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<br />M <br />~ <br />(tJ <br />C' <br /> <br />. <br /> <br />. <br /> <br />In the past, some producers have indicated that data provided to them <br />did not show the actual moisture conditions of the field. They felt <br />that more soi I moisture deficit was being shown than necessari Iy true; <br />especially after cutting when alfalfa plants do not use as much water. <br />One producer with newly seeded alfalfa field said that although our <br />data showed deficit in his field he did not believe this to be the <br />case. He was of the opinion that the roots of first year alfalfa go <br />down to only 4 feet rather than 6 feet. <br /> <br />Of the 9 alfalfa sites, 5 of them had deep percolation in excess of <br />the acceptable deep percolation (Table 4) needed for leaching. Sites <br />33, 35 and 36 with siderol I sprinkler systems did not have any deep <br />percolation. <br /> <br />Corn: Only 2 sites were monitored In 1989. Both sites, 26 and 27 <br />had different crops in 1988, fall grain and alfalfa respectively. <br />Total acreage monitored was 36 acres, or less than 0.2% of the 21,400 <br />acres in the Grand Valley <Table 7>. <br /> <br />The average deep percolation for the 2 sites monitored was 29.0 inches <br /><Table 8) which is over 200% of the average deep percolation for all <br />sites mon i tored (12.3 inches). The amount is excess i ve I y over the <br />amount requ i red to contro I sa I t movement (Tab I e 4). However, the deep <br />percolation for the 2 sites may be actually lower than indicated <br />because of the way deep percolation is currently estimated for annual <br />crops; also the ET values for corn seem to be low due to built in <br />stress related factors in the formula. Site 27 was cut for si lage and <br />this also accounted for low corn ET for 1989. These deficiencies wi I I <br />be looked at in the com i ng year and correct ions wi I I be made to a I I <br />previously reported data. <br /> <br />Towards the middle of the season, individual irrigation summaries, <br />soil moisture deficit data, and daily ET data were provided to the <br />farmers following each irrigation event. <br /> <br />Irrigation efficiencies at both corn sites were poor although site 26 <br />was better in 1989. Site 27 had alfalfa in 1988 and efficiency was <br />over 50%, also deep percolation was half of 1989. One reason for this <br />increased deep percolation and low efficiency could be attributed to <br />change in farm operator. At this site, 60% of deep percolation <br />occurred by the end of the second i rri gat i on <Tab I e 8>. Si te 26 had <br />deep percolation only during the first irrigation. The later <br />irrigations did not meet plant water requirements (Appendix A). The <br />so i I prof i I e was never comp I ete I y fill ed and the crop may have been <br />stressed to some extent, although there were no visible signs of <br />stress. <br /> <br />The average deep percolation and percentage distribution by irrigation <br />events for the 2 corn sites are provided on Table 8. <br /> <br />19 <br />