losses, as well as for improvements in quality. They
will also play a role in programing resource inputs into
crop production and maximizing yields.
 Sensors related to mechanization include those that
 will monitor or sense water stress of plants, soil
 moisture turgor pressure, color, temperature, heat
 absorption, firmness and leaf area index. Data from
 these sensors will be used to minimize the effects of
 both biological and environmental stresses during
 cultural and harvest operations. Combines and grain
 harvester sensors will monitor slickness and hardness of
 straw. Sensors on tillage equipment will adjust applica-
 tions of materials to soil conditions and by soil types.
 The future will see sensors that will measure critical
 parameters related to crop production and quality.
 The need for labor-, land-, water- and fertilizer-
 saving technology from agricultural engineering
 research will depend on the price relative to capital.
 Price will be important as an indispensable dimension
 in engineering design. An uneconomic design is a
 wrong design.
 The need for labor-saving technology has increased
 over the past century as wage rates have increased.
 Though agricultural engineers have been criticized for
 allegedly driving labor off farms with labor-saving
 technology, it has more often been a case of finding or
 inventing machines to replace the labor that was leav-
 ing or becoming much more costly, than of premature-
 ly driving labor out of agriculture.

 As farm and non-farm wage rates increase with
levels of living in the next 50 years, the two alternatives
to more labor-saving technology will be either higher
food prices or regulations to force laborers to stay in
agriculture as disadvantaged peasants. Such alter-
natives introduce both economic and social dimensions
into agricultural engineering research. These must be
addressed by agricultural engineers themselves or
engineers in collaboration with rural sociologists, agri-
cultural economists and humanists (Martin, 1983).
 Conservation tillage (ridge and living mulch types)
will increase in importance. Conservation tillage,
along with minimum tillage, no-till, double cropping,
contour farming, green chopping, rotational grazing,
residue management, terraces, use of chisel plowing,
intercropping and related mechanical practices, will
require more SM research by agricultural engineers
working closely with hydrologists, economists, farm
management scholars, agronomists, animal scientists,
soil chemists and electronic physicists. Improved con-
servation practices are needed for land now farmed
and grazed, as well as for the additional, more fragile
soils to be farmed in the next 50 years.
 Machinery inputs and fuel consumption per unit of


work may be reduced to one-half of current require-
ments with the development of better and more effi-
cient engines. Spacing and other modifications in
planting and cultural practices will facilitate more in-
tensive cultivation, more double cropping and addi-
tional investments in the productive capacity of soils.
Machinery may be smaller and more efficient, espe-
cially for part-time operators of small-scale agri-
cultural enterprises.
 Natural Resources Physical management of
 privately owned natural resources will be an important
 SM research area for agricultural engineers. Research
 must continue on irrigation, drainage, climate and
 weather, conservation tillage and waste management.
 Supplemental irrigation will be a means of increasing
 both the stability and magnitude of crop production in
 what traditionally have been rain-fed areas. Irrigation
 could increase yields by 50 percent on good agri-
 cultural lands in temperate zones. Use of drip irriga-
 tion for high-value crops will continue to expand, en-
 couraged by scarcer, more expensive water and labor.
 Delivery systems will be designed for efficient use of
 fertilizer and pesticides, as well as water. Drip
 irrigation will be extended to sugarcane, cotton,
 sorghum, corn and peanuts.
 Drainage is as important as irrigation for water and
 land management. Plastic drain tubes are replacing
 clay tiles. They are lightweight, flexible and easy to
 transport, and they have low labor and energy costs.
 Though durability has yet to be established, they are
 expected to last for decades. Another new development
 is the drain plow, for placing the plastic tubes in
 narrow trenches. Power is supplied by tractors of 250
 horsepower or more. There are both track and wheel
 types. The wheel type has flotation tires. Additional
 SM research on drainage is needed to attain further
 such improvements.
 Climate modeling, resource assessments and meteor-
ology will continue as important research areas for
agricultural engineers in most institutions. Remarkable
progress has occurred in thematic mapping and multi-
spectral imagery. It is now possible with current in-
strumentation to inventory accurately changes in land
cover, cropping patterns, water and energy availabili-
ty and biogeochemical cycles-to inventory, in fact, all
life-support systems that affect food production and
future biological productivity (Wittwer, 1983a).
Remote sensing and observations from satellites will
become increasingly important for monitoring changes
in resource inputs into food systems and for long-term
weather forecasting. The development of predictive
models of natural and man-made physical, chemical
and biological changes related to the production of
food and other renewable resources will be significant.
The National Aeronautics and Space Administration is