A field-modeling study for assessing temporal variations of soil-water-crop interactions under water-saving irrigation strategies

Abstract

a b s t r a c tSimulation models are useful tools that may help to improve our understanding of soil-water-plant interactions under innovative water-saving irrigation strategies. In this study, the HYDRUS-2D model was applied to evaluate the influence of deficit irrigation (DI) and partial root-zone drying (PRD) on maize water extractions during two cropping cycles of 2010 and 2011. The model was calibrated and validated using measured soil water content data (expressed as equivalent water depths). Reliable estimates of soil water content were provided by HYDRUS-2D, with root mean square error and mean bias error values of 2.3-5.11 and 1.63-4.93 mm, respectively. Root water uptake and maize grain yields were reduced by 13.2-28.8% and 13.6-52.8%, respectively, under different water-saving irrigation treatments compared to full irrigation. However, different root and water repartitions in the PRD treatment with a 25% reduction in the irrigation depth (PRD 75 ) improved soil water utilization and consequently, crop growth. Increased root water uptake (2.2-4.4 times higher than in other treatments) from the 60-100 cm soil depth in the PRD 75 treatment maintained a favorable daily evapotranspiration rate, resulting in no significant reduction in maize grain yield compared to full irrigation. Consequently, a 15.7-85% increase in water use efficiency for maize cultivation under PRD 75 ensured 25% water savings without threatening food security in the study area. It can be concluded that HYDRUS-2D can be successfully used to optimize water management under local water-stress conditions.

An application of the water footprint assessment to optimize production of crops irrigated with saline water: A scenario assessment with HYDRUS

“…A regular alternation of irrigated and non-irrigated sides of the crop under PRD results in the secretion of root-generated Abscisic Acid (ABA) (Schachtman and Goodger, 2008), which is transported to shoot regulating stomata of the leaves. Such regulation reduces crop water losses through stomata, while maintaining crop CO 2 adsorption at the favorable level (Kang and Zhang, 2004), which consequently results in a higher crop water use efficiency compared to DI, or even FI (Karandish and Šimůnek, 2016a).…”

“…In these regions, there is room for savings of fresh water if crops receive less irrigation water during their growing season (Karandish and Šimůnek, 2016a). In this regard, many researchers have investigated the economic and environmental consequences of applying deficit irrigation (DI) (Payero et al, 2006;Klocke et al, 2004;Stone, 2003) or partial root-zone drying (PRD) (Dry and Loveys, 1998;Kang and Zhang, 2004;Kirda et al, 2004;Shao et al, 2008;Tang et al, 2005;Karandish andŠimůnek, 2016a, 2016b).…”

“…Instead of carrying out laborious, time-consuming, and thus expensive field investigations with a limited number of treatments, an optimal N application rate can be estimated using a modeling approach (Karandish and Šimůnek, 2016a(Karandish and Šimůnek, , 2016b(Karandish and Šimůnek, , 2017. This may be especially advantageous in situations where it may be economically or technically impossible to carry out the project in the field (Li and Liu, 2011).…”

“…The concept behind PRD is different than behind DI and thus soil-watercrop relationships may be affected by these differences. While the HYDRUS model has been previously used to simulate soil water and nutrient dynamics under PRD (Karandish and Šimůnek, 2016a(Karandish and Šimůnek, , 2016b(Karandish and Šimůnek, , 2017, this has not yet been done while taking into account simultaneously both water and salinity stresses and their effects on soil-watercrop relationships. (ii) Similarly, little research has been carried out to find optimal management strategies with respect to both economic and environmental factors.…”

“…After sowing, the experimental plots were irrigated every other day during both growing seasons. For the FI treatment, the net irrigation depth ( I [ ] n FI , mm) was calculated as follows (Karandish and Šimůnek, 2016a(Karandish and Šimůnek, , 2016b(Karandish and Šimůnek, , 2017: Soil water content (SWC) measurements TDR probes were used at least two times a day to measure SWCs in 5-cm depth increments during both growing seasons. Moreover, information about the movement of the wetting front during irrigation events was collected at least 10 times in each treatment by measuring SWCs one hour before, and immediately and 2, 6, 12, 24, 48, 72, and 96 hours after irrigation events in the 2010 growing seasons.…”