Potato Grower

56 POTATO GROWER | FEBRUARY 2019 PIVOT POINT TO END GUN ASK YOUR NELSON DEALER ABOUT THE BIG GUN® REBUILD PROGRAM NELSON IRRIGATION CORPORATION OFFERS A FULL RANGE OF WATER APPLICATION SOLUTIONS FOR MECHANIZED IRRIGATION. FROM CONTROL VALVES TO PIVOT SPRINKLERS, AND PRESSURE REGULATORS TO END GUNS — THE PACKAGE IS COMPLETE. TEL: +1 509.525.7660 — NELSONIRRIGATION.COM CROP SPECIFIC SOLUTIONS GIVE OUR 3030 SERIES A WHIRL: Press, Spin, Click for On, Off, Flush, Line Flush Functions 1957-7NelsonIrrigation12h.indd 1 5/9/18 4:22 PM increment was multiplied by the average price for biomass in the county (the sum of all crop production in tons of total above- ground biomass produced, divided by total revenue from all crops). For this table, counties in each state were summed to obtain the total value by state for the year. FINDINGS As the table shows, Nebraska benefited most from water withdrawn for irrigation, with Kansas and Texas a distant second and third. Nebraska's estimated IR elasticity of 0.525 for 2007, applied against a yield of 4.856 tons of bone-dry biomass, implies that irrigation was responsible for an extra 2.55 tons per acre. At an average price of $103.50 per ton, this implies that the average acre irrigated across Nebraska realized $264 per acre of additional production, or about $2 billion given the 7.6 million acres irrigated. The geographical distribution of county-level estimates of the value of extra production due to irrigation in the year studied is obvious. The differences between counties are due in part to differences in estimated irrigation elasticity, in part to differences in yields on comparable non-irrigated land, and in part due to differences in the value of the extra biomass produced (the mix of crops differs considerably across the HPA). The analysis also provided an estimate of the crop production damage caused by extreme temperatures (those above 91.4 degrees). For each county and year, the number of hours over the growing season that the crop was exposed to this high temperature was calculated. The result was divided by 24 to convert it to "degree days." Results indicated that each such degree day reduced yields by 3 percent. The average number of such degree days across the entire region and period was 2.7, indicating that on average, extremely high temperatures decreased crop yields by about 8 percent. In Nebraska, the average number of extremely hot days was only 1.4, for a 4 percent loss, but in 2002, there were 2.8 such degree days, causing a loss of about 8 percent of all agricultural production (USDA surveys showed yields to be about 10 percent below trend that year). CONCLUSIONS The Great Plains states, especially Nebraska, depend heavily on the contributions of water from the HPA to augment agricultural production. Nebraska overlies 36 percent of the total HPA area and 69 percent of the total water volume. Water pumped for irrigation in Nebraska contributed about $2 billion worth of agricultural biomass in 2007 alone. While water level changes have been fairly stable over the past 10 years under most of Nebraska's portion of the HPA, this study highlights the economic importance of continued aquifer monitoring and management efforts by various state agencies. Richard Perrin and Lilyan Fulginiti are professors of agricultural economics and policy at the University of Nebraska-Lincoln. Federico Garcia is an agriculture professor at Uruguay's University of the Republic.

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