Effects of irrigation uniformity on yield response and production economics of maize in a semiarid zone

Authors: NASCIMENTO, A.K. - University Of Castilla-La Mancha(UCLM); Schwartz, Robert; LIMA, F.A. - University Of Castilla-La Mancha(UCLM); LOPEZ-MATA, E - University Of Castilla-La Mancha(UCLM); DOMINGUEZ, A - University Of Castilla-La Mancha(UCLM); IZQUIEL, A - University Of Castilla-La Mancha(UCLM); TARJUELO, J.M. - University Of Castilla-La Mancha(UCLM); MARTINEZ-ROMERO, A - University Of Castilla-La Mancha(UCLM)

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2018
Publication Date: 10/5/2018
Citation: Nascimento, A., Schwartz, R.C., Lima, F., Lopez-Mata, E., Dominguez, A., Izquiel, A., Tarjuelo, J., Martinez-Romero, A. 2018. Effects of irrigation uniformity on yield response and production economics of maize in a semiarid zone. Agricultural Water Management. 211(2019):178-189. https://doi.org/10.1016/j.agwat.2018.09.051.
DOI: https://doi.org/10.1016/j.agwat.2018.09.051

Interpretive Summary: Optimized scheduling of irrigation for crops can reduce water and energy use and increase gross profit margin. However, the uniformity of the applied irrigation across the field can reduce the success of improved scheduling. The effect of a marginally acceptable irrigation uniformity on corn yield and profitability was studied. In a field where the crop received more irrigation than required, grain yields were maximized. When irrigation was scheduled to match crop requirements, grain yields were reduced by 8%. Although optimal scheduling met crop water requirements on an area-averaged basis, parts of the field received less than what the crop required because of marginal uniformity. Likewise, optimal irrigation scheduling resulted in 18% less gross profit margin compared with the field that received 16% more irrigation. Improvement of the productivity of water with optimized irrigation scheduling must ensure that equipment can achieve above average uniformity.

Technical Abstract: Optimized irrigation scheduling to better match applied water to crop requirements can reduce the consumptive use of water and energy, improve water use efficiency, and increase gross profit margin. However, the distribution uniformity of applied irrigation can modify how reduced water applications influence field-averaged performance, especially for crops sensitive to water stress. We evaluated the effect of irrigation uniformity on the yield and profitability of maize (Zea Mays L.) in Albacete, Spain in two adjacent sectors of a field managed according to optimized scheduling with MOPECO throughout the growing season to maximize grain yield without water stress (Sector S1) or irrigation scheduling determined by an experienced producer (Sector S2). Irrigation uniformity was evaluated using catch cans in both fields and grain yield was harvested within zones exhibiting 75% (Z1), 100% (Z2), and 125% (Z3) of area-averaged volume applications throughout the year. The mean coefficient of uniformity (CU) was 84.5% and net applied irrigation plus precipitation totaled 742 mm in S1 and 865 mm in S2. Mean grain yield in sector S2 approached the maximum expected yield of 18.4 Mg ha-1 and exhibited no significant differences in yield among zones. In contrast, sector S1 exhibited significant yield differences (p less than 0.05) among zones with a measured yield in Z3 of 18.5 Mg ha-1 with yield reduction of 1.6 Mg ha-1 and 4.0 Mg ha-1 in Z2 and Z1, respectively and a consequent area-averaged yield 8% less than S2. MOPECO-simulated grain yields exhibited similar magnitude and trends in yield for each of the sectors. Because of these yield differences and the relatively low cost of irrigation water, area averaged gross margin in S1 was 18% less compared with S2. Simulations with MOPECO over a range of CU’s demonstrated that improved irrigation uniformity increased area-averaged yields and gross margin. Improvement of water use efficiency with optimized irrigation strategies must ensure that equipment can achieve good uniformity.