Issue link: http://read.uberflip.com/i/1073364
Determining irrigation's dollar value to agriculture Water Value Diggin' In Diggin' In Recent research has shown that the extra agricultural production from irrigation across the High Plains Aquifer (HPA) was worth about $3.5 billion in 2007, $2 billion of which was produced in Nebraska. Obviously, the aquifer water is valuable. The HPA underlies an area that includes southern South Dakota, southeastern Wyoming, eastern Colorado, Nebraska, western Kansas, eastern New Mexico, northwestern Oklahoma and northwestern Texas. This region has a semiarid climate that makes crop production highly dependent on irrigation. Given that irrigation has resulted in severe depletion in some areas of the HPA, it is important for policy purposes to identify the overall value of this resource in agricultural production. ANALYSIS The research analyzed crop production and weather information each year from 1960 to 2007 for each of the 205 counties overlying the HPA. The key parameter was the ratio of yields (total biomass per acre) on irrigated land compared to non- irrigated land (the "IR elasticity"). IR elasticity averaged about 50 percent over the whole period but had increased to about 60 percent by 2007. Estimates of IR elasticity were obtained using a regression technique that related observed county dry matter yields to the share of irrigated county area, the rate of fertilizer and chemical applications, and weather variables. The latter consisted of growing season precipitation and four "degree day" variables measuring the amount of time over the season that the crop was exposed to various temperature ranges: 23 to 46, 46 to 59, 59 to 91, and 92 degrees Fahrenheit or over. The table shown here illustrates how the estimated IR elasticity was converted into total value of production, summed across counties to state levels. First, observed yields at the county level were multiplied by the IR elasticity estimate for the county to estimate the extra production due to irrigation. Next, that yield IRRIGATION | By Richard Perrin, Lilyan Fulginiti & Federico Garcia 54 POTATO GROWER | FEBRUARY 2019