Modeling the combined impacts of deficit irrigation, rising temperature and compost application on wheat yield and water productivity

Limited water resources and climate change in arid and semi-arid regions have negative impacts on food and water security. Management of irrigation and compost may be used to tackle this issue. Crop models are the powerful tools that could predict grain yield (GY) and water productivity (WP) under a broad range of irrigation, compost and temperature interactions. In addition, modeling irrigation management requires the selection of the most suitable evapotranspiration (ET) approach to achieve robust simulations. To achieve this goal, two crop models in Decision Support System for Agrotechnology Transfer (DSSAT) (i.e. CERES-Wheat and N-Wheat), were calibrated and evaluated using a field dataset of three growing seasons in a high-temperate region in Egypt (Luxor). Then, the models were applied to explore GY and WP across a wide range of irrigation (11 options) and compost (8 rates) interactions using two ET routines such as Priestley-Taylor (PT) and FAO 56 Penman-Monteith (PM). The models were also used to predict (GY) and (WP) within the same range of irrigation and compost interactions at higher temperatures (i.e. +1,2,3 and 4) compared to the baseline outputs (1981-2010). Simulation results showed that, deficit irrigation up to 80% and 85% from soil available water achieved the highest values of GY (7.5 t ha(-1)) and WP (18.4 kg ha(-1) mm(-1)) respectively, provided that using higher rate of compost (12 t ha(-1)). Rising temperature up to 4 degrees C decreased GY and WP by 17.2% and 7.4% respectively relative to the baseline without any benefits from compost. Compost technology does not help offset the negative impacts of temperature, but increased yield reduction and greenhouse gas emissions (GHG). Higher compost rates may be used to mitigate the effect of deficit irrigation on wheat yield and water productivity, but not compatible with mitigation of climate change in arid and semi-arid regions.