- Ph.D. Biological Engineering; Agricultural & Biological Systems Engineering. University of Nebraska – Lincoln. 2020
- M.S. Mechanized Systems Management. University of Nebraska – Lincoln. 2013
- B.S. Agricultural Mechanization. University of Mosul, Iraq. 1999
Areas of Research and Professional Interest
• Soil-water resources/irrigation engineering; crop water use efficiency; variable rate irrigation and fertigation; and irrigation water management.
• Measurement of evapotranspiration, transpiration, evaporation, and crop water productivity; and spatio-temporal plant water extraction.
• Impact of climate variables and irrigation levels on crop yield and crop water productivity response of drought-tolerant hybrids.
• Impact of different irrigation levels, irrigation methods, and nitrogen timing application strategies on crop water use efficiency, yield, nitrogen efficiency indices, nitrogen loss through various pathways, and water and soil quality.
• Expertise in soil moisture sensors, evapotranspiration (ETc), irrigation management, and instruments of Leaf area index, SPAD, NDVI, Infrared Thermometer, and Prometer (stomatal resistance).
• Expertise in installation, maintenance and troubleshooting of various types of irrigation systems.
• Expertise in Agricultural research, and Project management.
• Expertise in field plot techniques and experimental field design.
Honors and Awards
- 2022: Engineer of the Year Award by the ASABE Nebraska Section.
- 2019: Bill A. and Rita L. Stout Outstanding International Graduate Student Award. University of Nebraska-Lincoln (UNL).
- 2019: Shear-Miles Fellowship Award. University of Nebraska-Lincoln (UNL).
- 2010: Iraqi Graduate Studies Program Scholarship by the Norman Borlaug Institute for International Agriculture at Texas A&M.
- Mohammed, A.T., Irmak. S., (2022) "Maize response to irrigation and nitrogen under center pivot, subsurface drip and furrow irrigation: Water productivity, basal evapotranspiration and yield response factors." Agricultural Water Management, 271, 107795.
- Mohammed, A.T., Irmak. S., (2022) "Maize response to coupled irrigation and nitrogen fertilization under center pivot, subsurface drip and surface (furrow) irrigation: soil-water dynamics, evapotranspiration (ETc) and irrigation vs. ETc relationships." Agricultural Water Management, 267, 107634.
- Irmak, S., Mohammed, A. T., Kukal, M. S. (2022) "Maize response to coupled irrigation and nitrogen fertilization under center pivot, subsurface drip and surface (furrow) irrigation: Growth, development and productivity." Agricultural Water Management, 263, 107457.
- Irmak, S., Mohammed, A. T., Kranz, W. L., van Donk, S., and Yonts, C. D. (2020). "Irrigation-yield production Functions and irrigation water use efficiency response of drought-tolerant and non-drought-tolerant maize hybrids under different irrigation levels, population densities and environments." Sustainability, 12, 358.
- Irmak, S., Kukal, M. S., Mohammed, A. T., Djaman, K. (2019). "Disk-till vs. no-till maize evapotranspiration, microclimate, grain yield, production functions and water productivity." Agricultural Water Management, 216, 177-195.
- Mohammed, A. T., Irmak, S., Kranz, W. L., van Donk, S., and Yonts, C. D. (2019). "Grain yield, crop and basal evapotranspiration, production functions and water productivity response of drought-tolerant and non-drought-tolerant maize hybrids under different irrigation levels, and population densities: Part I. In western Nebraska's semi-arid environments." Applied Engineering in Agriculture, 35(1), 61–81.
1. Mohammed, A.T., S. Irmak. July 20, 2022. Combined effects of full and limited irrigation, nitrogen fertilization timing on maize grain yield and evapotranspiration under different irrigation methods. ASABE Annual International Conference. July 18-21, Houston, Texas.