|Schneider, Arland -|
|Mustafa, Ahmed Taher -|
|Abou-Zeid, W.A. -|
Submitted to: Scientific and Technical Review
Publication Type: Research Notes
Publication Acceptance Date: October 15, 2000
Publication Date: January 14, 2011
Citation: Evett, S.R., Howell, T.A., Schneider, A.A., Mustafa, A.A., Abou-Zeid, W. 2011. Water requirements and management of maize under drip and sprinkler irrigation. 2000 annual report for Agricultural Technology Utilization and Transfer (ATUT) project. Scientific and Technical Review. pp 1-17. Technical Abstract: Research at Ismailia, Egypt, focused on irrigation management of maize, fava bean, wheat, and alfalfa. In 1998, the two weighing lysimeters at Ismailia were recalibrated successfully with precision of 0.01 mm; and a state-of-the-art time domain reflectometry (TDR) system for soil water balance measurements was installed in the alfalfa and maize fields to 3-m depth in three replicates each. In 1997, maize yield at Ismailia was 2.76 Mg/feddan (19.7 Ardab/feddan). Water use was 54.4 cm (2285 m**3/feddan), and water use efficiency was 1.21 kg/m**3. In 1998, maize harvested at Ismailia yielded 2.85 Mg/ha (2536 lbs/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 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. Research at Bushland, Texas, was 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 and maize was conducted using infrared thermometers to measure leaf temperature that was used by the irrigation controller in a feedback loop to control irrigations. At Bushland, 1998 dry basis soybean yields were up to 4.8 Mg/ha (4286 lbs/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 averaged 2240 lbs/acre in a separate study. Water use efficiency ranged from 0.45 to 0.51 kg/m**3. Maize under automatic drip irrigation yielded up to 12.1 dry Mg/ha (10805 lbs/acre) in 1997 and 1999 (dry basis), compared with yields of up to 11.5 Mg/ha (10270 lbs/acre) under the previous best management practice. Water use efficiency was stable over years for the automatic irrigation system, averaging 1.48 kg/m**3, but was unstable under weekly replenishment, ranging from 0.65 to 1.52 kg/m**3. From 1997 through 1999, grass ET was not well-predicted by the Penman-Monteith (PM) equation (an international standard used for irrigation scheduling). Evapotranspiration was underpredicted at high ET rates in the windy, highly-advective environment at Bushland. This finding will improve crop water use estimates for irrigation scheduling in this region of the Southern High Plains. Over the same period, alfalfa ET was well predicted by the PM equation, a perhaps surprising result given the grass ET result. But, this result will enhance confidence of crop water use estimates and irrigation scheduling based on alfalfa reference ET in this region. The result also confirms the usefulness of alfalfa as a reference ET crop even in extreme climates, and supports its use at Ismailia. Alfalfa yields were 16.4, 20.6, and 15.2 dry Mg/ha in the three years of the project (14 600, 18 400, and 13 600 lbs/acre). In 1997 and 1998, the Bowen ratio energy balance (BREB) system was shown to overestimate alfalfa ET under the windy, dry, and hot conditions of the semi-arid Southern Great Plains. This result makes the use of the BREB method questionable for estimating crop water use in many irrigated areas of the western United States and in Egypt. Work and results from both Ismaila and Bushland were disseminated in newspaper and magazine articles, television and radio interviews, scientific papers, book chapters, irrigation management training sessions, and on the Internet at http://www.cprl.ars.usda.gov/.