An e-publication by the World Agroforestry Centre
AGROFORESTRY A DECADE OF DEVELOPMENT 
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An e-publication by the World Agroforestry Centre |
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AGROFORESTRY A DECADE OF DEVELOPMENT |
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section 2 Chapter 3 M. S. Swaminathan Introduction From the dawn of civilization, sustainable food security has been a major human goal. FAO defines food security as "physical and economic access to food for all people at all times". I have repeatedly stressed the need for enlarging this concept to cover all aspects of balanced nutrition as well as clean drinking water so that all human beings have an opportunity for the full expression of their innate genetic potential for physical and mental development (Swaminathan, 1986). Also, I have pointed out that enduring food and nutrition security can be built only on the foundation of ecological security, i.e. the security of the basic life-support systems of land, water, flora, fauna, and the atmosphere (Swaminathan, 1981). It is in this context that I wish to assess the role of agroforestry systems in helping us to achieve sustainable nutritional and ecological security. Thanks to new technologies that emphasize the cultivation of genetic strains of crops that respond to irrigation and good soil-fertility management, many tropical and subtropical (developing) countries in Asia and Latin America have made good progress in food production since the mid 1960s. Many traditionally food-deficit or food-importing countries have become self-sufficient and even food-surplus countries. What is even more significant is that increases in food production have come largely from increases in productivity rather than increases in cultivated area. Because many developing countries, particularly those of south and south-east Asia are population rich but land poor, this is an important gain. Today world grain stocks have increased to more than 450 million tonnes. Despite such a satisfactory global situation, scientists and planners are worried. For them, increasing the pace of food production to keep pace with unabated population growth in the tropics and subtropics is still an unfinished task. Although most countries of the world are in the process of demographic transition, the progress toward the final stage of this transition is lagging behind dangerously in Africa, the Indian subcontinent, Latin America, the Middle East, and south-east Asia (Brown and Jacobson, 1986). It is predicted that between 1980 and 2000, world population will increase by 1.7 billion. Ninety percent of this growth will occur in the developing countries. This tremendous increase will require at least 50-60 percent greater agricultural output than in 1980. What then should be the appropriate strategy for increasing food production? Now it is sufficiently clear that any increase in food production has to come primarily from raising the productivity of currently tilled soils rather than from bringing new land resources into farming. In fact, a large portion of currently tilled marginal areas will have to be phased out of agriculture for economic and ecological reasons. Land for agriculture is a shrinking resource. Because some land is being taken out of production all the time and diverted to uses such as roads, housing, and industry, health care of the soil is a priority task. The carrying capacity of land in many developing countries is already overstretched. According to a recent FAO study, 54 of 117 developing countries did not have sufficient land resources to meet the food needs of their 1975 populations at low levels of input use (Higgins et al, 1983). These critical countries, covering an area of 2.2 billion ha, in 1975 had 278 million people in excess of the population supporting capacity of the land. By AD 2000, at the same level of inputs, the number of critical countries will increase to 64 and the population in excess of the land's potential carrying capacity may be over 500 million. Even if input use is raised to the intermediate level, which may not be easy considering the external indebtedness of many developing countries, 36 countries will still be in a critical situation with 141 million people above the carrying capacity of the land. Modern agricultural production technology has raised the hope that hunger can be eliminated and the carrying capacity of the land increased through better use of cubic volumes of soil, water, and air. Nevertheless, the ecological sustainability and economic viability of new technologies are increasingly at stake. The rising populations of humans and animals, with their ever expanding food, fodder, and feed needs, exerts great pressure on the stabilizing elements of agro-ecosystems. As productive land becomes scarce, marginal fanners are pushed into fragile crop lands and forest areas unsuitable for modern agriculture. If the present trend of population growth persists, forest and pasture lands will be further reduced. Figure 1 projects these relationships for the Himalayas, a very delicate agro-ecosystem (Shah, 1982).
A major cause of soil erosion is deforestation. Table 2 indicates the huge gap between deforestation and tree plantation in the tropics where the problem is most acute. The World Resources Institute has estimated that 160 million hectares of upland watershed in the Himalayas and Andean range, and in the Central American, Ethiopian and Chinese highlands, have been seriously degraded due to human interference (WRI, 1985). Cherrapunjee, once the wettest area in the world and covered by dense tropical forest, is now practically devoid of vegetation. Overcutting for fuelwood and overgrazing in arid and semi-arid areas, combined with non-sustainable resource-use patterns triggered by commercial greed or careless technology, have accelerated desertification. Such activities directly affect agriculture. Extensive deforestation results in raised river beds, which reduces their water-carrying capacity, and consequently their irrigation potential. In India, for example, the National Commission on Floods has projected that an irrigation potential of almost 60,000 ha may be lost every year because of siltation.
Shifting cultivation, long practised all over the tropical highlands, has also contributed to deforestation. At the beginning of this century, shifting cultivation cycled in 30-40 years, but now it cycles in as few as 3-5 years due to increased population pressure. An important offshoot is the reduced availability of fuelwood — a major source of energy in the rural areas of developing countries. If the gap between harvesting and tree planting remains as it is today, fuelwood shortage may become an even more serious problem than food availability. A Study Group of the Planning Commission of the Government of India estimated in 1982 that to meet the fuelwood demand in AD 2000, at least 3 million ha need to be planted every year with fast-growing fuelwood trees (Swaminathan, 1982). The increasing distance between villages and forests has increased the time needed for fuelwood collection, thus depriving farm women and children of time which could have been utilized in other productive activities. Although the evidence is still inconclusive, extensive cutting of the tree cover may contribute to the increased level of carbon dioxide in the atmosphere. The accompanying increase in global temperature could directly affect agricultural production. That the global mean surface temperature actually increased during the last 100 years has recently been proved by comprehensive estimates of temperature based on calibrated ocean data and land measurements (Jones et al, 1986). A series of papers contained in the publication State of the World —1987, published by the World Watch Institute, provides a grim picture of the emerging global ecological scenario. Climate change carries a global price tag of $200 billion for irrigation adjustments alone in the coming decades (Brown, 1987). It is obvious that the maintenance of tree cover is of utmost importance for ecological and economic sustainability of food-production systems. Agroforestry involving the integrated cultivation of woody perennials, crops, and animals provides one answer to our quandary. A typical agroforestry system allows symbiotic economic and ecological interactions between the woody and non-woody components to increase, sustain, and diversify the total land output. Some of the dominant agroforestry systems are: (a) shifting cultivation, (b) taungya afforestation, (c) homegarden, (d) silvopastoral, (e) agrisilvicultural, and (f) windbreaks and live fences (Nair, 1985). Farming systems that incorporate perennial trees and shrubs have the advantage of producing fuelwood, fruit, fodder, and other products along with annual crops. In addition, they decrease the farmer's exposure to seasonal environmental variations and, over the long-term, maintain and improve soil health. The following sections give a brief account of agroforestry systems, some recent successes, and the potential of these systems for increasing food and environmental security.
Different patterns of agroforestry were common in the early days. For many upland farmers, agroforestry was a way of life. Shifting cultivation, for example, is believed to have originated in the Neolithic period around 7000 BC (Sharma, 1976). In this system, still common in many hilly areas of tropical Asia, Africa, and Latin America, trees and agricultural crops are arranged sequentially in time and space. Its sustainability in the past was due to low population pressure and availability of large tracts of undisturbed forests. Today, shifting cultivation promotes soil erosion and land degradation. Inasmuch as we have alternative methods of soil fertility restoration, shifting cultivation is no longer necessary. Homegarden, or homestead, is another common agroforestry system (Soemarwoto, this volume). In this system, tall trees are intercropped with medium shrubs and short annual crops to produce a variety of foods and green manure besides reducing soil erosion. Intercropping in coconut and oil palm plantations is also common. Farmers generally plant smaller trees such as coffee and cacao, and banana underneath the palms. To arrest land degradation due to shifting cultivation, a fairly successful system called taungya was developed in the mid-1800s in Burma. In this system, the government gave land to shifting cultivators and allowed them to grow trees and agricultural crops together. When the tree canopy closed and precluded further agricultural cropping, farmers were shifted to another site. Meanwhile, the abandoned site developed into a fully-fledged forest. Taungya was later adopted by many countries of Asia, Africa, and Central America, (see King, this volume.) Many of these systems have now given way to subsistence agricultural systems in several developing countries. Because subsistence farming practices are not ecologically sustainable and often not economical, interest in agroforestry is increasing.
With the growing realization that agroforestry is a practical, low-cost alternative for food production as well as environmental protection, forest departments of many countries are integrating agroforestry programmes with conventional silviculture. Forest research institutes and agricultural research centres are increasingly developing programmes for agroforestry research, training, and education. The UN Conference on Desertification held in Nairobi in 1977 stressed the significance of agroforestry systems for meeting the food, fuel, fodder and fertilizer needs of rural communities without causing ecological harm. The establishment of ICRAF in 1977 was a significant milestone in the history of agroforestry research. ICRAF for the first time provided a global professional organization for stimulating and supporting scientific and developmental interest in silvopastoral, "silvo-horticulturaT, agrisilvicultural and other systems of land management. Agrosilvopastoral systems Among recent developments, the most important has been the realization of the importance of multipurpose, woody, leguminous trees and shrubs in low-input fanning systems. These legumes, such as various species of Leucaena, Sesbania, Gliricidia, Acacia, and Prosopis, are capable of providing the food, fodder, fertilizer and fuel needs of rural populations. The trees also diversify income, dominate over weeds, reduce soil erosion, and improve soil structure and fertility. Many of these species are widely adapted. For example, Sesbania can tolerate a wide range of soil environments — saline, alkaline, and waterlogged. Many agrosilvopastoral systems have been proposed in recent years. Among these, alley farming is one of the most important. In this system, food crops are grown hi alleys formed by hedgerows of trees or shrubs (see Kang and Wilson, this volume). The hedgerows are cut back at the time of planting crops and are kept pruned to prevent shading the crops (Figure 2). Pruned foliage is allowed to decompose in the alleys and the nutrients released increase grain yields of interplanted crops (Table 3). The foliage is also used to feed livestock. Simultaneously, the trees provide many other by-products such as fuelwood and stems for staking viney crops.
Multi-level plantations and homegardens Multi-level plantations and homegarden systems, common in smaller landholdings and designed to increase food production, are fairly analogous to a rain forest with a multilayered canopy. The systems and their component crops vary with the location. In the humid tropics, plantations of coconut, oil palm, and rubber have increased during the last few years due to greater demand for vegetable oils and rubber products. New opportunities have become available with the development of high-yielding hybrids between tall and dwarf coconuts, which have a potential similar to that of oil palm. During the initial and later years, palms in the plantation do not make use of all the available sunlight, space, and water (Nair, 1979). These plantations, therefore, offer opportunities for intercropping (Figure 3). Cacao in Malaysia, cassava in India, banana in Jamaica, and pineapple in the Philippines are now commonly intercropped with coconut. A significant amount of cacao in Sri Lanka is now grown under rubber.
Farm forestry In several countries, some very successful farm forestry projects have begun to increase the rate of reforestation and to augment the supply of timber, fodder, fruit, and fuelwood. In the Gujarat State of India, the Forestry Department started a project in the early 1970s. The system was .gradually accepted by fanners because it was less labour-intensive and labour requirements were spread over the year. Tree fanning with eucalyptus has now become so popular that irrigated, fertilized fields are also being used for this purpose (CSE, 1985). Today, at least 10 percent of Gujarat's farming families are involved in farm forestry. Similar success has been achieved in Haiti, Kenya, Senegal, and Nepal (WRI, 1985). Such tree monocultures on farmland may not, however, always represent a major ecological advantage. Trees such as eucalyptus do not provide fodder or mulch and may consume large quantities of water. There is also the risk that such programmes may increase rural unemployment. Hence, proposals for monoculture with tree species have to be carefully examined for their potential impact on soil, water, and employment. In the Philippines, an industry-related agroforestry system has become popular. In the project launched by the Paper Industries Corporation of the Philippines (PICOP) in 1967, 20 percent of the land is used to raise agricultural crops and 80 percent for tree farming with Albizia falcataria, a fast-growing tree for paper pulp in an eight-year rotation (Veracion, 1983). The scheme provides farmers with a continuous source of food and income. PICOP guarantees the purchase of wood, provides help in acquiring land, assists in obtaining loans and Albizia seedlings, and furnishes technical help (see also Arnold, and Spears, this volume). The scheme has been able to meet all its objectives — to meet pulpwood requirements, to curb deforestation, and to increase the small fanner's income. Agroforestry in arid and semi-arid areas In arid and semi-arid environments, agroforestry systems help to provide greater insurance against weather abnormalities. Many multipurpose trees such as Prosopis cineraria, Zizyphus rotundifolia, Casuarina spp., Tecomella undulata, Acacia tortitis, and Dalbergia sisoo thrive in arid areas. Crops accompanying these trees may not show any significant reduction in grain yield (Government of India, 1986). Perennial shrubs such as Sesbania and Cajanus cajan also show promise for producing food, fodder, and fuelwood. Alley cropping can be successfully practised in many wetter areas. Windbreaks and live fences are other options available in agroforestry for dry areas. Leucaena leucocephala, when planted as a windbreak, increases the grain yield of agricultural crops and moisture availability in soil by reducing surface run-off and evaporation. In Niger, millet yields increased by 23 percent when neem trees were planted as windbreaks. Vast tracts of sand dunes have been stabilized in Senegal by planting trees in and around the farms. In Maroua, Cameroon, Cassia siamea trees were planted across lowland plains as a shelterbelt to reduce soil erosion and increase agricultural output. Although the shelterbelt reduced soil erosion, yields of sorghum and cotton, the principal crops in the region, decreased, particularly in a 30m-wide strip on either side of the tree rows. This was not due to competition between the trees and crops but to the combined effect of reduced air turbulence and undisturbed heating of the ground raising the temperature. Therefore care needs to be taken to leave sufficient gaps in the tree fences to allow optimal air movement. Agroforestry in problem soils and wastelands Large areas in the tropics are affected by salinity, alkalinity, acidity and waterlogging. Unscientific land-use practices have led to a further increase in the area affected by toxicities and deficiencies. Such degraded lands can often be reclaimed by agroforestry while providing poor farmers with some income. Many species of trees can grow well in these problem areas where most agricultural props cannot. The various species of Sesbania, for example, can grow successfully in saline, alkaline, and even waterlogged soils. In the coastal areas of Gujarat, India, extensive areas have been planted to Prosopis juliflora. In West Bengal, India, the government has leased out marginal degraded forest wastelands to landless farmers. These farmers are provided sufficient incentives and inputs to practise agroforestry, leading to increased tree plantations in the area. Large tracts of eroded wastelands in the Loess Plateau of China have been reclaimed by planting trees and using legumes as ground cover. Cheaper techniques such as planting tree seedlings in pits to which gypsum has been added can also be very useful in expanding agroforestry. There is a need for formulating land-use policies based on sound principles of ecology and economics in such areas. The Indian example, where the government has formed a National Land-Use and Wasteland Development Council headed by the Prime Minister, can be followed in countries with similar problems.
We are currently witnessing a good deal of optimism about what agroforestry can accomplish for food production and environmental protection. Generally, most countries in Asia and Latin America are able to meet their food requirements.,In contrast, most sub-Saharan African nations face complex technological problems arising from the fragility of soils, scarcity of water, diversity of crops and pests, and climate variability. More than 40 percent of Africa's people live in countries where grain yields are lower than they were a generation ago. The loss of tree cover in closed forests and in savannas is extensive. In many countries wood collection for fuel and other uses exceeds the sustainable yield of remaining accessible forests. A recent World Bank study of seven West African countries covering five rainfall zones showed that in ecozones having the lowest rainfall, agricultural and fuelwood demands equal or exceed sustainable yields (World Bank, 1985). Another finding was that in all countries and in all zones, the sustainable carrying capacity of the forests was much less than that of croplands and grazing lands (Table 4). Africa today is witnessing gradual shifts in its ecological zones. The recent drought and consequent famine in Ethiopia and other countries made Africa the focus of world attention and concern. In tourist literature, Ethiopia is often described as a country with 13 months of sunshine. It is ironic that agriculture, which is essentially a solar-energy-harvesting enterprise, is so poor in these countries. Restoring the African tree cover is essential to the restoration of the hydrological cycle and to the recovery of agriculture (Brown and Wolf, 1985). Widespread introduction and promotion of agroforestry can go a long way towards sustainable resource management and ecological and economic rehabilitation of Africa.
Agroforestry can also play a greater role in reclaiming wastelands and wasted lands and in increasing food production in problem soil areas. It should also be appropriate in maintaining the long-term soil health of poor or average quality lowland soils. Agrisilvicultural or agrosilvopastoral systems such as alley farming can become very successful. Windbreaks and silvopastoral systems can help in mitigating drought-associated risks in arid and semi-arid regions. The crucial question, however, is whether land-use practices should be changed to accommodate agroforestry in presently good quality, fertile, highly productive, resource-rich farms. In this age of a highly dynamic market and consequent changes in farming systems, introduction of trees into these areas may lead to inflexibility and many management problems. However, it will be desirable to encourage tree plantation on farm boundaries, canal bunds, and poor patches of the farmland. In view of the enormous potential of agroforestry for promoting sustainable production, there is a need to identify and remove the technological and socio-economic constraints limiting the spread of agroforestry. Some of the important challenges that require immediate attention are now discussed.
Biological constraints To sustain agroforestry, it is important to strengthen our research efforts. Such low-cost and ecologically sound technologies should not receive low inputs of scientific and financial resources. There is an immediate need to extensively survey existing agroforestry systems to determine the interaction between component species, to classify the trees used, and then to refine the systems in view of soil, climate, and socio-economic limitations. Clearly, an interdisciplinary approach is warranted. Earlier, agroforestry systems were predominantly based on economic principles. Future systems, however, will have to overcome physiological (canopy structure), biological (pests and diseases), and ecological (sustainability and environment protection) constraints besides being economically sound. Detailed studies on the competition and complementarity between trees and understorey agricultural crops for solar radiation, space, and soil factors are needed. The enormous experience gained in intercropping annual crops can be very useful. The tallest component of agroforestry systems, the tree, should have foliage tolerant of strong light and high evaporative demand; the shorter components should have foliage adapted to shade and relatively high humidity. It is very important to consider the microclimatic changes that agricultural crops have to face under the trees. The entire process of selection and breeding of crops and crop varieties should take this into consideration. Similarly, agroforestry systems should avoid below-ground competition for water and nutrients by ensuring that component species have non-overlapping root systems. The incorporation of deciduous trees such as Dalbergia sissoo into agroforestry systems can often be very useful. The natural abscission of leaves during autumn enriches the soil while the availability of solar radiation under the tree increases. Growing short-duration, high-yielding crops during this period of abundant sunshine- and nutrients will be very productive. Alternatively, we should consider the use of growth regulators to induce partial defoliation of the trees when the radiation requirement of the understorey agricultural crop is at its peak. This may also help reduce the labour required for pruning in systems such as alley cropping. However, studies on the feasibility and practicality of such methods are needed. Diversity in agroforestry systems is very important for their ecological sustainability. Extensive plantations with a single strain of LeucaIena leucocephala in the Philippines and elsewhere has led to severe psyllid pest epidemics, damaging more than 50 percent of the trees (Lapis, 1986). Brewbaker (1985, this volume), drew attention to the genetic vulnerability to pest attack of single variety plantations of Leucaena leucocephala. Similarly, overdependence on a single genotype of the stem-nodulating Sesbania rostrata may lead to pest and disease outbreaks. Therefore, it is necessary to identify and describe more nitrogen-fixing tree species as well as genotypes of S. rostrata. Many such trees have been catalogued by the National Academy of Sciences (1979) and ICRAF (1986). Eucalyptus plantations have significantly increased in recent times due to their importance in pulp and paper manufacture. In many areas these can be replaced by fast-growing kenaf, Hibiscus carmabinus, another excellent source of raw material for paper manufacture. Lack of suitable germplasm can delay future research and development efforts in agroforestry. National, regional, and global germplasm banks for preserving seeds of tree species are needed. Ecological sustainability of agricultural practices can be promoted only by spreading awareness that conservation is development. Pest and disease control through agroforestry has been rarely studied. Today, integrated pest management involving non-overlapping pest crops and conservation of natural enemies is very important. Trees can, for example, provide a physical barrier to flying insects. In Samoa, there is a conspicuous reduction in cacao-leaf damage caused by the root beetle, Andoretus versutus, when it is intercropped with trees (Newton and Thomas, 1983). The role that multipurpose tree species such as neem (AzadiracIhta indica), known to be an effective pest-control agent, can play in agroforestry should be determined. There is also a need to resolve silvicultural problems. It is important to raise the ecological adaptation of tree crops. A major problem with many tree species is the difficulty of establishing them and their slow initial growth. Some species need scarification of seeds for germination. We must examine alternative methods of establishment and propagation. Foresters have considerably improved the techniques of vegetative propagation for hardwood trees. These can be applied to nitrogen-fixing trees as well. Success in vegetative propagation and clonal selection will allow production of a large and continuous supply of plantation stock. The stem- and root-nodulating shrubby legume Sesbania rostrata (Dreyfus and Dommergues, 1980; Dommergues, this volume) has the capacity to grow and fix nitrogen in waterlogged soils. The possibility of transferring this stem-nodulating habit to other legume species by genetic engineering should be explored to increase their adaptability. Many tree crops, such as eucalyptus, could be unsuitable for agroforestry simply because their foliage and roots produce allelopathic toxins. Physiological and biochemical studies to control the production of these toxins should be initiated. Last, methods should be developed to reduce the time taken to develop agroforestry systems. Research in agroforestry is long-term and does not promise major returns in the short run. Mistakes in agroforestry can, therefore, be costlier than mistakes made in agriculture.
The adoption of the agroforestry system of land use requires fundamental changes in approaches to farming. For a subsistence farmer this may involve, besides a change in farming practices, a change in diet or a change in marketing and labour-input requirements. Recent experience with Green Revolution technology has demonstrated the roles human ecology and sociology play in the acceptance and spread of technologies. We need to study the various socio-economic constraints and design appropriate strategies to convince the farmer that the short- and long-term payoff in adopting agroforestry will be considerable. To promote agroforestry as a sustainable method of increased food production and environmental protection, we should develop and introduce the three mutually supportive and harmonious packages:
Success in cereal production in Asia and Latin America during the last two decades was due to the availability of mutually reinforcing agricultural packages (Swaminathan, 1986). The three major components of a symphonic agricultural system are briefly described below. Package of technology The proposed technology should aim to achieve the highest output possible per unit of land, water, time, and labour while disallowing any depreciation in the basic agricultural assets of land, water, flora, and fauna. The "cafeteria" approach, in which farmers can choose based on their capabilities and requirements, should be proposed. For the subsistence farmer, the proposed agroforestry technology should not only produce food, fodder, fertilizer and fuelwood, but some cash income. For the market-oriented farmer, the technology package should operate at still higher efficiency, both at the production and post-harvest level. A package of information should be built in to suggest the kinds of trees and agricultural crops, best combinations, management practices, costs and benefits, markets, and sources of financial and technical assistance. In Africa, 75 percent of the food grown and eaten is produced predominantly by women. The proposed technology should also take note of the sex-related roles in food production. Package of services Equality of opportunity to appropriate technology should be the foundation of all agricultural extension and development planning. Designing and developing packages of essential services so farmers can take advantage of the new agroforestry technology is extremely important. Both government and private agencies should be active in providing seeds, seedlings, fertilizers, and, very important, credit. Regional seed and seedling banks should be established to ensure the timely availability of seeds and seedlings for farmers. Modern propagation methods can be used to produce quality stocks. The last service, credit, is essential because the payoff in agroforestry starts several years after the introduction of the scheme. Governments need to evolve innovative policies for an effective and timely input supply scheme. Package of government policies No agricultural or agroforestry technology can remain productive and sustainable without government support. One major area that requires government action is land reform. Agroforestry is a long-term practice so it will not be surprising if tenant farmers fail to adopt it. In an agroforestry project in the Philippines, it was noted that part-owners of land used their own area on the site for contour-hedges, indicating their acceptance of agroforestry but a reluctance to establish trees on land they did not own (Kent, 1985). The concept of land reform should be enlarged to include not only ownership but regulations to prevent abuse of land. In parts of Africa, livestock reform to enable controlled grazing is equally important. Unscientific land-use practices have led to degradation of large tracts. In each country, there is a pressing need to set up a national task force for designing and promoting agroforestry systems, which should design appropriate components of agroforestry for all ecozones. This should be supported by suitable training programmes at various levels. The technique of training should be learning by doing. Mass media such as local language papers, radio, and television should be actively involved. Software should be developed for agroforestry education and communication. Extension agencies should have skilled and motivated workers to successfully protect and promote the interests of individuals and society in agroforestry. The available food-grain surpluses in the world give us increasing opportunities to diversify agroforestry systems based on long-term sustainability criteria. For example, to reclaim eroded, marginal soils, one should avoid growing annual food crops in the new agroforestry systems. Subsistence farming families in remote isolated areas, hard pressed to earn their daily bread, can be persuaded to adopt ecologically sound land-use practices only if they are assured of the staple grain they need. Food security for the poor must first be ensured before the promotion of ecological security. Governments will have to build visible grain stocks in habitats characterized by fragile ecosystems. In countries where governments do not have their own stocks, special programmes such as "Food for scientific land use" or "Food for agroforestry" development could be initiated. In the case of better-off farmers, opportunities for producer-oriented and remunerative marketing becomes essential to stimulate and sustain their interest in agroforestry. Here, input-output pricing policies become crucial. Enough incentives, such as support price for wood and other tree products, should be provided.
Eternal vigilance is the price of stable agriculture. The greatly increased population and its ever expanding needs for food and fuelwood in this century threaten agricultural stability. Political and commercial greed, the genuine needs of the poor for fuel and fodder, inappropriate technologies, and the absence of a systems approach in the design and implementation of agricultural and industrial projects in ecologically fragile areas, have all contributed to increased environmental deterioration. B.F. Skinner (personal communication) has rightly emphasized:
It is time that we devote greater attention to economically and ecologically sustainable agricultural production systems where present economic progress and prospects for survival will not be in conflict. Fortunately, agroforestry systems are characterized by this happy blend and help us to exploit in a sustainable manner cubic volumes of soil and air and thereby give farmers the maximum return from the available soil, water, nutrient, and sunlight. There is now an opportunity to design more efficient and ecologically sustainable agroforestry systems by putting the large food grain stocks of today to intelligent use. Agroforestry systems designed to overcome physiological, biological, ecological, and economic constraints can help to enhance production efficiency. We therefore need both greater support for agroforestry research and greater integration of agroforestry research into the mainstream of farming-systems research. Stimulating and helping to sustain a symphonic agroforestry system based on appropriate blends of political will, professional skill, and peoples' action will be a major challenge for ICRAF in its second decade.
The author is deeply indebted to Dr P.K. Aggarwal of the Multiple Cropping Department of IRRI for assistance in compiling material for this paper.
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