74 THE FIVE-YEAR OUTLOOK 



contrast, the production of food consumes only about 3 

 percent of the total energy used) (AAAS-8; ASTR-llI). 

 The issues of general water resource availability and water 

 quality preservation are discussed in the Natural Re- 

 sources and the Environment sections of this chapter, 

 respectively; however, some points should be reiterated 

 here. 



Water as a resource is extremely variable in its distribu- 

 tion and almost impossible to transfer economically over 

 large distances. Moreover, water is a particularly 

 unpredictable resource. In much of the world, rainfall is 

 never "normal," but varies greatly from year to year 

 Thus, a large burden on the agricultural system is to 

 overcome some of the ups and downs in water availability, 

 and the traditional approach has been to move water from 

 place to place, such as in irrigation. That technique, 

 however, can be very labor intensive, it consumes energy, 

 and it can reduce both the quality and the quantity of water 

 resources downstream. Therefore, water movement is a 

 less than optimal solution to water shortage problems. 



Several research directions are being followed in an 

 attempt to provide alternative mechanisms for dealing 

 with the water constraint on agricultural productivity. For 

 example, new developments in irrigation, particularly in 

 improving the efficient use of water through such tech- 

 niques as drip irrigation, timing improvements, and use of 

 such alternate energy sources as the sun and wmd to power 

 irrigation systems have much promise. Research is also 

 being pursued in improving the efficiency of desalination 

 and developing plant species that can be grown in high- 

 saline water, thus expanding the potential for the use of 

 increasingly brackish water supplies and direct use of sea 

 water. Considerable progress in those areas is expected 

 over the next 5 years (AGR). 



PROVIDING ADEQUATE AMOUNTS OF NUTRIENTS FOR 

 CROP GROWTH 



The problem of nutrient supplies for agriculture, both 

 through natural and synthetic fertilizers, is particularly 

 critical, not only in this country but in many developing 

 countries. The move of agriculture from prime land to less 

 desirable land, as noted earlier, requires supplementing 

 nutrient levels to compensate for the reduced levels of 

 natural supplies in the less-than-desirable land. But the 

 production of artificial fertilizers is also subject to trade- 

 offs. The primary source of nitrogen used in the United 

 States to produce fertilizer is natural gas. As energy prices 

 rise further, so will agricultural production costs. More- 

 over, the long-term effects of intensive reliance on syn- 

 thetic fertilizers are unknown, particularly in the poor 

 soils reclaimed from tropical forests for agricultural use 

 (NRC-5; ASTR-HI). 



Scientific and technological advances can have signifi- 

 cant impacts on the problems of providing adequate nu- 

 trients to support plant growth. Research is proceeding on 



several levels. On what has been called the macro level, 

 experiments with multiple cropping, recycling of agri- 

 cultural waste products, organic farming, and other 

 changes in cultivation practices have shown some success 

 (AGR: ASTR-IU). 



On the micro level, research in nutrient cycles is in 

 progress. When ecosystems are disturbed, so too are the 

 balances among nutrients that are shared throughout the 

 food chain. Plants vary significantly in the relative effi- 

 ciency of their nutrient intake processes, and an under- 

 standing of the factors that make for greater efficiency in 

 nutrient uptake is just starting to emerge. That kind of 

 research provides an opportunity for the eventual selec- 

 tive breeding of plants that can absorb and process much 

 greater volumes of nutrients from the same basic source. 

 Ultimately, research into mutually beneficial relationships 

 among plants, such as those that exist between rice and 

 certain types of algae, may improve the efficiency of plant 

 nutrition significantly, thus improving yields without in- 

 creasing the basic nutrient investment required (NRC-5). 

 Those and similar lines of research present major oppor- 

 tunities for advances in supplementing nutrients as natural 

 supplies diminish. 



INCREASING PRODUCT YIELDS 



The existence of current and potentially increasing con- 

 straints on the availability of resources for agriculture is 

 cause for concern about the ability to increase agricultural 

 productivity to the levels required in the future. Making 

 optimal use of available resources is one approach to 

 increasing productivity in the face of the problems. An- 

 other approach is to increase the yield of agricultural 

 products grown under the resource-constrained condi- 

 tions, and that increase can be accomplished in a variety of 

 ways. 



ALTERING PLANT AND ANIMAL STRAINS 



Scientific and technological advances in recent years have 

 opened a range of opportunities for improving crop strains 

 and crop versatility. While selective breeding of agri- 

 culturally useful species is almost as old as human civi- 

 lization, recent developments in molecular, genetic, and 

 developmental biology have improved scientists' ability 

 to understand how plants and animals function and grow. 

 Therefore, there is the potential to engineer more deliber- 

 ately further changes in the characteristics of plants and 

 animals. The opportunity is partly the result of new de- 

 velopments in fundamental knowledge, partly the result 

 of such new manipulation technologies as recombinant 

 DNA and gene splicing. One particularly promising area 

 for development is the creation of plants that can fix 

 nitrogen biologically, either by themselves or with the aid 

 of symbiotic bacteria, instead of relying on chemically 



