Green Revolution: Impacts, limits, and the path ahead

1 Green revolution : Impacts, limits , and the path aheadPrabhu L. Pingali1 Bill & Melinda Gates Foundation, Agricultural Development, Seattle, WA 98102 Edited by William C. Clark, Harvard University, Cambridge, MA, and approved June 25, 2012 (received for review April 2, 2012)A detailed retrospective of the Green revolution , its achievement and limits in terms of agricultural productivity improvement, and itsbroader impact at social, environmental, and economic levels is provided. Lessons learned and the strategic insights are reviewed as theworld is preparing a redux version of the Green revolution with more integrative environmental and social impact combined withagricultural and economic development.

2 Core policy directions for Green revolution that enhance the spread and sustainable adoptionof productivity enhancing technologies are public goods|nutrition|poverty|technology|agric ultural developmentThe developing world witnessedan extraordinary period of foodcrop productivity growth over thepast 50 y, despite increasing landscarcity and rising land values. Althoughpopulations had more than doubled, theproduction of cereal crops tripled duringthis period, with only a 30% increase inland area cultivated (1). Dire predictionsof a Malthusian famine were belied, andmuch of the developing world was able toovercome its chronic food deficits. Sub-Saharan Africa continues to be the ex-ception to the global of the success was caused by thecombination of high rates of investmentin crop research, infrastructure, and mar-ket development and appropriate policysupport that took place during thefirstGreen revolution (GR).

3 I distinguish thefirst GR period as 1966 1985 and the post-GR period as the next two decades. Largepublic investment in crop genetic im-provement built on the scientific advancesalready made in the developed world forthe major staple crops wheat, rice, andmaize and adapted those advances to theconditions of developing countries (2).The GR strategy for food crop pro-ductivity growth was explicitly based on thepremise that, given appropriate institu-tional mechanisms, technology spilloversacross political and agroclimatic bound-aries could be captured. However, neitherprivatefirms nor national governments hadsufficient incentive to invest in all of theresearch and development of such inter-national public goods.

4 Privatefirms oper-ating through markets have limited interestin public goods, because they do not havethe capacity to capture much of the benefitthrough proprietary claims; also, becauseof the global, nonrival nature of the re-search products, no single nation has theincentive to invest public resources in thistype of public goods institutionswere needed tofill this gap, and efforts todevelop the necessary institutional capacity,particularly in plant breeding, were a cen-tral part of the GR strategy. Based on theearly successes with wheat at the Inter-national Maize and Wheat ImprovementCentre (CIMMYT) in Mexico and rice atthe International Rice Research Institute(IRRI) in the Philippines, the ConsultativeGroup on International Agricultural Re-search (CGIAR) was established specif-ically to generate technological spilloversfor countries that underinvest in agricul-tural research, because they are unable tocapture all of the benefits of those invest-ments (3).

5 After CGIAR-generatedknowledge, invention, and products (such asbreeding lines) were made publicly avail-able, national public and private sectorsresponded with investments for technologyadaptation, dissemination, and that success, in the post-GRperiod, investment in agriculture droppedoff dramatically into the mid-2000s (4).However, the need for continued invest-ments in agricultural innovation and pro-ductivity growth is as important today as itwas in the early years of the GR. Low in-come countries and lagging regions ofemerging economies continue to rely onagricultural productivity as an engineof growth and hunger reduction (5 7).However, sustaining productivity gains,enhancing smallholder competitiveness,and adapting to climate change are be-coming increasingly urgent concernsacross all production the mid-2000s and heightened afterthe 2008 food price spikes, there has beenrenewed interest in agricultural investment,and there are calls for the next GR, in-cluding those calls made by the formerSecretary General of the United NationsKofiAnnan and Sir Gordon Conway (3, 8).

6 Simultaneously, there is recognition of thelimitations of thefirst GR and the needfor alternative solutions that correct forthose limitations and unintended conse-quences (5). GR must address theseconcerns both where the GR was successfuland in low income countries and laggingregions, where agricultural productivity isstill low. This paper reviews the evidenceon the diffusion and impact of GR cropgenetic improvements and the limitationsand unintended environmental, social,and institutional consequences of the GRstrategy for productivity growth. Then, Iturn to the current period and the renewedinterest and investment in agricultural de-velopment, and I give the technology andinstitutional priorities for a GR GR: Diffusion and impact of CropGenetic ImprovementsPositive impacts on poverty reduction andlower food prices were driven in large partby crop germplasm improvements inCGIAR centers that were then transferredto national agricultural programs foradaptation and dissemination.

7 The pro-ductivity gains from crop germplasm im-provement alone are estimated to haveaveraged per annum for wheat (acrossall regions), for rice, for maize,and and for sorghum andmillets, respectively (9). Adoption rates ofmodern varieties in developing countriesincreased rapidly, reaching a majority ofcropland (63%) by 1998 (9 15).However, global aggregates mask greatgeographic disparities. In Asian countries(including China), the percentage of areaplanted to modern varieties was 82% by1998, whereas improved varieties coveredonly 27% of total area planted in Africa(16). This difference may be, in part, be-cause of the later introduction of CGIAR research programs focused on Africa aswell as the lag in breeding efforts for theorphan crops crops that did not benefitfrom a backlog of research conducted be-fore the GR period but had improvementthat came during the GR and post-GRperiods, such as cassava, sorghum, andmillets which are of greater relative im-portance to the African poor (10).

8 ForAuthor contributions: wrote the of interest statement: All the reviewers suggestedare grantees of the Gates Foundation. It is hard tofindreviewers who are not grantees. None of the reviewershave any connections with the work in the article is a PNAS Direct : 12308|PNAS|July 31, 2012|vol. 109|no. by guest on January 27, 2022 instance, thefirst CIMMYT maize pro-gram focused on Africa only began in thelate 1980s. Although the InternationalInstitute for Tropical Agriculture researchfor cassava started in 1967, its impact wasfelt only since the 1980s (10). Althoughit lagged behind in the GR period, Africahas witnessed positive growth in the post-GR period.

9 Adoption of improved varie-ties across sub-Saharan Africa reached70% for wheat, 45% for maize, 26% forrice, 19% for cassava, and 15% for sor-ghum by 2005 (17). impact on Productivity and Food increase in agricultural outputresulting from the GR came from an im-pressive increase in yields per 1960 and 2000, yields for all de-veloping countries rose 208% for wheat,109% for rice, 157% for maize, 78% forpotatoes, and 36% for cassava (18). De-veloping countries in southeast Asia andIndia were thefirst countries to show theimpact of the GR varieties on rice yields,with China and other Asian regions expe-riencing stronger yield growth in the sub-sequent decades (19).

10 Similar yield trendswere observed for wheat and maize in Asia(20). Analysis of agricultural total factorproductivity (TFP)finds similar trends tothe partial productivity trends captured byyield per hectare [TFP is defined as theratio of total output to total inputs in aproduction process (20)] (21). For theperiod 1970 1989, change in global TFPfor agriculture was , which nearlydoubled to from 1990 to 2006 (21).Crop genetic improvement focusedmostly on producing high-yielding varieties(HYVs), but the decrease in time to ma-turity was also an important improvementfor many crops, allowing for an increasein cropping intensity. The rapid spreadof the rice wheat system in the Indo-Gangetic plains (from Pakistan to Ban-gladesh) can be attributed to the shorten-ing of the crop growing period (22).