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<br />'. <br /> <br />L"" <br />I.") <br />~-l <br />...-4 <br /> <br />(,,~-' <br /> <br />upon visual inspection of the field; great amounts of residue left from the previous <br />crop of corn in the furrows created a very rough furrow structure which should <br />have led to impeded flows and less runoff. A possible explanation to this <br />phenomenon is that no tillage was performed on this side of the field; rather. the <br />original furrows and beds were simply re-shaped, Some packing of the surface soil <br />may have occurred during the re-shaping process which may have reduced <br />infiltration of the irrigation water. <br /> <br />The fact that surge irrigation negated the effect of tillage or no tillage on infiltration <br />and runoff amounts is also of interest. This result has significant implications <br />regarding future procedures of crop residue handling and surface irrigation and <br />should be studied in detail. Surge irrigation may offer a significant advantage <br />when conservation tillage procedures are applied to a surface irrigated field. <br /> <br />The forty percent reduction in water use obtained by surge irrigation as compared <br />to conventional irrigation on the field is of great significance. Explanations for this <br />occurrence have been elicited elsewhere. <br /> <br />Several reasons may exist for the apparent large negative deep percolation values. <br />This field site is located about 8.5 miles from the weather station that was used to <br />generate the evapotranspiration data used to estimate soil moisture deficits. There <br />is the possibility of a micro-climate change between the two sites. ET estimates <br />as used in the Grand Valley may be higher than needed. A water table condition <br />may exist on this site which would modify the ET estimates for the field. <br /> <br />FOLLOWUP: <br /> <br />Attempts were made to contact each surge unit recipient to determine their <br />acceptance of the surge concept. A questionnaire was used to document the <br />responses. A copy is included. Responses are summarized as follows: <br /> <br />Acres in surge sets ranged from 2 to 8. while conventional. companion sets ranged <br />from 0.5 to 6.4 acres. <br /> <br />Time to start a conventional set ranged from 0.5 minutes to 120 minutes with <br />surge start time ranging from 1 to 120 minutes. <br /> <br />The various crops listed include: alfalfa. corn small grains, orchard, and pastures. <br /> <br />The fertigation concept is most useful on annual grass crops such as corn and 11 <br />% of the farmers used this method. <br /> <br />Yield differences were not noticed by the cooperating farmers, <br /> <br />Fields were probed by 76% of the farmers during irrigation events. <br /> <br />6 <br />