|Schneider, Arland -|
|Mustafa, Ahmed Taher -|
|Abou-Zeid, W.A. -|
Submitted to: Scientific and Technical Review
Publication Type: Research Notes
Publication Acceptance Date: December 23, 2010
Publication Date: January 14, 2011
Citation: Evett, S.R., Howell, T.A., Schneider, A.A., Todd, R.W., Mustafa, A.A., Abou-Zeid, W. 2011. Water requirements and management of maize under drip and sprinkler irrigation. 1999 annual report for Agricultural Technology Utilization and Transfer (ATUT) project. Scientific and Technical Review. pp 1-16. Technical Abstract: In the second year of this project, research continued at Ismailia, Egypt on irrigation management of maize, fava bean, wheat, and alfalfa. Research at Bushland, Texas, continued on alfalfa and grass reference evapotranspiration (ET), means of estimating those values from Bowen ratio meterological measurements, and means of predicting them from standard weather station measurements. Also at Bushland, research on automatic surface and subsurface drip irrigation of soybean was conducted using infrared thermometers to measure leaf temperature that was used by the irrigation controller in a feedback loop to control irrigations. Maize harvested at Ismailia yielded 2.84 tons/ha (44 bu/acre) after using 65 cm of water. This resulted in a water use efficiency of 0.44 kg m**-3, rather low compared with 1997 figures. The low yields were correlated with low soil water contents measured by the time domain reflectometry (TDR) system, and air temperatures between 28 and 30 deg C, both of which occurred during grain filling. The TDR system at Ismailia showed deep percolation losses of irrigation water under a regime of every-other-day drip irrigation of fava bean in fall 1998. Evidence of water movement to 3 m (10 ft) depth was clear. Recommendations for drip irrigation management on the sandy Eastern Desert soils are changed by this result, which indicates that more frequent, smaller irrigations are needed, in essence "spoon feeding" of water and nutrients to the crop. One corollary of this result is that drip irrigation probably cannot be controlled manually on these soils - electronic controllers should be used to achieve the small, frequent irrigations. At Bushland, soybean yields were up to 4.8 tons/ha (76 bu/acre) under automatic drip irrigation, and were significantly higher compared with yields from the previous best management practice that used weekly replenishment of soil water use as measured by the neutron probe. Yields were also higher than furrow irrigation results that average 40 bu/acre in a separate study. The Bowen ratio energy balance (BREB) system waas shown to over-estimate alfalfa ET under the windy, dry, and hot conditions of the semi-arid Southern Great Plains. This result makes questionable the use of the BREB method for estimation of crop water use in many irrigated areas of the western United States. Work and results from both Ismaila and Bushland were disseminated in newspaper and magazine articles, television interviews, scientific papers, and irrigation management training sessions.