Limited and full irrigation comparison for corn and grain sorghum

The current high cost of irrigation pumping and areas of declining well capacities in the Southern High Plains Groundwater District in Southeastern Colorado, prompt a review of irrigation practices in this region. The importance of limited irrigation (supplemental irrigation) has traditionally been associated with very low capacity irrigation wells. The current high fuel prices and associated pumping costs, combined with the low commodity prices, places new emphasis on limited irrigation as a replacement for full irrigation. We define limited irrigation on corn and grain sorghum as applying one in-season furrow irrigation of less than 9 A-in./A or a similar amount of water applied with a sprinkler. Applying less than 9 A-in./A as an in-season irrigation assumes that the soil water profile is full from sufficient winter moisture, or, if winter moisture is lacking, the soil water profile is filled by preirrigation. An extensive study by McLaughlin Water Engineers (Anderson and Edwards, 2001) of the aquifers for the Southern High Plains Groundwater District in Southeastern Colorado revealed that fully two-thirds of the irrigation wells in the district have an average expected life span of 50 years at the current extraction rates. This, of course, means that the pumping capacity of affected wells will continue to taper off until the wells are no longer economical to pump. As more and more wells become smaller capacity irrigation wells, economics will favor limited irrigation compared to full irrigation.