A Retrospective Review of Cotton Irrigation Termination in the Midsouth

Arkansas produces the third most cotton and cottonseed of any state in the US and approximately 30% of cotton in the MidSouth.  Irrigation plays an important role in producing consistent and reliable yields in the region.  Of the approximately 4 million acres of irrigated agricultural land in Arkansas, over 11.6% is in cotton.  Most cotton acreage is irrigated from the alluvial aquifer, which is being used at an unsustainable rate resulting in large cones of depression.  Mississippi county has produced the majority of the cotton in the state for the past several decades, accounting for 20-25% of Arkansas production.  Declines in the alluvial aquifer in this county have been slow due to recharge from the Mississippi River.  However, in 2010 new small cones of depression in the alluvial aquifer have been noted in Mississippi County.  A retrospective review of irrigation practices from 2005-2012 from a cotton farm in Mississippi County, Arkansas is presented.  Timing of irrigation termination and total irrigation amounts are presented from both pivot and furrow irrigated fields covering approximately 5,000-7,500 acres each year.  COTMAN, a COTton MANagement system, is used to identify field-specific conditions.  Heat units are calculated with climate data and used in conjunction with COTMAN information to determine adherence or departure from established guidelines for irrigation termination.