Applying partial root drying drip irrigation in the presence of organic mulching. Is that the best irrigation practice for arid regions? Field and modelling study using the saltmed model

Abstract This research aimed at investigating the impact of irrigation systems, a deficit irrigation strategy and organic mulching using rice straw on maize water productivity in Egypt's arid conditions. The field experiment included 16 treatments over 2 seasons, 2015 and 2016. Irrigation systems were a drip irrigation system (DIS) and a furrow irrigation system (FIS), while the irrigation strategies were 100% full irrigation (FI), 75% FI, 50% FI and partial root drying (PRD). Organic mulching using rice straw (OMRS) was also investigated. The experimental results indicated that there was a positive impact of applying a PRD strategy by drip irrigation in the presence of organic mulching on the yield (12.6 t ha‐1 for 2015 and 12 t ha‐1 for 2016) and on the water productivity of maize (4.81 kg m‐3 for 2015 and 4.58 kg m‐3 for 2016), but under the control treatment (FIS with 100% full irrigation and without organic mulching) yield was 7.22 t ha‐1 for 2015 and 7.34 t ha‐1 for 2016 and water productivity of maize was 0.64 kg m‐3 for 2015 and 0.62 kg m‐3 for 2016. The SALTMED model simulated reasonably well the soil moisture and salinity distribution as well as maize dry matter, yield and water productivity for all treatments, with R2 of 0.998, 0.997 and 0.996, respectively. The results support the use of a PRD strategy by a drip irrigation system accompanied by an organic mulch of rice straw instead of the commonly used furrow irrigation. The PRD would save more fresh water, achieve higher yields and water productivity. In addition, mulching would reduce evaporation losses, retain soil moisture and increase organic matter content. © 2018 John Wiley & Sons, Ltd.