Drip irrigation enhances shallow groundwater contribution to crop water consumption in an arid area

Abstract

Shallow groundwater plays a key role in agro‐hydrological processes of arid areas. Groundwater often supplies a necessary part of the water requirement of crops and surrounding native vegetation, such as groundwater‐dependent ecosystems. However, the impact of water‐saving irrigation on cropland water balance, such as the contribution of shallow groundwater to field evapotranspiration, requires further investigation. Increased understanding of quantitative evaluation of field‐scale water productivity under different irrigation methods aids policy and decision‐making. In this study, high‐resolution water table depth and soil water content in field maize were monitored under conditions of flood irrigation (FI) and drip irrigation (DI), respectively. Groundwater evapotranspiration (ETg) was estimated by the combination of the water table fluctuation method and an empirical groundwater–soil–atmosphere continuum model. The results indicate that daily ETg at different growth stages varies under the two irrigation methods. Between two consecutive irrigation events of the FI site, daily ETg rate increases from zero to greater than that of the DI site. Maize under DI steadily consumes more groundwater than FI, accounting for 16.4% and 14.5% of ETa, respectively. Overall, FI recharges groundwater, whereas DI extracts water from shallow groundwater. The yield under DI increases compared with that under FI, with less ETa (526 mm) compared with FI (578 mm), and irrigation water productivity improves from 3.51 kg m−3 (FI) to 4.58 kg m−3 (DI) through reducing deep drainage and soil evaporation by DI. These results highlight the critical role of irrigation method and groundwater on crop water consumption and productivity. This study provides important information to aid the development of agricultural irrigation schemes in arid areas with shallow groundwater.

Drip irrigation with organic fertilizer application improved soil quality and fruit yield

“…The salt concentration of groundwater was generally 5-10 g L -1 (Li & Nian, 1999). It may be that the continuous drip irrigation application caused a lower local groundwater level and mitigated the influence of groundwater on the surface salt accumulation (Karimov, Šimůnek, Hanjra, Avliyakulov, & Forkutsa, 2014;Wang, Huo, Guan, Guo, & Qu, 2018). On the other hand, after the application of organic fertilizer, soil organic matter improved soil physical and chemical properties and enhanced the soil water retention capacity (Maltas, Charles, Jeangros, & Sinaj, 2013;Wu et al, 2013), and organic fertilizer had a lower content of salt ions compared with mineral fertilizer.…”

Steady Water Flow with Interacting Point Source–Point Sink–Water Table in a Cylindrical Soil Domain

“…The previously derived analytical solution for steady infiltration from a point source into a finite cylindrical domain was used to analyze the effects of geometry, soil type, and lower boundary conditions on the flow fields and WUR of subsurface point sinks, with or without a surface point source in the presence of a shallow WT. This analysis is relevant to the water flow and uptake processes occurring in either natural fields with shallow groundwater (Wang et al, 2018) or artificial lysimeters (Groh et al, 2016). The linearized steady water flow equation and the suggested, coupled source–sink–WT approach allow evaluating the two independent—point source and WT—contributions to the WUR when acting separately and also both contributions when acting together.…”

A unique vadose zone model for shallow aquifers: the Hetao irrigation district, China

“…Here, we selected the Brooks-Corey model for its simplicity. The Brooks-Corey model can be expressed as (Gardner et al, 1970a, b;Mccuen et al, 1981;Williams et al, 1983)…”