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Show season. Such a drought in the Northeast in the summer of 1948 is estimated to have cost farm- ers many millions of dollars. In other words, such supplemental irrigation in the East is de- signed to make up for poor distribution of rain- fall where certain crops, especially vegetables, need 1 inch of rainfall each 7 to 10 days for maximum growth. A review of current research going forward in this field indicates that experiments with sup- plemental irrigation have been proceeding with the production of potatoes, pasture, and blue- berries in Maine; pasture in New Hampshire; onions, potatoes, late cabbage, and hay in Massa- chusetts; tobacco in Connecticut; potatoes and clover in Rhode Island; vegetables, Concord grapes, and potatoes in New York; pasture and vegetables in Pennsylvania; truck crops, rotated crops including wheat and potatoes, and sweet corn and clover in New Jersey; tobacco and or- chards in Maryland; truck crops, field crops, and pasture in Virginia; tobacco and pasture in North Carolina; various crops including corn and tobacco in South Carolina; tobacco, pe- cans, and pasture in Georgia; vegetable crops and citrus fruit in Florida; corn in Alabama; and potatoes in Wisconsin. This listing does not in- clude all the humid States using supplemental irrigation, but affords a general view of the nature of the experimentation in this field. Large increases in yields have been experi- enced, although in times of normal rainfall, irri- gated land showed no particular gain in yield over nonirrigated land. The economic justifica- tion of such irrigation in the East is still to be determined. Considerably more experimenta- tion will be needed on this point. In general, the Bureau of Agricultural Economics indicates that the cost of supplemental irrigation is rather high, and the margin of profit likely to be low. A num- ber of technical problems also remain to be solved. Although irrigation in the East has been an individual matter, the Bureau suggests that we may see some relatively large developments as part of multiple-purpose projects for large river basins in the future. It points to the fact that Congress has authorized the Army engineers to construct a project for flood control and other purposes for the Grand Prairie region and Bayou Meto basin, Arkansas, a relatively large supple- mental irrigation development providing im- proved water supply for a rice area. As yet not enough is known about the prob- lems involved in supplemental irrigation to reckon its contribution to the expansion in pro- duction which will be required from existing lands. More research is needed in agronomy, engineering, and economics to furnish answers as to probable effects. There are also questions to be answered as to the nutritional qualities of crops produced with unlimited water as compared with those grown under normal conditions. In gen- eral, it appears probable that the greatest appli- cation of supplemental irrigation will be to the growing of specialty crops, which at this time probably do not require Federal assistance. Production Potentials The agricultural production potentials as de- termined in the preceding sections for the various types of development are summarized and ex- pressed in table 10 in the form of average crop- TABLE 10.-Agricultural production potentials i Expressed in millions of acres of average cropland equivalent. * Based on the assumption that the present rate of drainage and land clearing development would be expanded as a result of Federal activity. * Based on a cropland equivalent acreage of 542 million less 40 million acres for land to be removed permanently from the cropland base, and productivity indexes of 110 and 118 compared to average production for the 5-year period 1945 to 1949. The index of 118 is equivalent to 150 for the 5-year period 1935 to 1939. Ultimate improvement in technology is not estimated. Source: Unpublished data and calculations from the U. S. Department of Agriculture. 165 Considered susceptible of development1 Tvpfi of potential By 1975 Ultimate Irrigation.....-------......................... 9.0 25.0 Flood protection____......._____________ 3.5 4.3 Flood protection, drainage, and land clearing-. 3.8 14.6 Drainage and land clearing.................... J11.2 16.4 Land clearing................................. 2.0 8.0 Subtotal................................ 29.5 68.3 Improved technology: * Moderate increase-..........._________ 46.0 _________ Substantial increase_________.......... 77.0 ............ |