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Fol lowing the presentation, Dr. Kanemasu reiterated his opinion tha.t large advances can be made in modifying evapotranspirat,ion. In response to a question about the use of evaporation supressants on the soil, he pointed out a developed canopy evaporates approximately 70 percent, whereas the soi 1 evaporat ion accounts for about 30 percent of ,the evap6- transpirational losses. Therefore,. it is desirable to concentrate'efforts on methods to reduce plant losses. With cooperative efforts from plant breeders, crop physiologists, and agrometeorologists. favorable advances can be foreseen. For greater water use efficiency, basic and applied research on both photosynthesis and transpiration is needed. The problem is that if you decrease transpiration by increa~ing Ra + Rs (see equations on page 7), you wiil also decrease photosynthesis which is .j. " . also a function of Ra + Rs. Dr. Kanemasu ,bel ieves that an important step to increasing the ratio of PIT lies in the understanding of the Rm (mosephyll resistance) factor., A decrease in: Rm would increase P but not affect T. He also pointed out that although the plant does not directly use much water, water is e~se~tia) in the tra~sport of nutrients from the soil to the plant and provides evaporative cooling for the photosynthesizing leaves. A question was asked regarding the effect of potassium upon plant structure. Dr. Kanemasu repl ied that the use of potassium usuarly increases the number of and the size of stomata, a~d consequently more water is used. Evans Banbury commented on changes in management and technology which may reduce the projection of withdrawal of underground water in Kansas by the year 2000. They are included in this memorandum as presented. "I am not an expert in future projections but perhaps some of my comments may provoke additional thought. My remarks are confined chiefly to.the section of Northwest Kansas with which I am most familiar and my personal observations on agricultural irrigation deve 1 opment. ., Our future underground water supply has become the concern of many people of the Northwest Kansas area during the past few years. This has been accelerated by the extremely rapid development of deep well' agricultural irrigation. During the late forties and ea~ly fifties, very few expected much increased irrigation in Northwest Kansas--I was one of them--wheat prices were good, wheat yields good, and the area is ~oi~d for its high qual ity wheat production. Irrigation yields .fur <.0.-" and sorghums were less than half our present yiel~s under irrigation. .Thus.from an economic standpoint, it appeared rather remote in the late forties.to expect ~ny' marked increase in irrigation in our section of the state. But as the saying goes--it did in spite.of what .we thought then. . . The increase has been phenomenal. In 1949, there were, to.my knowledge, nine irrigation wells in Sherman County. and only one or two were pumped. In 1965, reports. indicated some 240 wells-- , . 8.