Use of low-quality water for irrigation in the Northeast Brazil: A review

Abstract

Water scarcity represents one of the greatest challenges for agricultural development, particularly in semi-arid regions such as Northeast Brazil. In this context, the use of alternative water sources, such as brackish waters and treated wastewater, has emerged as a crucial strategy to mitigate the impacts of water scarcity in the region. This study presents a literature review aimed at highlighting scientific contributions concerning the use of brackish waters and treated domestic wastewater for irrigation in Northeast Brazil. This survey focused on three main themes: the use of brackish waters for irrigation (addressing aspects such as alternating saline stress according to the crop’s phenological stage, leaching fractions to minimize salt accumulation in the soil, pulse irrigation, among others); the use of treated wastewater for irrigation (exploring treatments, as well as the physico-chemical and microbiological characterization of water for agricultural reuse, and its effects on plant growth and soil quality); and the impacts of low-quality waters on the hydraulics of irrigation systems. According to the results, the use of brackish waters is a viable alternative for regions facing water scarcity, especially when salt-tolerant plant materials are selected, and strategies are adopted (such as alternating irrigation according to the crop’s phenological stage, pulse irrigation, among others) to mitigate salt stress. Another promising source for expanding irrigated areas is the use of treated wastewater, particularly for cultivating forage species intended for animal feed. Another important aspect is the adoption of localized irrigation for applying these low-quality waters, as one of the main challenges is the risk of emitter clogging. Therefore, as a conclusion of this review, ensuring minimum living conditions for rural populations depends on public policies that promote the use of low-quality waters, such as brackish and treated wastewater (domestic sewage and gray water).