|Evett, Steven - Steve|
|Baumhardt, Roland - Louis|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/17/2014
Publication Date: 9/17/2014
Citation: Evett, S.R., Oshaughnessy, S.A., Tolk, J.A., Colaizzi, P.D., Baumhardt, R.L., Schwartz, R.C. 2014. Enhancing water use efficiency with plant feedback irrigation control: The case for sorghum. Special Session China-US Water Saving Technology Flagship Project Workshop, 18th World Congress of CIGR. skp
Technical Abstract: Grain sorghum (Sorghum bicolor Moench L.) is a well-adapted and widely grown grain crop in the U.S. Southern High Plains and other semi-arid regions. Sorghum has several advantages over corn (Zea mays L.) in this region. Sorghum planting dates are more flexible, making it easier to plant as a companion crop with either corn or cotton (Gossypium hirsutum L.), the two most important cash crops in the region, such that the water use of sorghum peaks at a different time than that of the main crop (usually later). This allows limited irrigation well capacities to be fully utilized. And, sorghum is more tolerant of deficit irrigation management than is corn, which means that cut backs in irrigation are better tolerated, affording some protection against well capacity declines or well failures during the growing season. Sorghum often can be successfully grown with only a few early irrigations. In the 1930s, sorghum and corn yields were comparable, but corn yields have greatly outstripped sorghum since then due to extensive breeding, hybridization and genetic engineering research outcomes. We examined sorghum grain yield from 352 seasons of experimental work under a wide variety of water management practices. These included dryland and irrigated cultivation with conventional full tillage, stubble mulch tillage and no tillage during the period from 1962 to 2012. Irrigation regimes ranged from full replacement of crop water use to various levels and timings of deficit irrigation and included only pre-plant irrigation. On average, irrigation doubled water use efficiency (WUE = economic yield per unit of water consumed) compared with production that depended only on precipitation and stored soil water. Overall, irrigation to fully replace crop water use resulted in neither the largest yields nor the largest WUE values, possibly because it caused the sorghum crop to add more leaf area than needed to fill grain, thus reducing the harvest index. Both the largest yields and largest WUE values resulted from deficit irrigation regimes. In particular, the precision deficit irrigation regimes implemented using plant water stress sensing with infrared thermometers resulted in yield and WUE values that were consistently in the top five percent of all results.