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Cooperative Extension July 23, 1992 For Immediate Release . . . . . . Surge Irrigation Saves WaterSurge irrigation has used 15, 30 and 40 percent less water than conventional irrigation in 1992 on the three corn irrigation demonstration sites under the Patterson Hollow Water Quality Project. "This is a savings of 5.1, 6.9 and 12.9 inches per acre, water that can be used for more timely irrigation of the rest of the corn acreage or on other crops," said Jim Valliant, irrigation specialist for Colorado State University Cooperative Extension in southeast Colorado. The greatest saving of 12.9 inches per acre is on a 1200 foot long field west of Rocky Ford. During the preplant irrigation, the conventional areas used an average of 11.0 inches per acre while the surge irrigated areas used only 5.7 inches per acre. The land was then rod-weeded due to an infestation of shattercane and Johnson grass, Eradicane was incorporated with a Lely Rotera and the land was rebedded and planted. Due to the extremely loose soil conditions and the dry weather during April and early May, the corn had to be irrigated for germination. The surge irrigated area used 4.7 inches per acre with 0.1 inch runoff while the conventional irrigated area required 10.7 inches per acre to get to the end of the field with only 0.5 inch per acre of runoff. These results indicate much of the water being applied was moving through the root zone and being lost to the crop for future use. Water moving beyond the root zone can also carry nutrients and make these nutrients unavailable to the plant. During the next two irrigations at the 7-leaf and 12-leaf stages of growth, surge irrigation used 9.5 inches and conventional irrigation used 11.1 inches per acre, a savings of some 2.6 inches with surge. This brought the total for the four irrigations to 19.9 inches on the surge irrigated areas and 32.8 inches on the conventional irrigated areas. Valliant pointed out, "This amounts to a saving of 40 percent by using surge irrigation." On a 2000 foot field west of Rocky Ford, surge irrigation has reduced the total amount applied 6.9 inches per acre, from 23.2 to 16.3 inches per acre -- a 30 percent saving. Again, the greatest savings came when the ground was loose during the preplant irrigation: The conventional area used 14.5 inches and the surge areas used 7.1 inches. A hot, dry April and early May caused the corn to need an irrigation to insure uniform germination. The corn was also irrigated at the 10-leaf and 12-leaf stages of growth. At the demonstration site west of Manzanola, surge irrigation has saved some 5.1 inches of water when compared to conventional irrigation. On this 1200 foot field with a slope of 1 to 2 percent, the surge irrigation has shown a savings on each of the three irrigations applied to date. At preplant, the surge irrigated areas used 4.8 inches compared to 8.6 inches on the conventional irrigated areas. At the 5-leaf stage, surge irrigation used 1.9 inches compared to 2.3 on conventional and at the 10-leaf stage the surge used 3.0 inches compared to 3.9 inches on the conventional irrigated areas. At each site, rains have helped fill the soil profile in June and July and only the top two feet have needed to be replenished as indicated by gypsum blocks placed in the soil at 1, 2, 3, and 4 feet. With an available water holding capacity of 2.4 inches per foot and the blocks usually indicating an average of above 50 percent available moisture, the soil will only hold about 2.4 inches of water in the top two feet. This would suggest that surge irrigation is supplying the needs of the crop and not going below the root zone while the conventional irrigation has allowed water to be wasted below the root zone. "These demonstration sites will be harvested in the fall and yields will be the main deciding factor when comparing surge and conventional irrigation, but results in 1991 and from other locations indicate surge irrigation is a way to reduce labor and - stretch - your water while producing top yields" Valliant said.
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