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12.5 The technological challenges of agricultural growth
Limiting land and water degradation
Chapter 11 highlighted the extent of degradation and our lack of understanding as to its full implications for crop productivity and sustainability. Two aspects of soil conservation are becoming increasingly clear. The success of conservation measures is highly dependent on farmers receiving crop yield and economic benefits in the first or second season after implementation (FAO, 1989a). In dryland areas such gains will commonly arise more from improvements in physical structure leading to enhanced soil moisture levels and retention (Shaxson, 1992) than from the reduction of soil nutrient losses, although the latter are important (Stocking, 1986).
Failure to meet these requirements, together with institutional weaknesses, accounts for the failure of many past conservation techniques and projects, which were either very labour intensive or required costly mechanical operations. Hence they were often not profitable in the short or even the medium term and, moreover, they were costly to maintain. Farmers therefore seldom adopted the conservation techniques, or did not maintain the conservation structures after the end of the project. The success stories of today, which in a sense are success stories of the past since they commonly use or build on indigenous technologies, are consistent with these conclusions (see, for example, Reid, 1989; FAO, 1991a; Kerr and Sanghi, 1992).
The above conclusions and observations carry several important messages for technology development to achieve long-term sustainability. First, soil conservation strategies, research and extension should concentrate on measures with no or low external capital requirements, so that they are more appropriate for resource-poor farmers in marginal areas that are projected to be under increasing pressure. Second, provided the appropriate institutional support is given (see Chapter 13), known techniques could help to boost or stabilize yields. Third, these techniques are not widely used and could benefit a much larger area. A large part of the drylands in subSaharan Africa and in Asia could gain from them through both increased and more stable yields and by more frequent cropping. Also slopelands in the high rainfall tropics could gain from techniques better adapted to their particular constraints.
There are also other implications for research. The focus should be on biological rather than mechanical approaches to soil conservation which, as with vegetative barrier techniques or with systematic crop and residue management, either retain soil particles and eventually build up natural terraces or protect the soil surface from rain impact and erosion. Attention should also be focused on techniques that combine soil erosion limitation with wider land degradation control functions, such as the use of leguminous live mulches. The International Agricultural Research Centres of the CGIAR, notably CIAT, ILCA and IITA have been supporting national research efforts by collecting and testing suitable legumes for forage or mulch purposes, but the current national and international efforts are inadequate relative to the task and their potential contribution to sustainability.
Box 12.2 Managing the "four waters"*
From 1949 to 1980, the irrigated area in China increased by 32.7 million ha and currently covers 46.7 million ha. Due to problems of scarce water resources and the limited possibility of further expansion, the rate of growth has fallen significantly in recent years. In response, Chinese engineers and agronomists have developed an innovative method of water management, known as the concept of the "four waters", which refers to a comprehensive control and supervision of groundwater, surface water, soil moisture and rainfall for agricultural production. The objective of this approach is to produce two crops per year over the largest area possible with limited use of surface water. The basic innovation of the "four waters concept" is the dynamic control of the aquifer. Whereas traditional horizontal drainage keeps the groundwater table below a certain level to avoid waterlogging and secondary salinization, dynamic groundwater management, in addition to controlling the water table, uses the aquifer as storage. Dynamic groundwater management keeps the level of the aquifer within a specified range, which is defined by hydrological and agricultural requirements, and takes into account the constraints posed by salinity hazards and the need for efficient energy use. The "four waters concept" has been tested extensively in the Nanpi experimental station in Hebei Province and in a pilot project of 23600 ha. The results have been positive. The implementation of this water management approach showed that large areas of saline alkaline land could be reclaimed, and land which was previously unsuitable for irrigation due to groundwater salinity, has been cultivated. Moreover, rice yields increased by 110 percent: from 3.7 tonnes/ha to 7.8 tonnes/ha. Multi-annual hydrological simulation demonstrates that with only 550 mm average annual rainfall, as much as 43 percent of the dry season irrigation requirements can be met without groundwater mining or external water imports.
*Source: Shen and Wolter (1992).
Finally, there is the problem of salinization. As noted in Chapter 11, irrigated land is being lost and substantial areas suffer reduced yields through salinization. The most common causes are inadequate drainage, rising water tables because of water seepage from distribution canals, and excessive application rates. Consequently, the standard corrective actions have been additional drainage and canal lining, both of which can be costly. In the future, however, part of the solution seems likely to lie in conjunctive use of surface water and groundwater and the parallel use of canal and tubewell systems, with the latter providing vertical drainage as well as secondary irrigation. Experience in China, for example, has shown that a more holistic approach to water management, what is called there the "four waters concept", can prevent salinization and reclaim salinized land (Box 12.2).
Promoting integrated plant nutrition systems (IPNS)
IPNS aims at maximizing the efficiency of plant nutrient supply to crops through better association of on- and off-farm sources of plant nutrients and ensuring sustainable agricultural production through improved productive capacity of the soil. Such systems may significantly reduce needs for mineral fertilizers, because they provide timely and sufficient supplies of plant nutrients, and reduce as far as possible plant nutrient losses in cropping systems. Adoption of IPNS has the potential of increasing the profitability of mineral fertilizer use (FAO, 1993a).
Progress towards achieving these broad objectives must be viewed in the various ecological and economic contexts of agriculture in developing countries. Firstly, there are situations where plant nutrients are mined from the soil because extractions by crops and losses of plant nutrients through erosion, leaching and volatilization exceed the low level of plant nutrient supply. Here IPNS will assist in achieving a better balance of nutrients, the intensification of cropping systems with limited use of external inputs, better recycling of local sources of nutrients and, above all, a drastic reduction of nutrient losses.
Secondly, there are situations where plant nutrient efficiency is low, even with significant supplies of nutrients from various sources. In these cases, IPNS could improve efficiency through the appropriate combination of plant nutrient sources and cropping techniques. In most cases, this low efficiency is due to an unbalanced supply of plant nutrients (often too much nitrogen relative to other nutrients) or to another limiting factor such as micronutrient deficiency and physical or chemical constraints of the soil. IPNS seeks to relieve such constraints depending on the availability of resources (plant nutrients, equipment, energy, adapted varieties and irrigation).
Thirdly, there are situations where losses of plant nutrients are polluting the environment because of excessive or improper management of plant nutrient supplies. Examples are nitrates in surface and groundwater, phosphates in surface water and nitrous oxides and ammonia in the atmosphere. IPNS could reduce this type of pollution by both increasing plant nutrition efficiency and reducing plant nutrient losses.
Fourthly, there are arid and semi-arid areas where the maintenance of soil organic matter is crucial for efficient plant nutrient management, for maintaining soil permeability and waterholding capacity, and for the development of deep rooting systems capable of exploiting water stored in the soil. One challenge of IPNS is to produce sufficient biomass in order to restore to the soil the organic material lost during crop cultivation. In mining the reserves of soil plant nutrients, farmers reduce the capacity of their soils to produce biomass and cause the soils to lose organic matter. However, the mineralization rate of the soil organic matter is rapid when the soil temperature is high, and the biomass production, when plant nutrition is not a limiting factor, is directly related to the availability of water. Therefore, in the semi-arid tropics it may be difficult to restore the organic matter content of a degraded soil.
In the humid tropics, leaching of plant nutrients, erosion and acidification, and immobilization of plant nutrients in the soil may hamper the efficient supply of nutrients to plants. Additionally, competition of weeds and pressure of pests are important factors decreasing such efficiency. However, crop production, biomass production, and crop diversity are higher and the effect of temperature on the mineralization of soil organic matter is generally lower, than in the semi-arid tropics. Climatic risks are also low as compared to semiarid areas and the natural conditions are generally more favourable for agricultural intensification. Under such circumstances, IPNS will then have to address rather diversified levels of intensification. The upgrading of the soil fertility is easier than in the semi-arid or arid tropics because the production of biomass is higher. Limiting plant nutrient losses is more complex than in semiarid tropics because the overall quantity of plant nutrients involved is higher and the pressure of the factors causing these losses is also higher.
In the absence of water constraints in irrigated areas, the potential for plant nutrient efficiency is high. However, the efficiency of the use of plant nutrients is often quite poor because of poor control of nitrogen losses in the cropping system or unbalanced fertilization. IPNS in irrigated areas faces special problems since the use of crop residues has to be carefully regulated to avoid the development of diseases and the leaching of plant nutrients. However, fixation of nitrogen is possible either directly through traditional flooding irrigation (blue algae, azolla) or when irrigation takes place through sprinklers in mixed cropping or in relay cropping systems. IPNS in irrigated areas mainly focuses on improving plant nutrient efficiency, as maintaining soil organic matter content is simpler than in rainfed areas because production of biomass is generally high.
The efficiency of nitrogen use is a major problem in IPNS. Fixation of atmospheric nitrogen may provide significant quantities of nitrogen to the cropping system if water, phosphorus and sulphur are available. However, nitrogen biofixation cannot cover all nitrogen requirements except at low levels of intensification. There is a wide range of free-living soil bacteria that extract nitrogen from the atmosphere and make it available for plant growth. There are other bacteria, notably rhizobia, which live symbiotically with plants in small nodules (swellings) on their roots, receiving sugar from plants and providing in return nitrogen that they have taken from the atmosphere. The latter have been exploited by man for many years and sustained cropping systems in Europe and other parts of the world before the discovery of mineral fertilizers in the nineteenth century. In China, Thailand, Vietnam and other Asian countries, the alga Anabaena azollae, which lives symbiotically with the water fern Azolla, has sustained rice cropping for centuries by providing much of the nitrogen required.
The challenge at present is to exploit conventional techniques in combination with methods of genetic engineering to improve nitrogen availability and widen the range of plants and environments that can benefit. Current natural or managed plant/microbe systems in good rainfall areas can provide 20 60 kg of nitrogen per hectare, sufficient to sustain cereal yields of around 1 tonne. This could be raised by 25 percent by the year 2010. Conventional plant breeding techniques may assist to obtain better efficiency through varieties using plant nutrients more efficiently, or with stronger root systems avoiding losses through leaching. Varieties tolerant to soil constraints (salinity, lack of oxygen, free aluminium) will also benefit more than traditional varieties from plant nutrient supply.
IPNS is likely to make a significant contribution to crop production growth and to the achievement of sustainable agricultural systems over the period to 2010. Nevertheless, one should not underestimate the difficulties facing IPNS in the short to medium term, and also not overestimate the gains in the long term. Lack of livestock and labour will be a major constraint in some areas, as many smallholders cannot keep sufficient livestock to generate the required amounts of manure (up to 10 tonnes or more per hectare) or cannot provide the large labour input for collecting and spreading it. Where land constraints are severe, it may be impossible with current or foreseeable technologies to achieve or sustain high yields with only recycling or biofixing techniques for plant nutrient supply (Norse, 1988).
China has been in this situation for several decades. In spite of its efficient systems for organic residue recycling and biological nitrogen utilization, since about 1950, staple food production has become increasingly dependent on mineral fertilizers, making China the largest user of mineral fertilizers in the world. In spite of the efforts in China to improve further the efficiency of organic residue use, this trend seems likely to continue, reinforced by the increasing shortage of labour for the collection and application of organic manures. The production projections of this study suggest that several other countries or areas face the same dilemma as China.
Expanding the opportunities for integrated pest management (IPM)
The past agricultural performance carries with it the burden of mistakes arising from our previous lack of knowledge regarding pesticide toxicity, their persistence in soils and water, their accumulation through food chains and their impact on both non-target and target species. Some of the costs of these mistakes are to be seen in human mortality and morbidity, in damaged ecosystems and in the increase of pesticide resistance. There are now over 450 injurious species of arthropods that have developed resistance to one or more pesticides because of repeated applications (Georghiou and Lagunes-Tejeda, 1991). Resistance is also increasing in plant pathogens and weeds.
Following research showing the growing damage to human health and ecosystems from pesticide use, FAO spearheaded efforts in the mid-1960s to develop and implement the concept of integrated pest management (IPM). Initially, progress was slow since an understanding of predator-prey systems and other key aspects of ecosystems had to be built up. But in the past 10 to 15 years the success stories have grown and the concept has become more comprehensive. IPM now brings together five mutually enhancing control approaches.
· Pest control using crop rotations, intercropping and other
management methods.
· Host plant resistance.
· Biological control using natural methods or introducing new
enemies of the pests.
· Selective use of pesticides, preferably biopesticides, in
conjunction with pest population monitoring and the
establishment, where possible, of economic thresholds for
pesticide use.
· Plant health programmes, including plant quarantine.
FAO's extensive experience in Asia with the Intercountry Rice IPM Programme adds an additional dimension: namely that of farmers becoming managers and experts in their own fields. Through "Farmer Field Schools", they learn how to grow a healthier crop, to conserve natural enemies of crop pests, and to use the appropriate pesticide where needed only.
Chapter 11 outlined the increasing pest pressures envisaged for future agricultural growth, notably because of the intensification of production. It noted that although total pesticide use may continue to grow, this will occur at a lower rate as compared with the past and that application rates, environmental persistence and toxicity levels of pesticides will be lower in the future. These prospective developments are likely to come about because of the growing political, technical and farmer support in developing countries for IPM, and against the excess pesticide use of the past.
In pursuing the further development and implementation of IPM, priority should be given to the crops accounting for the bulk of pesticide use: cotton, maize, rice, soybeans, fruit and vegetables. All have a potential for wider IPM implementation though IPM cannot be effective for the full range of major pests. The FAO rice IPM programme has reached some 600000 farmers in Asia, cutting their pesticide applications by up to two-thirds, increasing yields and lowering costs of production. The number of trained rice farmers in Asia is expected to surpass I million before the end of the century, but this still represents a small fraction of the approximately 90 million rice farmers who could benefit from this programme's approach.
Although prospects for the other major crops are also good, experience thus far has been less favourable. The experience with cotton is mixed, with some countries achieving substantial reductions in pesticide use but others still increasing such use. Nonetheless, a more effective sharing of international experience could achieve widespread reductions by 2010 and lower cotton's dependence on pesticides.
As indicated in Chapter 11, the relatively high value of vegetables and the agronomic conditions under which they are grown, commonly lead to the heavy use of toxic pesticides. FAO is trying to stimulate action in this area through a regional vegetable IPM programme for Asia which is based on the lessons from the rice IPM programme mentioned above. However, the benefits of this programme and of various national initiatives are unlikely to have a major impact in the near future unless the problem receives much higher priority.
Progress has been made with the use of biocontrol agents, i.e. living or dead organisms (bacteria, fungi, insects, viruses, nematodes and protozoa), but mainly in the developed countries and commonly for glasshouse conditions. The most widespread biopesticide is Bacillus thuringiensis which, for example, is very effective against some cabbage pests, but is only used on a minor proportion of developing country production. In Brazil, however, a baculovirus is being used on about 1 million ha of soybeans to control the velvet bean caterpillar, a major pest of soybeans.
In spite of its demonstrated benefits, however, IPM is not a panacea or a complete alternative for all conventional plant protection methods. Its success depends on a number of natural, social and economic conditions. It requires appropriate, i.e. precise timing and sequencing of its various control measures. It therefore needs well-trained farmers and a well-functioning extension system with diverse pest monitoring facilities and early warning systems, etc. This places considerable demands on research and extension staff, as well as on farmer's capabilities. The high labour intensity required at both the farm and extension service level, could reduce the competitiveness of IPM vis-à-vis traditional high-external input systems in the near future as opportunity costs for labour are increasing in many developing countries.
Water development and water saving
Chapter 11 presented a perspective view of growing competition for water, a competition that agriculture has lost in some developed countries (for example on the Texas high plains in the USA) and seems destined to lose in some developing countries. The projected expansion in irrigation is therefore dependent on a number of technological developments that increase the efficiency of water capture or water use, particularly the following:
Box 12.3 Emerging irrigation technologies: LEPA and surge irrigation
The low energy precision application (LEPA) method of irrigation consists of a low-pressure moving irrigation system, such as a modified centre pivot system or linear-move system, where sprinkler heads are replaced by drop tubes which deliver water to the soil surface. The crop response to this system of irrigation is similar to the response to stationary drop installation with closely spaced emitters. Saline water can be used without damage to foliage under this system. It maximizes irrigation efficiency with low pressure nozzles near the ground, and the application efficiency could be as high as 90 percent (Fangmeier et al., 1990). It was reported that the average amount of water per hectare by Texan farmers dropped 28 percent between 1974 and 1978 because they adopted LEPA (Poster, 1989).
Surge flow irrigation is defined as the intermittent application of water to furrows or borders creating a series of on and off periods of constant or variable time spans. Usually water is alternated (switched) between two irrigation sets until irrigation is completed. The switch is accomplished with a surge valve and an automatic controller. Surge flow greatly reduces the intake at the top of the field because the opportunity time is much less than under continuous flow method. It is reported that efficiency of irrigation could be improved to an average of 70 percent or more. In the USA, the effectiveness of surge irrigation as a water conservation measure is demonstrated by its rapid growth and acceptance by farmers.
· Steps to safeguard the existing irrigation infrastructure through the soil conservation measures discussed earlier that will slow down the siltation of canals and reservoirs, and the actions to stop salinization and to rehabilitate saline land that are described later.
· The introduction of techniques, pricing policies and institutional changes that raise water use efficiency.
· Improvements in irrigation design and technologies to raise the efficiency and lower the costs of operation and maintenance.
· Expansion of the use of marginal quality water including brackish water and municipal wastewater.
· Removal of technical constraints to conjunctive use of surface water and groundwater resources.
Irrigation is the largest user of fresh water, yet irrigation water use efficiency can be as low as 40 percent (Kandiah and Sandford, 1993). Consequently, even a 10 percent improvement in water use efficiency can release a substantial volume of water for other uses and delay the onset of competition. The substitution of marginal for high quality water can have similar benefits. Several semi-arid countries in the Near East region already use treated sewage effluents for irrigation, releasing high quality water for other purposes. Many of the technical solutions have been produced and implemented in the developed countries, but adoption has been slow in most developing countries, mainly because of their high cost and complexity. Most of them are overhead irrigation systems involving sprinklers, and a range of micro-irrigation systems that are twice as efficient as surface irrigation. The more recent techniques such as low energy precision applications (LEPA) can be 90 percent more efficient than surface irrigation, as well as permitting the use of saline water (Box 12.3). They are being adopted in some developing countries, such as Morocco, but are unsuitable replacements for the bulk of present irrigation because the latter consists mainly of surface systems involving complete flooding for paddy rice, or furrow irrigation. The principal opportunity for the latter seems to be surge flow irrigation (Box 12.3), but this generally needs to be adapted to the farming conditions in developing countries. Such solutions could have an appreciable impact on non-flood irrigation schemes well before 2010. For the rest, the immediate task is applied research to improve flood irrigation, and to adapt sprinkler and micro-irrigation systems more closely to developing country conditions. Given the long gestation period for the completion and implementation of such research, lisle benefit can be expected before 2010.
In the past, attention has been focused on the health risks that can be posed by irrigation systems, through malaria and the spread of bilharzia, for example. Conjunctive use of water, however, presents an opportunity not only to reduce the competition for it but also to help reduce the most widespread threat to health in many rural communities, namely the lack of potable water. Irrigation canals and tubewells are increasingly recognized as a relatively safe source of drinking water, yet technologies and irrigation system design seldom take this into account. Research and technology development are urgently needed to determine the design requirements for dual-purpose systems, to identify treatments to safeguard health, and to adapt existing techniques and equipment to satisfy these requirements.
Raising livestock productivity
The projections pose a number of technological challenges for the livestock sector itself and for those supporting it with feedgrains, high-protein feeds, processing services and other inputs. The challenges differ between the land dependent commodities like ruminant meat, and those which are becoming increasingly separated from land, such as eggs, pig and poultry meat which are increasingly produced by intensive systems dependent on concentrate feeds and located in pert-urban areas or areas with good access to urban markets. The former tend to be resource constrained and supply driven, and in many cases are exerting growing pressures on the environment through overgrazing. The latter are increasingly able to side-step resource constraints because market conditions enable producers to purchase feed concentrates and the best available production and processing technologies. They also may place unsustainable burdens on the environment through poor waste disposal.
The main challenges are to compensate for the lack or poor quality of land through measures to raise pasture and rangeland output and improve management systems; to bring about a closer integration of crop and livestock production; to raise the supply and quality of supplementary feeds; to achieve genetic improvements from conventional breeding and modern biotechnical tools; and to complement these gains by cheaper and more effective animal health measures. There is much in the technological pipeline to meet these challenges, which could have their impact well before 2010.
CIAT, for example, has selected forage legumes, grasses and browse species, which fit well into pasture management and ley systems for poor acid soils. Farmers are achieving major increases in stocking rates, and animal weight gains of 100 percent or more. In Latin America, only a relatively small proportion of the total area which could benefit from such improvements has been reached, but a much wider uptake could be achieved by 2010. The technology could also be adapted for the large land areas in Africa and Asia suffering from similar constraints.
Closer integration of crop and livestock systems is partly culture dependent, partly resource-constraint driven, and partly market driven. Land pressures are forcing nomadic pastoralists to settle and become cultivators. Land and labour pressures are forcing cultivators to adopt animal traction, and to keep livestock as a vital source of manure for maintaining or increasing crop production and cash incomes (Mortimore, 1992). Market opportunities and the desire to obtain more regular income streams are favouring dairy-based mixed systems. All of these are ongoing shifts that can be expected to strengthen during the projection period and increase sustainability.
In recent decades, conventional animal breeding has allowed the developed countries to raise productivity per animal by 1 to 2 percent per year. Similar attempts in the developing countries have been far less successful, in part because of unsuitable breeding stock, poor feed and environmentally stressful conditions, particularly temperature stress. Modern biotechnical tools now provide the possibility of modifying the genome of indigenous animals and mixed breeds to cope better with such stresses or diseases, and raise milk and meat output. Moreover this potential can now be brought to the farmer more quickly through new reproduction techniques, like embryo transfer and in vitro fertilization which can speed up the breeding and stock multiplication process. The techniques, however, are unlikely to be widely used in most developing countries by 2010, because of institutional and structural constraints.
Biotechnical tools and processes are also starting to have a practical impact in the animal health sphere, notably in the prevention, diagnosis and control of animal diseases, particularly vector-borne diseases. They will have an increasing impact over the projection period, with growing relevance to the needs of small-scale farmers. New vaccines are already on the market for the control of bacteria causing diarrhoea in lambs, calves and pigs.
In the medium term, vaccines should become available to control trypanosomiasis and theileriosis although commercialization of the former is unlikely to happen soon. Once achieved, however, it would help to free large areas of Africa of trypanosomiasis and replace trypanocidal drugs, new types of which have not been developed for some 30 years with as a consequence an increasing threat of resistant trypanosomes. In the shorter term, new control techniques, such as low level or selective insecticide spraying, pheromone traps and sterile male release, will continue to reduce populations of the trypanosomiasis vector (the tsetse fly) and replace the older but environmentally damaging techniques of massive spraying of residual insecticides, bush clearance and wildlife control. The eradication of rinderpest also could be achieved by 2010 if sufficient resources were to be devoted to this task.
In future research on animal nutrition appropriate to the conditions of the majority of developing countries, greater advantage should be taken of the particular digestive characteristics and complementarily of the different species of livestock. Ruminants can use fibrous feed and non-protein nitrogen sources which cannot be used by monogastric animals, which convert high energy feeds more efficiently. Ruminants can be regarded as two subsystems: the rumen and its microbial contents; and the animal itself which can convert nutrients produced by the microbes and those derived directly from feeds (undegraded nutrients) that usually cost more. Therefore, greater attention is now paid to improving the rumen function through manipulation of its microbial environment. A further point is that supplements of small quantities of essential nutrients to balance those absorbed from the basal diet (generally pasture and crop residues), may greatly increase productivity.
The improved understanding of the feeding process leads to two priority areas of work to enhance livestock performance: optimize protein/energy ratio in nutrients absorbed by ruminants from diets based on poor quality forage; and optimize the digestibility of the basal feed resource. Pursuing these approaches involves research in the area of rumen manipulation, development of local sources of undegradable protein supplements, feed processing to improve the digestibility of low quality forage, and genetic manipulation of plants so that their proteins resist rumen microbial attack.
Examples of innovations embodying these new approaches in animal nutrition which are likely to be increasingly applied in the future are the following. First, the use of locally manufactured multinutrient blocks (molasses-urea) which now have been successfully tested in about 60 developing countries, including India (particularly in milk production) and the Sahel in Africa. These blocks encourage an efficient rumen ecosystem by providing a source of minerals, vitamins and fermentable nitrogen in order to correct an unbalanced nutrient supply. Secondly, leguminous forages as strategic feed supplements for ruminants. Promising species of such legumes are Leucaena leucocephala and Gliricida septum which contribute fermentable nitrogen in the rumen as well as undegradable proteins to diets based on fibrous crop residues. The third example is the fractionalization of sugarcane for pig and ruminant feeding in Latin America. With this method, which could be a breakthrough for feeding monogastrics in the humid tropics, sugarcane juice is the basis of the diet for pigs and can totally substitute for maize. In a fully integrated system, the sugarcane tops and leaves as well as the bagasse are fed to ruminants, with the leftovers being used for fuel. Sugarcane also can be grown in association with soybeans and selected species of fodder trees to provide protein-rich livestock feed.
Developing the potential of biotechnology
Biotechnology is defined as any technique that uses living organisms to make or modify a product, to improve plants or animals, or to develop microorganisms for specific uses. Biotechnology is not new and many products are the result of a simple but effective use of traditional biotechnologies, such as fermentation processes for the production of cassava-based foods, which combined with boiling lowers the cyanide content. Biotechnology here refers to both traditional and modern biotechnology which is based on the use of new tissue culture methods and recombinant DNA (rDNA) technology, often referred to as "genetic engineering". Tissue culture includes in vitro fertilization and embryo culture, protoplasts and the culture of isolated cells and microspores. Such methods are used to produce pathogen-free plants and for germplasm storage. The current largest use of plant biotechnology is in the clonal propagation of plants, particularly of ornamentals because of their relatively high market value. The modern technique of rDNA offers the potential of moving any cloned gene from any organism into any other organism (the transgenic host) and is much more precise and faster in achieving results as compared to conventional plant or animal breeding techniques. However, biotechnology is not a substitute for the latter and should be seen as complementary. Indeed, the strengthening of traditional biological research is an essential prerequisite for establishing a biotechnological research capability in most developing countries.
Biotechnology offers a range of applications mainly for plant and animal production. Some are likely to have an increasing impact well before 2010 while others are of a longer term nature. The former include tissue culture of virus-free stocks of cassava and other root crops, and the introduction of microbial plant growth promoters such as mycorrhiza. The latter include cereals with the ability to fix some of their own nitrogen needs, and transgenic tree crops, but the greatest expectations are in introducing disease- and drought-resistant genes.
Many of these applications will contribute to more sustainable resource use, particularly by (a) gradually raising crop yields and reducing land requirements for a given level of production, thereby lowering the pressures on marginal lands and natural forests; (b) complementing industrial with biological sources of nitrogen for plant growth; (c) raising production performance of plants and animals through growth manipulations and by producing improved vaccines and enhancing disease resistance; and (d) lowering chemical inputs needed per unit of production.