The Rice Green Revolution in Sub-Saharan Africa: Issues and Opportunities

Abstract

The time is ripe to pursue a Green Revolution in rice in sub-Saharan Africa (SSA) as a means of promoting food security and poverty reduction. This is partly because rice is an up-and-coming crop in this region, and partly because, as will be demonstrated in this volume, we have now accumulated deep knowledge about rice cultivation in SSA. With the aim of generating relevant policy recommendations, this book attempts to show what needs to be done to realize a rice Green Revolution in SSA. It is based on more than ten years of empirical inquiries into rice production by our research team in selected countries, namely Mozambique, Tanzania, Uganda, Kenya, Ghana, and Senegal, along with the newly added case of Cote d’Ivoire. This chapter explains why rice is important, provides a conceptual framework for realizing a rice Green Revolution, and proposes several major hypotheses to be tested in this book.

1 Introduction

While rice production doubled from 2008 to 2018 in sub-Saharan Africa (SSA),¹ rice consumption in this region has increased more rapidly, resulting in the growth of rice imports from Asia. The need for a Rice Green Revolution is now more of a critical issue than ever in SSA because, as will be shown in this chapter, rice is now one of the most important staple crops in the region. Moreover, there is enormous potential for SSA to improve the productivity of lowland rice farming (Balasubramanian et al. 2007).² For these reasons, a rice Green Revolution should be pursued urgently in sub-Saharan Africa to promote food security and poverty reduction.

It must be pointed out at the outset that the Green Revolution is not simply a “seed-fertilizer” revolution, as was pointed out a half-century ago by Johnston and Cownie (1969), but management-intensive (Otsuka and Larson 2013, 2016; Otsuka and Muraoka 2017). That is, the adoption of improved seeds and fertilizer can have significant and sustainable impacts on crop yields and profitability if water, soil, weeds, and rice plants are all effectively managed using improved cultivation practices.³ Thus, we define the Green Revolution as the development and diffusion of high-yielding varieties coupled with the application of improved cultivation practices.

Nevertheless, policymakers and researchers have often assumed that the Green Revolution requires only the use of modern inputs, such as modern varieties (MV) and chemical fertilizers (Gollin et al. 2021; Carter et al. 2021), ignoring the role of improved cultivation practices widely adopted during the Asian rice Green Revolution, such as transplanting (in rows in a timely manner), bunding, and land leveling⁴ (David and Otsuka 1994; Abe and Wakatsuki 2011; Rashid et al. 2013; Ragasa and Chapoto 2017). This misunderstanding explains, at least partly, why SSA has failed to realize the rice Green Revolution before now, even though the revolution began in tropical Asia (i.e., South and Southeast Asia) more than a half-century ago and resulted in dramatic increases in rice and wheat production in the 1970s and 1980s.⁵

This book attempts to show what exactly should be done to realize a rice Green Revolution in SSA based on more than ten years of empirical inquiries into rice production by our research team in selected countries in this region, namely Mozambique, Tanzania, Uganda, Kenya, Ghana, and Senegal, in addition to the new addition of Cote d’Ivoire. Since we are interested in poverty reduction and food security, we focus on smallholder rice farming in SSA (Larson et al. 2014, 2016). Following Schultz (1964), we assume that smallholders are rational and willing to adopt new profitable technologies if they are available. This book, which is based on a number of down-to-earth case studies conducted in several African countries, amply attests to the relevance of the Schultz thesis.

This book is the sequel to the two earlier books on the same subject: K. Otsuka and D. F. Larson eds., 2013, An African Green Revolution: Finding Ways to Boost Productivity on Small Farms; and 2016, In Pursuit of an African Green Revolution: Views from Rice and Maize Farmers’ Fields. The main message of the first book was that rice is likely to be the most promising cereal crop in SSA because of the high transferability of well-established Asian rice Green Revolution technology, whereas the central message of the second book was that rice cultivation training programs are effective in dramatically increasing rice yields in SSA. This third book has broader coverage in terms of topics, study periods, and locations. In fact, this book deals not only with the impact of the rice cultivation training programs in both rainfed and irrigated areas in the short and long term but also with the impacts of mechanization, irrigation, and improved rice milling technology.

This chapter reviews the production trends of major cereal crops in the past in SSA in Sect. 1.2 and examines the prospect of rice production for the future in Sect. 1.3. The conceptual framework is provided in Sect. 1.4, along with the formulation of testable empirical hypotheses. Section 1.5 sets out the structure of the book.

2 Trends in the Past

2.1 Population Pressure and the Increasing Importance of Crop Yield

In SSA, the rural population has continued to grow and cultivable lands have become scarcer over time (Holden and Otsuka 2014). Earlier, farmers converted uncultivated forest and grazing land on the hills into upland crop fields. However, they gradually converted unused marshy land into lowland paddy fields because of the increasingly limited availability of uncultivated land in the hills. However, in general, the land–labor ratio, measured by arable land per capita in the rural population in Fig. 1.1, continued to decline in SSA. While it is true that the land–labor ratio has always been much lower in tropical Asia than in SSA, the level in Asia in 1961 was no different from that of SSA in 2018. This fact indicates that the population pressure on limited land on the eve of the Green Revolution in Asia was as severe as the current population pressure in SSA.

Fig. 1.1

(Source FAOSTAT 2019)

Changes in arable land per capita in rural areas in tropical Asia and SSA

The theory of agricultural intensification proposed by Boserup (1965) and the theory of induced institutional and technological innovations formulated by Hayami and Ruttan (1985) provide a basis for inducing an intensification of the farming system and land-saving technological change. This is likely to result in increasing land productivity as a way of responding to increasing population pressure. Table 1.1 shows annual growth rates of cereal production per capita in rural areas, harvested area per capita in rural areas, and output per harvested area in SSA by decade. Output is measured by a simple sum of the weights of maize, rice, wheat, millet, and sorghum. Since yams and other root crops are also widely grown in SSA, measuring food production only by cereal crops is likely to be inaccurate.

Table 1.1 Annual growth rates of cereal output per capita (rural areas), harvested area per capita (rural areas), and grain output per harvested area in SSA (%)

Keeping such reservations in mind, let us examine the broad trends shown in Table 1.1. It seems clear that cereal output per capita in rural areas did not increase in the 1970s to 1990s,⁶ whereas harvested area per capita in rural areas generally declined during the same period. An important observation is that output per capita in rural areas steadily increased in the 2000s and 2010s, owing to the increasing growth rate of output per harvested area, which can be considered a proxy for land productivity. Also, harvested area per capita in rural areas slightly increased after the turn of the century, presumably because of the increasing use of arable land for cereal production.⁷ According to the last row in Table 1.1, output per capita in rural areas increased by 35%, harvested area per capita in rural areas declined by 28%, and output per harvested area increased by 87% from 1961 to 2018. Thus, it is clear that the declining land–labor ratio was more than compensated for by increasing land productivity so as to boost labor productivity. Interestingly, this is similar to the development paths of South and East Asia in the past (Otsuka and Fan 2021).

The fact that land productivity has been increasing in recent years in SSA indicates that economic forces have been at work to promote the intensification of farming systems to increase crop yields in the face of the increasing scarcity of agricultural land.

2.2 Yield Trend of Cereal Crops in SSA

It is a mistake to assume that yield of cereal crops has been completely stagnant in SSA. As is shown in Fig. 1.2, it is true that cereal crop yield per hectare of harvested land had been either stagnant or grew only slowly from 1961 to around the turn of the century. The yield continued to stagnate in the case of sorghum and even declined in the case of millet in this century. As shown by Otsuka and Muraoka (2017), the yield of these crops did not appreciably increase in tropical Asia either, and hence, a yield gap between the two major regions did not emerge. Thus, there is little opportunity for SSA to learn technology from tropical Asia in millet and sorghum production. Therefore, any expectation that the yield of these crops will increase significantly in SSA in the near future is unfounded.

Fig. 1.2

(Source United States Department of Agriculture 2021)

Changes in average yield of major cereals in SSA (ton/ha), 3-year moving averages

Fig. 1.3

(Source United States Department of Agriculture 2021)

Changes in aggregate harvested area in SSA by major cereal crop, 3-year moving averages

The average wheat yield in SSA continuously increased, starting with 0.7 tons per hectare in 1961 and reaching nearly 3 tons per hectare in 2019. The yield of 3 tons is comparable to the average in other regions (Shiferaw et al. 2013). South Africa has the largest wheat harvested area, and its yield reached 3.6 tons per hectare in the late 2010s, which is much higher than in India. Wheat is grown by fully mechanized large-scale irrigated commercial farms in South Africa, leading to a wheat Green Revolution in this country. The wheat yield of smallholders in Ethiopia also grew, even though it was lower than 2.8 tons per hectare in the late 2010s.

It is noticeable that the yield of rice and maize increased from roughly 1.7 tons to 2.4 tons per hectare and from 1.5 tons to 2.1 tons per hectare from the turn of the century to the present. Whether this is an onset of the Green Revolution or temporary growth is a critical question. Although we are not sure if the initial yield growth of these crops will lead to sustainable growth in coming years, the thrust of this edited volume is that rice yield can continue to grow if proper government interventions, to be identified in this volume, are made to facilitate the rice Green Revolution.

How is the differential yield growth observed in Fig. 1.2 related to changes in harvested areas shown in Fig. 1.3? Several interesting phenomena can be noted. First, while the maize harvest area has increased sharply in recent years, the harvested area of millet began declining around 2010, and that of sorghum remained unchanged. These changes are consistent with the increasing trend of maize yield and the declining trend of millet yield. Second, the wheat harvested area has been small and has remained essentially constant. This indicates a limited area suitable for wheat cultivation in SSA, i.e., the cold climate in southern and highland parts of the continent. There is also no room for expanding irrigated large-scale commercial wheat farms in South Africa. Thus, we can hardly expect that wheat will be a major staple crop produced in SSA. Third, the paddy harvested area slowly increased up to 2005 and then expanded sharply, so that recently, it approached the harvested area of millet. There seems to be no doubt that rice has become a major staple crop in SSA.

2.3 The Increasing Importance of Rice

Table 1.2 shows the estimated total consumption,⁸ consumption per capita, total production, and net imports by major cereal crops in 1980 and 2018. It is clear that maize is the most important crop in terms of consumption and production. Both maize consumption and production more than tripled over the last 38-year period. Maize was marginally exported, but most countries in SSA were largely self-sufficient. Consumption per capita of maize increased by 16% from 1980 to 2018. Total and per capita consumption of milled rice increased much more dramatically; total consumption increased by 5.65 times, and per capita consumption almost doubled over a mere 38-year period.

Table 1.2 Consumption, production, and import of major cereals in SSA

Although milled rice production increased five times, net imports increased more sharply and accounted for 42% of total consumption in 2018. Evidently, the importance of rice in SSA has increased significantly in recent years. Wheat consumption increased significantly, although less dramatically than rice. Its production also increased but more slowly than consumption, resulting in huge net imports in 2018. Since the area suitable for wheat production is limited in SSA, we can hardly expect rapid wheat production growth and reduced growth of wheat imports. Although the production of millet and sorghum increased slowly, SSA is largely self-sufficient in these crops because of the declining per capita consumption. The importance of millet and sorghum declined.

As is shown in Fig. 1.4, rice production, expressed by the milled rice equivalence, has steadily increased for the last 60 years. The growth in rice production is primarily accounted for by an increase in the harvest area, as the trends of the two curves look similar, particularly until 2005. The gap between the two curves widened in the 2010s, suggesting that the area expansion no longer sustained production growth, thereby increasing rice imports from Asia. Thus, the increasing trend of rice imports cannot be reversed unless substantial yield growth is achieved. Considering the increasing importance of rice in production, consumption, and trade, it is an opportune time for African countries to pursue a rice Green Revolution.

Fig. 1.4

(Source United States Department of Agriculture 2021)

Changes in rice production, harvested area, and net imports in SSAFootnote

Production is milled rice equivalent.

3 Prospects for Future

3.1 Emerging Yield Gap

In order to examine the prospect of rice farming for the future, it is instructive to examine long-term paddy yield trends in the past and the yield gap between the most advanced regions and others and compare yield in SSA with that in Asia. We assume that if there is a yield gap between the advanced regions and others, and between SSA and Asia, there is room for less advanced regions in SSA to catch up with more advanced regions, including Asia. It is also instructive to compare the case of rice with maize to predict future development.

Figure 1.5, which shows the average paddy yield in SSA and India as well as the top five countries in SSA,¹⁰ provides valuable information. The average yield in India was roughly 1.7 tons per hectare in the early 1960s before the Green Revolution began, roughly the same as the average yield in SSA in the 1990s. Yield in India has been growing since then, whereas yield in SSA gradually increased this century. This increasing yield trend in SSA can be attributed, at least in part, to the Green Revolution in selected areas, judging from the fact that the average yield of the top five countries began increasing sharply from the early 1990s and approached the level in India in the 2010s. Their average yield of nearly 3.8 tons per hectare in 2019 is comparable to the average yield of about 4.1 tons per hectare in tropical Asia in the same year. There seems to be no doubt that the rice Green Revolution has successfully taken place in selected areas in SSA, particularly in irrigated areas.

Fig. 1.5

(Source United States Department of Agriculture 2021)

Changes in average paddy yield in SSA, top five countries,Footnote

Top five countries are Kenya, Niger, Senegal, Benin, and Mali.

and India (ton/ha), 3-year moving averages

It is also important to emphasize that the yield gap between the top five countries in SSA and the regional average has widened since 1990. This increasing gap indicates that the vast yield gap as of 2019 resulted from efforts to improve yield in the top five countries rather than the innate difference in yield between the top five and the other countries in the region. Consequently, there seems to be the possibility that less advanced regions may be able to catch up with advanced regions in SSA.

For comparative purposes, Fig. 1.6 shows the yield trend of maize in SSA and India. First, there was practically no yield gap between SSA and India from the 1960s to the mid-1980s, which indicates the small difference in agro-climate between SSA and India. Second, the maize yield in India began increasing in the late 1980s due to the Green Revolution, resulting in a yield gap of roughly one ton per hectare between India and SSA in recent years. This gap is substantially smaller than for rice, which is more than two tons per hectare. Third, the yield gap between the top five countries in SSA and India has disappeared in recent years,¹² indicating that the maize Green Revolution took place to a significant extent in advanced regions. Fourth, the yield gap between the top five countries and the average is comparatively small, which indicates that there is little room for less advanced regions to catch up with advanced regions in maize farming in SSA. Because improved maize varieties are highly location-specific (Smale et al. 2013), catching up may be more difficult in maize than rice production.

Fig. 1.6

(Source United States Department of Agriculture 2021)

Changes in average maize yield in SSA, top five countries,Footnote

Top five countries are Ethiopia, Zambia, Uganda, Mali, and Cote d’Ivoire.

and India (ton/ha), 3-year moving averages

We do not mean to argue that priority should be placed solely on the development of the rice sector, ignoring the maize sector. Considering the utmost importance of maize in SSA, the development of the maize sector must receive high priority. Our analysis strongly suggests that the establishment of productive technology must first be pursued in the case of maize, as argued by Otsuka and Muraoka (2017). In contrast, the dissemination of already established advanced technology to wider areas is an urgent issue in rice. This provides the basis for the main argument of this book: rice cultivation training is a vitally important entry point to the rice Green Revolution in SSA.

3.2 Changes in the Real Prices of Rice and Maize

Figure 1.7 shows that global rice production has continued to increase over the past several decades. Since more than 90% of rice is produced in Asia, the Asian rice Green Revolution significantly contributed to increasing rice production globally. While it is difficult to tell exactly when it took place, it seems that it has had substantial and sustainable impacts on rice production since the late 1960s. This was partly because it took a few decades to disseminate new technologies. Moreover, improved varieties, such as pest- and disease-resistant and drought- and flood-tolerant varieties, were successively developed (Evenson and Gollin 2003; Janaiah et al. 2005; Estudillo and Otsuka 2006; Emerick et al. 2016), which are likely to have contributed to sustainable growth in rice production in Asia. This book is concerned primarily with how to launch a rice Green Revolution in SSA, which is expected to increase the productivity of rice farming for a few decades, but not how to sustain it beyond that period. In order to sustain the Green Revolution over long periods in this region, continuous development and diffusion of improved rice production technologies and management methods will be required.

Fig. 1.7

(Source FAOSTAT 2019; World Bank Pink Sheet 2020)

World production and real prices for rice and maize in 2010 US dollars

As a result of the Asian Green Revolution, real rice prices continued to decline due to increasing rice production until the “food crisis” in 2008. The real rice price at around the year 2000 was merely one-third of the level around 1970. This sharp reduction in real rice prices indicates that the primary beneficiaries of the Green Revolution were rice consumers, including those in SSA. Rice farmers in SSA suffered from lower rice prices without receiving any benefit from improved productivity of rice farming, as well as rice farmers in Asia who failed to adopt improved technology due to unfavorable production environments (David and Otsuka 1994). These lower rice prices may have reduced incentives to develop and disseminate improved technologies in rice production in SSA.

The lower panel of Fig. 1.7 indicates that the real price of maize also declined from the 1960s to around 2005 because of the increasing maize yield and production. The real prices of rice and maize jumped in 1974 and 2008 despite only a slight reduction in global production due to speculation with incorrect expectations. The real maize prices have remained comparatively high in the 2010s.

If real rice prices decline or remain relatively low, reliance on cheap imports, rather than boosting production, can be a possible option for SSA. There are a couple of reasons that cereal prices, particularly rice prices, will increase. The first is climate change, which will increase cereal prices by 12–18% by 2050 (Rosegrant et al. 2021). Extreme weather events may also occur more frequently than before, likely leading to a temporary shortfall in production. Another potential threat is the increasing cost of food production in high-performing Asian countries, which depend on labor-intensive production methods due to small farm size. Unless farm size expansion and labor-saving mechanization occur, there is a fear that Asia will become a major importer of cereals that will drive up cereal prices globally (Otsuka et al. 2016a, b; Yamauchi et al. 2021).

Although it is challenging to predict cereal prices in the future, it seems safe to assume that they will not decline in the coming years. Thus, it makes sense to devote serious efforts to boosting rice and maize production in SSA by realizing the Green Revolution. It must be pointed out that, since SSA accounts for a small share of global rice production, the Green Revolution in SSA, even if successful, will not affect the international price of rice to a significant extent.

4 Conceptual Framework and Hypotheses

4.1 A Conceptual Framework

The rice Green Revolution involves the intensification of rice cultivation, which is defined as the intensive use of modern inputs, such as improved rice seeds and inorganize fertilizer, combined with improved cultivation practices. Paddy yield and profitability of rice farming are enhanced by such intensification. Some improved cultivation practices, such as proper seed preparation, fertilizer application, and pest and weed control, are also expected to improve paddy quality (JICA 2021). Although intensification usually means increased use of inputs, we would like to include appropriate harvesting, drying, and storing activities as a part of the intensification process, to the extent that these activities increase the value of output and profitability of rice farming. Figure 1.8 illustrates our conceptual framework, which explains how to achieve the rice Green Revolution through the intensification of rice farming.

Fig. 1.8

Note Intensification of rice cultivation is defined as the intensive use of modern inputs, such as improved rice seeds and inorganize fertilizer, combined with improved cultivation practices, including appropriate harvesting, drying, and storing activities

A Conceptual framework to achieve a rice Green Revolution through intensification.

We hypothesize that the chief development strategy ought to be a rice cultivation training program because it has proven to be highly effective in improving the productivity of rice farming, based on previous studies (Kijima et al. 2012; deGraft-Johnson et al. 2014). We can hardly expect a significant and sustainable improvement of rice productivity without improving cultivation practices, such as bund construction, leveling, weeding, water and pest control, and proper timing and spacing of transplanting, as is the case in Asia. Because these cultivation practices are knowledge-intensive, it requires training farmers to acquire an accurate understanding of these practices and ensure proper implementation to realize their full yield potential.

This emphasis on rice cultivation training does not imply that other factors, such as investments in mechanization and irrigation, are unimportant.¹⁴ On the contrary, these investments play critical roles in facilitating the intensification of rice cultivation. We postulate that mechanization, particularly the introduction of power tillers (two-wheel hand tractors), facilitates proper land preparation, which prevents the overgrowth of weeds by keeping even water depth, thereby inducing the intensive adoption of complementary cultivation practices, such as proper spacing of transplanting. Four-wheel tractors may not be appropriate for intensification because it is difficult to maneuver heavy machines in small muddy paddy fields and move across paddy fields without agricultural roads. The use of power tillers and four-wheel tractors is also expected to lead to the extensification of rice farming, i.e., cultivation of formerly unused land and conversion of non-rice land to paddy land, owing to the efficiency in land preparation, including construction and plowing of new paddy fields.

Like Asia, irrigated areas tend to be more intensively cultivated throughout the year, as the availability of irrigation water increases the benefit of intensification, and they are thus far more productive than rainfed areas in SSA (David and Otsuka 1994; Balasubramanian et al. 2007; Kajisa and Payongayong 2011; Nakano and Otsuka 2011; Cassman and Grasssini 2013; Nakano et al. 2013). Because irrigated paddy area accounts for a minor fraction of the total paddy area in SSA,¹⁵ whether a rice cultivation training program effectively improves productivity in a rainfed area is a critical question to be investigated in this book. We may expect that, since bunding and leveling improve water control, their adoption may enhance productivity in rainfed farming.

It is often argued that milled rice produced in SSA cannot compete with higher-quality imported Asian rice (Diako et al. 2010; Demont 2013; Demont et al. 2017). We believe that the correct timing of harvesting and proper drying of harvested paddy and, probably more importantly, proper milling machines and proper grading of milled rice are critically important in the quality improvement of milled rice. Reardon et al. (2014) report that the introduction of improved milling machines triggered revolutionary changes in the quality of milled rice in Asia. Improved milling technology, especially removing stones and other impurities, combined with the grading of rice and differential pricing of paddy based on the quality, may stimulate proper seed-bed preparation, fertilizer application, and pest and weed control as well as the adoption of appropriate harvesting and post-harvesting activities to produce and deliver high-quality paddy (Ibrahim et al. 2020; Kapalata and Sakurai 2020; Ogura et al. 2020). Production and delivery of high-quality paddy, which is regarded as a part of intensification in this study, will, in turn, affect the rice marketing activities.

4.2 Hypotheses

Following our introduction of the conceptual framework above, we would like to postulate four key hypotheses to be tested in this book. While the impact of the rice training program on the intensification of rice farming is expected to be significant, one may wonder if it will differ between the shorter and the longer run, between rainfed and irrigated areas, and between training participants and non-participants. We therefore propose the following hypothesis:

Hypothesis 1: Rice cultivation training programs have a significant impact on the intensification of rice farming, thereby improving paddy yield and the profitability of rice farming, (a) in both the shorter and longer run, (b) in both rainfed and irrigated areas, and (c) not only for training participants but also non-participants through information spillovers.

The purpose of mechanization is commonly assumed to save labor and draft animals in Asia (e.g., Hayami and Ruttan 1985). In SSA, where land preparation depends mainly on manual labor, however, the introduction of power tillers and four-wheel tractors makes it possible to carry out land preparation more thoroughly and speedily. The effects of the adoption of power tillers and four-wheel tractors could be different because power tillers can be more easily maneuvered in muddy paddy fields and moved across fields without destroying bunds. Thus, it will likely be profitable to use power tillers for both intensification and extensification and four-wheel tractors particularly for extensification. Regarding the impact of tractorization, it seems worth testing the following hypothesis:

Hypothesis 2: The adoption of power tillers contributes to both the intensification and extensification of rice farming, whereas that of four-wheel tractors contributes primarily to the extensification.

There is no question that the presence of irrigation facilitates the intensification of rice farming. While it is relatively easy to assess the impact of irrigation on the productivity of rice farming on farmers’ fields, it is more difficult to assess the rate of return on investment in irrigation facilities because of the difficulty in collecting the data on the cost of construction and maintenance and in predicting future benefits which are affected by increased production efficiency and future rice prices. In our view, the extent of increased production efficiency critically depends on the provision of rice cultivation training programs in conjunction with the irrigation projects. The estimation becomes more difficult if we attempt to include general equilibrium effects on the development of related activities, such as rice milling and trading, and the delivery service of inputs. Thus, our tentative hypothesis on the impact of irrigation investment is as follows:

Hypothesis 3: While investment in a large-scale irrigation scheme may have modest expected returns, its economic viability increases if proper rice cultivation training on modern inputs and improved management practices is provided and also if the general equilibrium effect is taken into account.

The quality of milled rice depends on rice varieties, the timing of harvesting, drying of paddies, and the quality of rice milling machines, e.g., the use of destoners and color sorters. Thus, rice millers can play a key role in improving the quality of rice because they can introduce improved machines to produce high-quality milled rice and because they can affect the quality of paddy grown by farmers by introducing grading and differential pricing.¹⁶ Traders may also introduce grading and differential pricing of milled rice if markets become conscious about milled rice quality. Therefore, it seems reasonable to postulate the following hypothesis:

Hypothesis 4: Rice millers play the role of innovators in the improvement of the quality of rice by installing improved milling machines and enhancing farmers’ incentives to produce high-quality paddy. Rice traders are also expected to provide incentives to farmers to produce high-quality paddy by offering quality-based pricing when markets become conscious about rice quality.

5 Structure of the Book

This book consists of six parts: Part I is concerned with an overview of extensification, intensification, and the Green Revolution in sub-Saharan Africa; Part II examines the impact of rice cultivation training programs; Part III explores the effect of mechanization, irrigation, and improvement of rice quality and milling technologies; Part IV summarizes findings of this study and proposes strategies to achieve a full-fledged rice Green Revolution in SSA.

After this introductory chapter, we review the literature on the role of agricultural extension in Chap. 2 to show the broad context in which the various case studies of the impact of management training on rice farming were undertaken. Since we believe that the rice cultivation training program is the fundamental activity required to realize a rice Green Revolution, four chapters are devoted to assessing the program. Applying a randomized controlled trial, Chap. 3 confirms the sustainable impacts of the training program and dissemination of improved cultivation practices from training participants to non-participants in an irrigated area in Cote d’Ivoire. Chapter 4 demonstrates the significant impact of the training in rainfed areas and irrigated areas in Tanzania. Furthermore, it shows the sustainable impact of training and the technology being successfully disseminated by training participants to non-participants. Chapter 5 shows the evidence of the sustainable impacts of a rice cultivation training program and the passing on of improved cultivation practices from training participants to non-participants in a rainfed area in Uganda. Chapter 6 provides evidence that the rice training program effectively enhances the productivity of rice farming even in an unfavorable rainfed area in Mozambique, where farming without applying improved seeds and chemical fertilizer is practiced.

In Part III, we begin by reviewing the literature on the impact of agricultural mechanization and irrigation on rice farming intensification in Chap. 7. The effect of tractorization in Cote d’Ivoire is dealt with in Chap. 8 and in Tanzania in Chap. 9. Both chapters demonstrate that the adoption of power tillers promotes both the intensification and extensification of rice farming. Furthermore, Chap. 9 finds that adopting four-wheel tractors has had little impact on the intensification, whereas the adoption of draught animals significantly enhances the intensification.

As explained previously, estimating the rate of return on large-scale irrigation investment is not easy, as it involves the complex calculation of associated costs and benefits. Furthermore, it is difficult to assess the general equilibrium effects of irrigation investment on related activities, such as rice milling and trading. Yet, Chap. 10 attempts to estimate the rate of return on the Mwea Irrigation Scheme in Kenya by asking a hypothetical question of what the rate of return would be if investment in irrigation facilities were made now. According to the estimation results, the rate of return is unlikely to be high unless rice prices are assumed to be relatively high. Moreover, because of the possible complementarity between improved cultivation practices and the availability of irrigation water, well-designed training on appropriate rice cultivation may significantly enhance the rate of return to large-scale irrigation investments. Chapter 11 assesses the efficiency of small- to medium-scale irrigation management in Senegal and finds that relatively large-scale irrigation is more efficiently managed than smaller ones.

Both Chap. 12, in which we attempt to assess the efficiency of introducing improved rice milling machines in Mwea in Kenya, and Chap. 13, where we attempt to assess the impacts of providing market information and rice miller’s pricing policies to farmers on the marketing and production behavior in Ghana, support the hypothesis that rice millers play a key role in improving the quality of rice. The implication is that rice millers ought to be a focal point of rice value chain upgrading rather than a holistic approach to improve the entire value chain without a clear focus.

The concluding chapter, Chap. 14, proposes a strategy for a full-fledged rice Green Revolution in SSA based on in-depth case studies reported in Chaps. 3–6 and 8–13. Specifically, we conclude that there is no reason to doubt the success of the widespread rice Green Revolution in SSA as long as rice cultivation training programs, coupled with the introduction of power tillers and irrigation investment, are offered as a way of promoting the intensification of rice farming.