Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 25, 2010
Publication Date: November 2, 2010
Citation: Tolk, J.A., Evett, S.R., Howell, T.A. 2010. Lower Limits of Water Use By Cotton, Maize, and Grain Sorghum in Three Great Plains Soils [abstract]. ASA-CSSA-SSSA Annual Meeting, October 31-November 3, 2010, Long Beach, California. 2010 CDROM. Technical Abstract: Accurate knowledge of the amount of soil water available for crop use helps agricultural producers select cropping and irrigation management strategies that maximize crop yields. Using neutron attenuation, we measured the lower limits of soil water content (LL, in m**3 m**-3) at harvest (three seasons each) of short-season maize (Zea mays L.), grain sorghum [Sorghum bicolor (L.) Moench], and cotton (Gossypium hirsutum L.) grown in lysimeters containing monoliths of clay loam, silt loam, or sandy loam. The objectives were to compare a crop's LL to the water content held at 1.5 MPa (LL 1.5) among soil types and to compare the LL of crops within a soil type. The depth of water in a 2.2-m profile at LL (LLmm) in the clay loam averaged 448(plus or minus 7) mm for cotton, 533(plus or minus 18) mm for maize, and 473(plus or minus 34) mm for sorghum and depth of water at LL-1.5 (LL-1.5mm) was 425(plus or minus 33) mm. In the silt loam, LLmm was 272(plus or minus 7) mm for cotton, 358(plus or minus 27) mm for maize, and 289(plus or minus 12) mm for sorghum and LL-1.5mm was 343(plus or minus 13) mm. The LL-1.5mm was 286(plus or minus 20) mm in the sandy loam; and LLmm was 249(plus or minus 31) mm for cotton, 312(plus or minus 14) mm for maize, and 260(plus or minus 15) mm for sorghum. The maize LL tended to be similar to or contain more water than LL-1.5, and cotton and sorghum tended to be similar to or contain less water than LL in the three soils except for sorghum in the clay loam. Crop specific LL values may also have been impacted by variations in climate among crop years and the presence of the calcic horizon in the sandy loam and clay loam. Knowledge of the LL of crops in a particular soil not only allows producers to understand crop yield and water use relationships, but it is also important for the management of irrigation water supplies.