Irrigation with desalinated and raw produced waters: Effects on soil properties, and germination and growth of five forages

Abstract

Produced water is generated during oil and gas production in copious amounts daily in the United States. With increasing water shortfalls in arid and semi-arid regions, it could be a valuable source of water for irrigation purposes after treatment. The present study examined the effects of irrigation with produced waters on five perennials cool season forage, species western wheatgrass (Pascopyrum smithii), alfalfa (Medicago sativa), meadow bromegrass (Bromus biebersteinii), Russian wildrye (Psathyrostachys junceus), and tall fescue (Schedonorus arundinaceus). The forages were grown in a greenhouse, in loamy soil, and irrigated with desalinated reverse osmosis RO (231 mg/l), diluted RAW (1400 mg/l), RAW produced (8610 mg/l), and tap (427 mg/l) water. All forages were harvested three times at an interval of ≈ 90 days after 30 days germination period. Tall fescue germinated (100 %) and grew well under all four treatments. The higher biomass was with alfalfa, tall fescue, wheatgrass, bromegrass, and Russian wildrye, respectively. Evapotranspiration (ET) of the five species decreased with increasing soil and irrigation water salinity. Na, Cl, and B ions concentrations were 10.7, 13.6, and 42.3 mg/l, respectively in wheatgrass; 24.7, 17, and 14.5 mg/l, respectively in alfalfa; 27.7, 25.6, and 92.5 mg/l, respectively in bromegrass; 18, 14.6, and 59.6 mg/l, respectively in Russian wildrye; and 33, 35, and 207.5 mg/l, respectively in tall fescue, in plant tissues obtained after the second harvest. In soil, Na and B ions concentrations were 1173, 2.1 mg/l, respectively in wheatgrass pots; 1047, 1.7 mg/l, respectively in alfalfa pots; 874.6, 1.4 mg/l, respectively in bromegrass pots; 782, 1.6 mg/l, respectively in Russian wildrye pots; and 1974, 3.17 mg/l, respectively in tall fescue pots. Plant biomass decreased with increasing salinity; however, plants continued to grow even after the third harvest. Utilizing desalinated and diluted produced waters as a valuable source of water for irrigation after treatment could alleviate water demand in arid oil producing regions of the world.