Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/15/2006
Publication Date: 11/12/2006
Citation: Angadi, S., Gowda, P., Howell, T.A. 2006. Assessment of sorghum suitability in Ogallala Aquifer region based on heat unit accumulation [abstract]. ASA-CSSA-SSSA Annual Meeting, November 12-16, 2006, Indianapolis, Indiana. 2006 CDROM.
Technical Abstract: Water levels in the Ogallala Aquifer are decreasing at an alarming rate. Excessive pumping of water for irrigation and low recharge rates have been the major causes for the decline. There is a need to select crops that are relatively more water use efficient for sustaining the aquifer. The region is also known for large beef and dairy production. Corn is the major crop that supplies green forage, silage, and grains to the animal industry. Sorghum is a drought tolerant and more water use efficient alternative to corn. However, sorghum is a warm season grass and needs warmer environment compared with corn. An evaluation of sorghum thermal suitability in the aquifer underlain region based on long term weather data is urgently needed. Temperature data (1970-2000) from 232 counties in the Ogallala Aquifer region were used to calculate growing degree days to the base temperature of 10 degrees C (GDD). Four seeding date scenarios from May 1 to June 15 in 15 day increments were used for the calculation. Suitability of three maturity classes of sorghum with GDD requirements of 1525 (late), 1375 (medium) and early (1200) were assessed in each seeding date scenario. Growing season heat accumulation in the study area ranged form 692 to 2652. Based on growing season heat accumulation, about 85% of counties were suitable for growing any maturity class of sorghum. However, delaying the time of seeding imposed restriction on type of sorghum grown and only 60% of counties could grow any type of sorghum if seeded on June 15th. About 3% of all counties could not grow sorghum if time of seeding delayed beyond June 15th. If seeded on May 1st, early maturing sorghum cultivars will help in extending thermal suitability of counties by 14%, which further increased to about 38% under delayed seeding. Exceedance probability analysis was used to assess the risk associated with heat accumulation in Ogallala Aquifer counties.