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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #338063

Research Project: Modeling Soil and Soil-plant Interaction Responses to Wind and Extreme Precipitation and Temperature Events under Different Management Strategies

Location: Rangeland Resources & Systems Research

Title: Development of an irrigation scheduling software based on model predicted crop water stress

Author
item Gu, Z - McGill University - Canada
item Qi, Z - McGill University - Canada
item Ma, Liwang
item Gui, D - Chinese Academy Of Sciences
item Xu, J - Hohai University
item Fang, Q - Qingdao Agricultural University
item Yuan, S - Jiangsu University

Submitted to: Computers and Electronics in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2017
Publication Date: 11/1/2017
Citation: Gu, Z., Qi, Z., Ma, L., Gui, D., Xu, J., Fang, Q., Yuan, S. 2017. Development of an irrigation scheduling software based on model predicted crop water stress. Computers and Electronics in Agriculture. 143:208-221. http://dx.doi.org/10.1016/j.compag.2017.10.023.

Interpretive Summary: An irrigation scheduling software based on RZWQM2 model predicted crop water stress was developed and evaluated. The timing of irrigation was based on the occurrence of model-simulated water stress, while the depth of irrigation was based on the fraction of the soil moisture deficit (K) needed to replenish the soil water content (') at any given time to field capacity. The predicted water stress for different K values was tested based on RZWQM2 model calibrated against data collected in a drip-irrigated corn (Zea mays L.) field near Greeley, Colorado, USA between 2008 and 2010. In the field, water losses through potential crop evapotranspiration (ET) were fully met through irrigation at 3-7 day intervals. Compared to this ET and water balance based field irrigation regime, the simulated full irrigation (K =1) water stress-based irrigation regime saved 30.5%, 17.3% and 7.1% in seasonal irrigation from 2008-2010, whereas more limited irrigation (0.6 = K = 0.9) provided water savings of as much as 35%, 30%, and 16%, respectively. These water savings were a result of the water stress-based irrigation regime maintaining sufficient water to meet crop root water uptake requirements without constantly fully recharging the soil, thereby minimizing evaporation from the soil surface and soil water storage after grain filling.

Technical Abstract: Modern irrigation scheduling methods are generally based on sensor-monitored soil moisture regimes rather than crop water stress which is difficult to measure in real-time, but can be computed using agricultural system models. In this study, an irrigation scheduling software based on RZWQM2 model predicted crop water stress was developed and evaluated. The timing of irrigation was based on the occurrence of model-simulated water stress, while the depth of irrigation was based on the fraction of the soil moisture deficit (K) needed to replenish the soil water content (') at any given time to field capacity. The predicted water stress for different K values was tested based on RZWQM2 model calibrated against data collected in a drip-irrigated corn (Zea mays L.) field near Greeley, Colorado, USA between 2008 and 2010. In the field, water losses through potential crop evapotranspiration (ET) were fully met through irrigation at 3-7 day intervals. Compared to this ET and water balance based field irrigation regime, the simulated full irrigation (K =1) water stress-based irrigation regime saved 30.5%, 17.3% and 7.1% in seasonal irrigation from 2008-2010, whereas more limited irrigation (0.6 = K = 0.9) provided water savings of as much as 35%, 30%, and 16%, respectively. These water savings were a result of the water stress-based irrigation regime maintaining sufficient water to meet crop root water uptake requirements without constantly fully recharging the soil, thereby minimizing evaporation from the soil surface and soil water storage after grain filling. Under the water stress-based irrigation regime, the lesser quantity of water supplied at each of the irrigation events saved water over the full growing season by decreasing the average soil moisture content. Crop yields were largely the same under the water stress based irrigation regimes where K = 0.6; therefore, irrigation scheduling based on model-predicted water stress has the potential to provide greater water use efficiency. Further work is needed to install this system in an irrigated field and test its performance under different climate and soil conditions.