Comparison of Center Pivot Low Elevation Spray and Low Energy Precision Application of Irrigation on Cotton in the Texas Southern High Plains

The Ogallala aquifer has been declining in most areas of the Texas Southern High Plains and has reached critical drawdown levels in many.  According to the 2000 Texas Water Development Board survey center pivot systems were the primary source of delivering irrigation water covering 3 million acres in the Texas High Plains and therefore offer the greatest potential for future water savings.  The efficient use of irrigation resources is vital to the survival of area producers, so in September of 2004 the project “An Integrated Approach to Water Conservation for Agriculture in the Texas Southern High Plains” was approved by the Texas Water Development Board.  This multidisciplinary and multi-entity demonstration project is run by a producer board, elected by producers in Hale and Floyd Counties with the purpose of encouraging research, demonstration, and implementation of practices to reduce water use while ensuring economic viability.  The Texas A&M AgriLife Extension Service FARM Assistance program has collected income, expense, yield, and water use information from the demonstration sites each year from 2005 through 2012.  During the exceptional drought of 2011 and ongoing drought of 2012 an observational project was conducted on a Hale county cotton farm to determine the benefit of operating a center pivot irrigation system in the low elevation spray mode (LESA) versus low energy precision application mode (LEPA).  LEPA systems are considered to have a 5% higher application efficiency rate than LESA systems.  Therefore, the project sought to discover if the increase in efficiency would lead to higher water use efficiency and greater profitability.  This was accomplished by running two of nine spans in LESA mode with the other seven spans in LEPA mode.   The project demonstrated both higher water use efficiency and greater profitability for cotton irrigated with a LEPA system in both 2011 and 2012.