Practical innovation: Partnerships between Scientists and Farmers

Farmers have been experimenters since the beginning of agriculture. Hunters and gatherers had long since learned to use fire as a means of stimulating the growth of tubers and other food plants, and of grass to attract game. Plant selection began when people found they could encourage favored fruiting trees by clearing their competitive neighbors, but the first steps toward intensive plant breeding were taken when an individual, probably a woman rather than a man, deliberately sowed a seed from a high-yielding plant somewhere near the dwelling and observed it grow to maturity. In Europe and Asia, wheat and rice naturally attracted experimental attention. Because they are predominantly self-pollinating, selection produces rapid improvements and the rare crosses provide new material, often with exciting potential. The first bread wheat, a natural cross between emmer wheat and a wild goat grass, was noticed by farmers as early as 8,000 years ago; it was the kind of exotic cross that modern genetic engineers strive for and that is announced in the press, today, as a miracle variety. Farmers continued to domesticate new species, but most attention was devoted to the local selection and adaptation of the existing relatively small number of cereals and livestock. Experimentation also resulted in new whole systems of agriculture— swidden, rice terracing, home gardens, irrigated agriculture, the Mediterranean Trio of wheat, olives, and vines, the Latin American multiple cropping of maize, beans, and squashes, and, in many parts of the world, various forms of integrated crop-livestock agriculture. As is evident from their writings, the Romans analyzed the structure and functions of agricultural systems in a scientific manner. They also described the process of experimentation. Marcus Terentius Varro, who wrote a treatise on agriculture in the 1st century BC, urged farmers to both “imitate others and attempt by experiment to do some things in a different way. Following not chance but some system: as, for instance, if we plough a second time, more or less deeply than others, to see what effect this will have” (Hooper and Ash, 1935). The great agricultural revolution of Britain in the late 18th century was led by farmers.

Competition between Livestock and Mankind for Nutrients: Let Ruminants Eat Grass

As we contemplate the challenge of feeding more than 8 billion people —more than three quarters living in developing countries —the even greater challenge will be feeding their grandchildren. Consideration of competition between livestock and mankind for nutrients must include both near-term food needs and long-term sustainability of agricultural production systems. Producing more livestock products at the expense of eroding the natural resource base is not an acceptable solution. Livestock have been denigrated as both competitors for food and degraders of the natural resource base for food production. These often emotionally argued allegations against livestock generally do not stand up to objective analysis. Livestock arc most often complementary elements of food production systems, converting otherwise unused feed sources to highly desired food and livestock products such as leather and wool. Moreover, well-managed livestock are positive contributors to the natural resources base supporting balanced agricultural systems. In this chapter, the following points are addressed from the perspective of current and future role for livestock in feeding 8 billion people: . . . • Growing demands for human food and livestock feed • Domesticated food-producing animals • World livestock production systems • Human food preferences and requirements • Dietary requirements and conversion efficiencies • Contributions of science to livestock improvement . . . The overarching issue is the difference in the current and future role for livestock in developed and in developing regions. Less than 11 percent of the global land mass of 13.3 billion hectares is cultivated; the remainder supports permanent pasture, 26%; forest, 31%; and other nonagricultural uses, 32% (U.N. data as cited by Waggoner, 1994). The concerns about competition between livestock and mankind for nutrients center primarily on grains and legumes grown on arable land. Even the most avid vegetarians have little taste for the forages and other herbaceous materials from pasturelands, forests, roadsides, and fence rows that arc consumed by livestock. Since the 18th century, the amount of land cultivated has increased from approximately 0.3 to 1.5 billion ha (Richards, 1990, as cited by Waggoner, 1994). This increase in cultivated land has primarily come at the expense of forest and grasslands.

Animals and the Human Food Chain

The argument that the population explosion presents a serious challenge to the ability of the world to feed itself and a serious threat for the recovery potential of the planet has been well rehearsed. The Reverend Thomas Malthus, an ordained minister of the Anglican church and a Fellow of Jesus College, Cambridge, stated in his famous essay nearly 200 years ago that “population, when unchecked, increases in a geometrical ratio. Subsistence increases only in an arithmetical ratio” (Malthus, 1798). Since 1950 the human population has doubled, and U.N. projections indicate that it is set to reach about 8 billion by the year 2020 and 9.5 billion in 2050. The trajectory of the sigmoid model predicts that the current exponential increase will stabilize around a figure of 10 billion by 2100. A different model is the J-shaped curve, in which exponential growth during favorable conditions is followed by a dramatic, if recoverable, crash resulting from density-dependent destruction of the environment. Whichever model will apply in future, population growth will be checked somehow, depending on the influence of food security, fertility control, and socioeconomic factors. Many of the chapters in this book have focused on land resources and the opportunities that exist for improvements in crop production. While a substantial component of the planet’s biomass consists of vegetation, it would be unwise to underestimate the direct and indirect contributions of livestock to food security. In this chapter I consider the impact of scientific advances on animal production and the human food chain and examine the reasons there are strong dissenting voices raised against the adoption of some technologies and to what extent such concerns affect progress. The Brundtland Commission (1987) defined food security as secure ownership of, or access to resources, assets, and income-earning activities to offset risks, ease shocks, and meet contingencies. In other words, not everyone is intended to be a subsistence fanner, but everyone must possess the means to acquire an adequate diet. For most of the world’s population this is a rational interpretation of food security, with the prosperous producing that which is surplus to indigenous needs and the less developed areas benefiting from that surplus’s distribution to areas of scarcity.

What Limits the Efficiency of Photosynthesis, and Can There Be Beneficial Improvements?

Over the past 35 years a great deal has been learned about the mechanisms of photosynthesis, ranging from the ultrafast reactions involved in the initial capture of photons to the slower processes of carbon metabolism. Today our knowledge of photosynthesis and its molecular mechanisms is enormous, so much so that it is difficult for one person to absorb all the information. This is not necessarily a bad thing, since what we have achieved is sufficient information to appreciate the complexity of the “photosynthetic engine” and to identify the main factors that ultimately regulate its efficiency. In this chapter I summarize those areas of photosynthesis research with which I am reasonably familiar and, in so doing, address the question posed by the chapter title. As Blackman (1895a,b) pointed out, the rate of photosynthesis initially rises as the light intensity is increased and then levels off to a plateau. This plot is often referred to as the rate v PFD curve, where PFD stands for Photon Flux Density. Over the years rigorous analyses of the slopes of the rate v PFD curve have been made to obtain a value of the quantum yield (usually expressed as the number of quanta or photons required to produce one molecule of oxygen or to fix one molecule of carbon dioxide). With a few exceptions, the value obtained for a wide range of “non stressed” organisms and plants supplied with excess CO2 is about 9 or a little more (Björkman and Demmig, 1987; Walker, 1992). Bearing in mind that one molecule of oxygen evolved or carbon dioxide fixed is a 4e/4H+ process, then a value of 8 would he consistent with the “Z-scheme” model proposed by Hill and Bendall (1960). In this scheme, each electron is excited twice, first by photosystem two (PSII) and then by photosystem one (PSI). In this way, 8 photons are used to drive 4e/4H+ from water, through PSII and PSI to NADP.

Energy for Agriculture in the Twenty-first Century

Adequate food supplies and a reasonable quality of life require energy —both noncommercial and commercial forms. Energy is a prime mover of economic growth and development. Although the linkages between energy and development are complex and still imperfectly understood, energy undoubtedly fuels economic development. And the developing countries where most of the population growth is occurring face an energy crisis of staggering proportions. An ample energy supply is not an automatic guarantee of smooth economic advancement, social progress, or stability, but it is, indisputably, their essential precondition. The future of our increasingly interdependent world will thus be very much influenced by the success or failure of the developing countries to ensure a sufficient and sustainable flow of energy (Smil and Knowland, 1980). The global inequity in the use of commercial fuels is familiar. About 1.5 billion people live in countries where the per capita consumption is less than 7 gigajoules (GJ) y-1, and another 1.1 billion consume only 7-20 GJ y -. Let’s translate this into more meaningful terms: 7 GJ is the equivalent of about 180 1 of diesel fuel —or about 0.5 1 per day to cover all human needs, such as food production and cooking, shelter, heating, and clothing. Millions and millions of rural inhabitants use virtually no commercial fuel. Clearly, no one can achieve a desirable quality of life (QOL) with so little energy available (Leach, 1979). Many studies have related GNP and energy use, but scholars debate the correlation with QOL. When one considers that energy is required to produce all the basic needs of humans, it seems apparent that a relationship as shown in Figure 5.1 may exist. Morrison (1978) carried this concept a step further by expressing QOL as a function of energy use. At low levels of energy use (quadrant III), he hypothesized that basic need satisfaction is linearly related to energy use. As the amount of energy increases (quadrant II), two paths were hypothesized. Option A projects a linear relationship between QOL and energy use, whereas option B suggests an optimum QOL at a moderately high level of energy use, followed by a deterioration of QOL due to environmental degradation at excessively high energy use rates.

The Economies of Food

People expressing concern about the environmental resource basis of human life often take a global, futuristic view (see, e.g., Kennedy, 1993). They emphasize the deleterious effects that growing population and rising consumption would have on our planet in the future. They express worry that the increasing demand for environmental resources (such as agricultural land, forests, fisheries, fresh water, the atmosphere, and the oceans) and the resulting impacts on ecosystem services (such as regenerating soils, recycling nutrients, filtering pollutants, assimilating waste, pollinating crops, and operating the hydrological cycle) would make civilization unsustainable. This book is, at least in part, a response to this thought. Although the global, futuristic emphasis has proved useful, it has had two unfortunate consequences: it has encouraged us to adopt an all-or-nothing position (the future will be either catastrophic or rosy), and it has drawn attention away from the economic misery that is endemic in large parts of the world today. Disaster is not something for which the poorest have to wait: they face it right now, and nearly 1 billion people go to bed hungry each night, having been unable to escape from something that can be called a poverty trap. Moreover, in poor countries, decisions on fertility and on allocations concerning education, child care, food, work, health care, and the use of the local environmental resource base are in large measure reached and implemented within households. In earlier work (Dasgupta, 1993, 1995a, 1995b, 1996, 1997), I have tried to show that the interface that connects the problems of population growth, poverty environmental degradation, food insecurity, and civic disconnection should ideally be studied with reference to myriad communitarian, household, and individual decisions, or, in other words, that if we are to reach a global, futuristic vision of the human dilemma, we need to adopt a local, contemporary lens.

Needs for Food: Are We Asking Too Much?

The Royal Society has in recent years taken a great interest in the growth of the world’s population and has been represented at the two big international congresses on this subject, in Delhi and in Cairo (Graham-Smith, 1994). According to U.N. projections, in 20 year’s time the world population will be between 7.5 and 8.5 billion (Demeny, 1996). There does not seem to be much controversy about these figures. On the other hand, when it comes to the question of whether it will be possible to feed these 8 billion people, opinions diverge widely between optimists and pessimists. McCalla (1995), the director of the Agriculture and Natural Resources Department of the World Bank, in a very illuminating discussion of the controversy, has said, “The economists are always wrong,” presumably because they have to deduce future trends from those of the past. It seemed to us that the best way to make a useful contribution is to look at the subject and assess the possibilities from an objective scientific point of view. The Royal Society has done this twice in the past, with two discussion meetings: one on Agricultural Efficiency (Cooke et al., 1977) and the other on Technology in the 1990s: Agriculture and Food (Blaxter and Fowden, 1985). Now, 10 years on, it is time to have another go, widening the scope of the recent discussion meeting “Land Resources: On the Edge of the Malthusion Precipice?” The late Kenneth Blaxter, in a scries of lectures called “People, Food and Resources,” published in 1986, recalled a quotation from Friedrich Engels, writing in 1844 about the Malthusian dilemma: “Science advances in proportion to the knowledge bequeathed to it by the previous generation and thus under the most ordinary conditions grows in geometrical progression — and what is impossible for science?” (my italics).

Productivity, Poverty Alleviation, and Food Security

Most observers agree that, barring catastrophe, the global population will number more than 8 billion by 2025. There is, however, less agreement about the consequences for food security. Some, for example, Brown and Kane of the World Watch Institute (Brown and Kane, 1994), argue that there will be widespread shortages of foodstuffs, accompanied by higher global prices. Others, like Alexandratos of the Food and Agriculture Organization of the United Nations (FAO) (Alexandratos, 1995), claim that production will match rising demands and that prices will continue to decline in real terms. All agree, however, that the world’s poor, especially those in the poorest countries, will be without adequate food. This chapter links food security with poverty and argues that increased productivity in agriculture is the most effective way for the poor to achieve food security. What is food security? The International Food Policy Research Institute, IFPRI (IFPRI, 1995) defines food security as “economic and physical access at all times to the food required for a healthy and productive life.” Food security has two dimensions: the availability of food and access to food. Availability depends on production, and, while the debate about global availability continues, the view in this chapter, like that of the FAO, is that adequate food will be available globally at real prices roughly comparable to those prevailing in the 1990s. (See Dyson, 1996, p. 167, for perhaps the latest systematic study holding this view.) To achieve food adequacy, the major assumptions here are that research will continue to turn out the elements of improved technologies and that Eastern Europe, especially Russia and Ukraine, will move closer to its potential as a food supplier. Lack of access to food because of poverty, however, is a major challenge. Some people in the developed world and in higher-income developing countries do not have access to food, but policy changes could resolve that problem; certainly, such societies have the resources. This is not the case for the poor in the world’s poorest countries; for them, the combination of individual and societal poverty severely limits access to adequate foodstuffs.

Prospects for Engineering Enhanced Durable Disease Resistance in Crops

Plants have evolved a battery of defense mechanisms that in aggregate provide protection against a wide range of potential viral, bacterial, fungal, and other pathogens encountered throughout the plant life cycle. However, in the artificial setting of agriculture, disease, although the exception, can be costly and even devastating. Crop diseases have played significant roles in human history, exemplified by the widespread starvation and mass emigration triggered by the failure of European potato crops in the mid-nineteenth century as a result of late blight. Today, the use of pesticides, breeding for resistance, and integrated pest management provide important tools for reducing crop losses to pre-and postharvest diseases. However, agrichemicals are expensive, prohibitively so for many fanners in developing countries, and there are increasing concerns about environmental load from their intensive application. Likewise, major disease resistance (R) genes are in many cases not durable, resistance breaking down within one or two seasons as a result of selection pressure on the pathogen population, and most breeding efforts now rely on combinations of minor resistance genes, each giving partial protection. For a number of important diseases, such as take-all of wheat, there is no effective genetic resistance. Population growth, migration to cities, desertification, and climate change all now contribute to an urgent need to secure diversified food production against disease losses. In this chapter I discuss the prospects that genetic engineering of disease-resistance mechanisms can contribute to durable, broad protection and hence underpin enhanced crop productivity. Plants have a number of performed physical and chemical defensive mechanisms that help protect against the myriad potential pathogens to which plants arc exposed (Osbourn, 1996). However, superimposed upon this preexisting protective armory, plants respond to the perception of pathogen attack by activation of inducible defense mechanisms (Lamb et al., 1989; Staskawicz et al., 1995). Many of the most important crop diseases involve specialized interactions between pathogen and host. Interactions between specific plant cultivars and defined physiological races or strains of potential pathogens are described as compatible (host susceptible, pathogen virulent) or incompatible (host resistant, pathogen avirulent).

Rubisco, the Key to Improved Crop Production for a World Population of More Than Eight Billion People?

Despite great advances in understanding of photosynthesis in crops, photosynthesis research has contributed little to improvement of crop production in the past. Does it have a future role in the task of feeding a world of 8 billion? In this chapter I argue that modification of the primary carboxylase of photosynthesis (Rubisco) promises very significant increases in potential crop yields. Plant breeding over the past three decades has produced remarkable worldwide increases in the potential yields of many crops, most notably improvements in the small grain cereals of the “green revolution” (Beadle and Long, 1985; Evans, 1993). Potential yield is defined as the yield that a genotype can achieve under optimal cultivation practice and in the absence of pests and diseases. What are the physiological bases of these increases? Following the principles of Monteith (1977), the potential yield (Y) of a crop at a given location is determined by . . . y = St- εi- εe- η/k (1) . . . where St is the integral of incident solar radiation (MJ m-2), εi the efficiency with which that radiation is intercepted by the crop; εe the efficiency with which the intercepted radiation is converted into biomass; η the harvest index or the efficiency with which biomass is partitioned into the harvested product; and k the energy content of the biomass (MJ g-1). St is determined by the site and year, while k varies very little across higher plant species (Roberts et al., 1993). Potential yield is therefore determined by the combined product of three efficiencies, each describing broad physiological properties of the crop: εi, εe, and η. εi is determined by the speed of canopy development and closure, and by canopy longevity and architecture. εe is a function of the combined photosynthetic rate of all leaves within the canopy less crop respiratory losses. In the context of equation 1, increase in potential yield over the past 30 years has resulted almost entirely from large increases in η.