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<br />The most important data for this research study was the annual depth of irrigation applied by each of <br />the 80 participants. The following steps were used to determine/calculate those values: <br /> <br />I. The base indoor water use was calculated, in gallons per c'apita per day, with the input of the <br />water use for the approximate period of December I, 1993 to March 1, 1994, and the number of <br />residents. This value was adjusted, as necessary, with the information provided by the <br />participant questionnaires: <br /> <br />2. The total water use was calculated for the approximate period of March 15, 1994 to November <br />15, 1994, to include the entire lawn watering season. <br /> <br />3. The indoor water use for the same period of time was estimated/calculated by starting with the <br />base indoor water use previously determined, and adjusting as necessary with the information <br />provided by the participant questionnaires. <br /> <br />4. The volume of water used on the landscape was calculated by subtracting the <br />estimated/calculated indoor water use from the total water use for the time period. <br /> <br />5. Finally, the annual irrigation depth was calculated by dividing the volume of landscape water by <br />the total irrigated area. <br /> <br />RESULTS <br /> <br />The average annual depth of irrigation was found to significantly differ between the two groups, with <br />the difference being the reverse from what would have most likely been hypothesized. The Group I <br />participants, who did not amend their soils with composted manure, were found to apply an average <br />annual irrigation depth of 31.8 inches. The Group 2 participants, who did amend their soil and <br />would have been the most probable group of the two to use less water, actually used 25% more <br />water; an average application depth of 39.9 inches. Attachments F and G provide more detail on the <br />annual irrigation depths for the two groups. The "Interpretation and Conclusions" section below <br />includes possible explanations for this unexpected result. <br /> <br />The Kentucky bluegrass irrigation requirement for the 1994 watering season in Fort Collins, using the <br />modified Penman equation and a factor of 0.6 for effective precipitation, was 24.1 inches. Therefore, <br />both groups over-irrigated; Group 1 by 32 % and Group 2 by 66%. <br /> <br />Additional data was analyzed for the purpose of assessing other (in addition to amended versus <br />unamended) variables that might have affected these results. Following is a listing of those variables, <br />and the associated analysis: <br /> <br />Location -- the specific location of the home, within the city, could relate to two factors in <br />landscape water use. The first factor is the soil type, which can vary somewhat from one <br />portion of the city to another. Varying soil types can affect the amount of water required for a <br />given landscape. The second factor relates to the extent of mature trees, which is greater in the <br />older part of town. The greater the extent of trees, and therefore shade, the lower the water <br /> <br />4 <br />