample of the reported RORs following recent methods from the literature. These results show that the MIRR estimates are significantly smaller than the reported ROR estimates. Both results indicate that investment in sorghum and millet research generates high social rates of return.

Partial Text

Sorghum and millet are some of the world’s most important cereal crops especially in semi-arid areas of the Americas, sub-Saharan Africa and Asia. These two crops are important food and feed crops, especially in environments with heat and water stresses that characterize the semi-arid and arid drylands that are the home to 1.4 billion of the world’s population. A sizable portion of the world sorghum and millet production comes from sub-Saharan Africa and Asia [1]. For example, in 2014, of the top 20 sorghum and millet producing countries, 70 percent for sorghum and 85 percent for millet came from Africa and Asia. Three out of the top five highest sorghum-producing countries and the five most important highest millet-producing countries are from Sub-Saharan Africa and Asia [1]. Other major countries involved in sorghum and millet production and trade include the United States, Mexico, Argentina, Brazil, and Australia.

Historical returns on sorghum and millet R &D investments have been socially profitable. On a global coverage, the average ROR to sorghum and millet agricultural R&D investments is in the range of 58–81 percent per year. A number of notable results are observed from the review. The majority of the economic impact assessment studies are ex-post type analyses conducted in Sub-Saharan African countries. Both variables were negatively related to the rate of return. Self-evaluated impact assessment studies had higher RORs but this was counteracted if the self-evaluation was conducted by a researcher from an international institution or a team of researchers from universities collaborating with an international institution. Published studies presented lower rates of returns than unpublished manuscripts. Studies assuming a proportional supply shift produced results that were lower than others.




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