Evaluation of a barley-soybean double-cropping system

The expanding population of the world has an ever increasing food requirement and the development of methods to increase production are needed in developed countries as well as in underdeveloped countries. For example, soybeans are a major source of protein, fats, and oils and production has expanded in recent years to meet the increased demand throughout the world. Many producers are increasing their production and profits by producing two crops each year from the same production area (double-cropping). In the United States soybeans planted after the harvest of small grains is an example of double-cropping which has increased annual income in many soybean producing regions. Revelle (1966) stated that increased cropping intensity by double-cropping would increase food production in underdeveloped countries such as India and thus establish a better balance between population and food supply. In the southeastern United States double-cropping soybeans after small grains has been practiced for many years, but only recently has become important in Tennessee. In a double-cropping system soybeans must be planted later than desirable for high production. Yields may be reduced because soil moisture may be limiting for stand establishment and the growing period is reduced. Soybean varieties are sensitive to daylength and varieties suitable for single cropping may not be desirable for the late planting time required for double-cropping. Similarly, small grain varieties differ widely in time of maturity and therefore, may differ in their desirability for use in a double-cropping system. Thus, information is needed on production and management techniques using double-cropping systems. Parks, Bell, and McCutchen (1965) indicated profitable returns from a wheat-soybean double-cropping system in Tennessee. The present study was conducted (1) to evaluate the feasibility of a barley-soybean double-cropping system; (2) establish objectives for breeding barley and soybean varieties for double-cropping; and (3) to establish points of departure for additional research on double-cropping.