Land and water resource planning using goal programming

Abstract

Crop planting scenario 1 632Regional results 633 County results 636 Summary 637Crop planting scenario 2 638Regional results County resultsCrop planting scenario 3 Regional results County resultsCrop planting scenario 4 Regional results 645 County resultsCrop planting scenario 5 Regional results County results 650Crop planting scenario 6 Regional results County resultsCrop planting scenario 7 Regional resultsCounty results Summary 65 Regional results County resultsCrop Planting Scenarios without Erosion Control 662Regional results 662 County results viii Effect of Using Gibson's Increased Future Yields 671 Crop planting scenario la 671 Regional results 671 County results 673 Crop planting scenario 2a 673 Regional results 673 County results 673 Crop planting scenario 3a 675 Regional results 675 County results

Economic feasibility studies of irrigation in Northwest Iowa

“…Principal soil association areas in Northwest Iowa (43) compared to other parts of the state , This moisture available for plant uses is in soil from 0 to 5 feet from the surface. The upper limit of water usuable by plants is called "field capacity" and the lower limit is called "the wilting point," It is assumed that "very low" is less than three inches, "low" is 3 to 5 inches, "medium" is 6 to 9 inches and "high" is more than 9 inches of plant available water in the top five feet of soil (43), Tables 5 and 6 show the average plant available water and soil moisture of 12 counties in the region (51). The average values of 10,4 inches of available water and 6 .…”

“…Table 4. Mean, minimum and maximum annual precipitation at various locations in Northwest Iowa, inches (44) 1 inch -16 miles Figure 6 . Average seasonal snowfall in Northwest Iowa, i nches (50) Well depth varies from lS to 20 feet to as much as 400 feet.…”

“…In order to eliminate significant reductions in optimum yields due to water constraints , the model assumes t hat the soil moisture has to be maintained at the minimum level of 6.5 inches during June and 7.3 inches during July and August. From September 1 until harvest ther e is again enough water supply from irrigation to meet evapotranspiration for corn plants such that irrigation is not needed (43).…”

“…Therefore, the effective rainfall lev el is approximated by the precipitation in Table 22. (44). This can be summarized by the following equation : where WATij = total inches of water applied by irrigation system j in month i proportionally from the maximum level as shown in Table 26 for different techniques of production.…”

“…Rainfall was over three inches above normal for the year, but the yield was the lowest on record, i.e. , 50 bu of corn per acre (Rossmiller,43,. Supplemental irrigation is used to ensure that enough soil moisture is available prior to planting, during critical stages of plant growth (tasseling, silking, pollination) and to reduce stress due to high temperatures and low humidity.…”