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United States Department of Agriculture

Agricultural Research Service

Research Project: IRRIGATION MANAGEMENT AND AUTOMATION FOR INCREASED WATER USE EFFICIENCY

Location: Soil and Water Management Research

Title: Evapotranspiration of corn and forage sorghum for silage

Authors
item Howell, Terry
item Evett, Steven
item Tolk, Judy
item Copeland, Karen
item Colaizzi, Paul
item Gowda, Prasanna

Submitted to: Environmental and Water Resources Institute World Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: January 25, 2005
Publication Date: May 12, 2008
Citation: Howell, T.A., Evett, S.R., Tolk, J.A., Copeland, K.S., Colaizzi, P.D., Gowda, P. 2008. Evapotranspiration of corn and forage sorghum for silage. In: Proceedings of the Environmental and Water Resources Institute World Congress, May 12-16, 2008, Honolulu, Hawaii. 2008 CDROM.

Interpretive Summary: The Southern High Plains has experienced a rapid expansion of dairies. These dairies have a large demand for forages and silage crops. Often corn silage is used, but corn has a large irrigation requirement. Forage sorghum can provide high quality silage with much less irrigation water required, but the yield of forage sorghum will be less than corn. Corn and forage sorghum were grown on precise weighing lysimeters to measure the crop water use in 2006 and 2007 at Bushland, Texas. Both seasons had normal to above normal rainfall although both years had slightly less than normal annual rainfall. The 2006 season was warmer and had a greater water use. The corn in 2006 had to be replanted with a short-maturity hybrid causing a direct species comparison of yields and water use invalid. Seasonal crop water use was 671 mm for forage sorghum with a yield of 1.48 kg/m**2 in 2006 and 489 mm in 2007 with a yield of 1.70 kg/m**2. The water productivity (yield per unit water) was 2.21 kg/m**3 in 2006 and 3.47 kg/m**3 in 2007. Seasonal crop water use was 418 mm for corn for silage with a yield of 1.52 kg/m**2 in 2006 and 671 mm in 2007 with a yield of 2.44 kg/m**2. The corn water productivity was 3.63 kg/m**3 in 2006 and 3.64 kg/m**3 in 2007. Since the species comparison was valid in the 2007 season, forage sorghum achieved comparable water productivity as corn with less crop water use (~73% of corn water use) and irrigation requirement although with a reduced yield (~62% of corn dry matter). Forage sorghum can be a water conserving alternative for high quality silage for dairies in the Southern High Plains.

Technical Abstract: In the U.S. Southern High Plains, dairies have expanded and have increased the regional demand for forage and silage. The objectives were to measure water use and determine crop coefficients for corn (Zea mays L.) and forage sorghum (Sorghum bicolor (L.) Moench) produced for silage on the Southern High Plains. Water use was measured with large, precision weighing lysimeters in 2006 and 2007. Both growing seasons had normal to above normal rainfall. The 2006 season was more advective with greater mean daily reference evapotranspiration (ET) rates. Seasonal ET was 671 mm for forage sorghum with a yield of 1.48 kg/m**2 in 2006 and 489 mm in 2007 with a yield of 1.70 kg/m**2; water productivity was 2.21 kg/m**3 in 2006 and 3.47 kg/m**3 in 2007. Seasonal ET was 418 mm for corn for silage with a yield of 1.52 kg/m**2 in 2006 and 671 mm in 2007 with a yield of 2.44 kg/m**2; water productivity was 3.63 kg/m**3 in 2006 and 3.64 kg/m**3 in 2007. Using the 2007 season as a better species comparison, forage sorghum can achieve comparable water productivity as corn with less ET (~73% of corn ET) and irrigation requirement although with a reduced yield (~62% of corn dry matter).

Last Modified: 7/11/2014
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