Growth, Evapotranspiration, and Ion Uptake Characteristics of Alfalfa and Triticale Irrigated with Brackish Groundwater and Desalination Concentrate

V Kankarla,M K Shukla,B.J Schutte,G.A Picchioni,D Vanleeuwen

doi:10.3390/agronomy9120789

Abstract

Persistent drought, low snowfall, and low rainfall have reduced availability of fresh water for irrigating agricultural crops in many arid and semi-arid regions of the world. Brackish groundwater (electrical conductivity; EC > 3 dSm−1) is increasingly used for irrigation in New Mexico. This study investigates the effect of ion uptake from brackish groundwater and concentrate irrigation on the performance of two forage species, alfalfa (Medicago sativa) and triticale (×Triticosecale), in sand soils in greenhouse conditions. Two simultaneous experiments were run for 90 days using tap water (control; 0.7 dSm−1), brackish groundwater (BGW; 4 dSm−1), reverse osmosis concentrate (RO; 8 dSm−1, Ca2+ dominant), and BGW plus sodium chloride (BGW + NaCl; 8 dSm−1, Na+ dominant). BGW + NaCl irrigation significantly reduced the evapotranspiration (ET) of both the species. Deep percolation (DP) increased significantly with RO and BGW + NaCl irrigation in alfalfa but only with BGW + NaCl irrigation in triticale. Alfalfa plant growth decreased with increasing salinity, while triticale plants followed an opposite trend. ET continued to decrease with increasing salinity for both species. Na+ dominant (BGW + NaCl) irrigation produced robust growth and early flowering and ear head formation in triticale. Na+ ion concentration in shoots was above 0.66%, which led to reduced alfalfa growth, while more than 1.22% did not decrease triticale growth or biomass. Increased Ca2+ sequestration in alfalfa played a crucial role in reducing Na+ ion toxicity. Species performance primarily confirmed that alfalfa is moderately salt-tolerant while triticale is confirmed to be a halophyte producing abundant growth and biomass with higher Na+ uptake. Triticale proved to be a promising species for reuse of RO concentrate for agriculture in marginal lands.

Highlights

Water is the primary basis of survival for all forms of life on the earth
The brackish groundwater (BGW) was obtained from the Brackish Groundwater National Desalination Research Facility (BGNDRF) in Alamogordo, NM, USA
On 10 November 2017, a shade was installed inside the greenhouse for five days to direct sunlight, and this dropped the mean daily light integral (DLI) to 0.1 mol m−2 day−1 (Figure 1C)

Summary

Introduction

Water is the primary basis of survival for all forms of life on the earth. With increasing global population, pressure on available water resources from industries and urbanization has grown. The availability of fresh water is becoming scarce in arid and semi-arid regions of the world. Under these circumstances, brackish water, which is variably saline, is used to supplement irrigation shortfalls. In New Mexico, a semi-arid state in the southwestern USA, about 75% of the aquifers are brackish with salinity higher than 3 dSm−1 [4,5]. In these regions, brackish groundwater (BGW) is used for irrigating agricultural crops, which can potentially reduce crop productivity. Yordanov et al [8] suggested the use of drainage water, seawater, and recycled water for crop production as a part of a solution to water scarcity, while Babcock et al [9] utilized treated saline wastewater effluent as a source of irrigation to cultivate salt-tolerant species

Methods

Results

Discussion

Conclusion