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New Mexico State University (2016)

Irrigation using brackish groundwater and RO concentrate : effects on germination, emergence, and growth of halophytes

Ozturk Omer F.

Titre : Irrigation using brackish groundwater and RO concentrate : effects on germination, emergence, and growth of halophytes

Auteur : Ozturk Omer F.

Université de soutenance : New Mexico State University

Grade : Master of Science (MS) 2016

Résumé
In the arid and semi-arid southwestern United States including New Mexico, water scarcity and salinity is a crucial problem. The low rainfall, high evapotranspiration (ET), low quality groundwater, and declining amounts of surface water have led to attempts to find potable water for both human consumption and sustainable agricultural demand. The Brackish Groundwater National Desalination Research Facility (BGNDRF) in Alamogordo, New Mexico uses a reserve osmosis (RO) system to desalinate water, but the process results in a highly saline RO concentrate that must be disposed of in an environmentally safe way to. This study examines the potential of reusing the concentrate for irrigating salt tolerant plants. The objective of this study was to improve knowledge of six candidate halophyte species (Atriplex canescens, Hordeum vulgare, Lepidium alyssoides, Distichlis stricta, Panicum virgatum and xTriticosecale) for cultivation on brackish groundwater and RO concentrate land application sites by (1) testing the germination and emergence of six halophyte species under an irrigation water salinity gradient (Chapter 1), (2) determining ET, and volumetric leaching fractions (LF), (3) comparing dry biomass yields of two halophytes species (Hordeum vulgare and xTriticosecale) under an irrigation water salinity gradient, and (4) assessing irrigation water salinity effects on irrigated sandy loam soil (Chapter 2). Experiments with six halophytes species (Atriplex canescens, Hordeum vulgare, Lepidium alyssoides, Distichlis stricta, and xTriticosecale) were carried out for 30 days in a greenhouse. Four irrigation water treatments were used : irrigation with tap water (EC 0.8 dS/m), brackish groundwater (EC 5.0 dS/m), RO1 concentrate water (EC 8.0 dS/m), and RO1 concentrate mixed with NaCl (RO2 ; EC 10 dS/m). Results of the germination percentage showed that H. vulgare and xTriticosecale had no significant difference with higher germinations under salinity treatments, and other species showed similar germinations under higher salinity treatments. On the other hand, D. stricta seeds displayed lower germinations under higher salinity treatments. Results of the emergence percentage showed that H. vulgare and xTriticosecale had no significant difference with higher emergence under higher salinity treatments, while other species showed similar emergence percentages under higher salinity treatments. In contrast, L. alyssoides and A. canescens seeds showed lower emergence percentage under higher salinity treatments. Increasing irrigation water salinity increased mean germination time for all species except L. alyssoides, but did not affect the germination percentage significantly except for A. canescens. Increasing irrigation water salinity increased mean emergence time for all species except L. alyssoides, but did not affect the emergence percentage for H. Vulgare, xTriticosecale, and P. virgatum species significantly. A 90-day greenhouse experiment was conducted at the Fabian Garcia Science Center in Las Cruces, NM. Two salt tolerance plant species, Hordeum vulgare, and xTriticosecale, were planted in pots packed with sandy loam soil to a constant bulk density. Plants were arranged in a completely randomized design and irrigation treatments were applied for 90 days in two seasons. The amount of irrigation and deep percolation (DP) was measured to determine ET and LF for the two-plant species. Results showered that total mean ET was generally higher and total mean DP was lower for plants irrigated with control water than the saline water. An increase in irrigation water salinity increased total mean LF but plant total mean ET decreased. Dry biomass was determined by cutting the plant at the soil surface and drying at 65°C. Results showed that dry biomass for H. vulgare increased with increasing irrigation water salinity in season two, while decreased for xTriticosecale with increasing irrigation water salinity in season two statistically. Soil measurements (ion content, EC, SAR, and pH) and ion uptake of plants were taken at the conclusion of the study. Additionally, the cores were packed with sandy loam to a constant bulk density, and were saturated with saline water treatments to determine saturated hydraulic conductivity, and volumetric water content. Results showed that the concentrations of Mg⁺², Na⁺, Ca⁺², and Cl⁻ ions increased with irrigation water salinity in the sandy loam-grown plants and in the irrigated sandy loam soil. Sandy loam soil cores had no statistically significant difference for the hydraulic conductivity among water salinity treatments. The volumetric water content across treatments had significant difference at the saturation pressure (0 MPa).

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Page publiée le 13 avril 2017, mise à jour le 24 décembre 2019