Innovations in Clay-Based Irrigation Technologies—A Systematic Review

Arid and semi-arid areas are suffering from declines in fresh water availability, making food security in these regions strongly dependent on the adaptability of agricultural production to the minimum usage of irrigation water. In response to this critical need, efforts have been directed towards enhancing irrigation efficiency and exploring innovative clay-based subsurface irrigation systems. These systems use clay materials as porous emitters and operate on the principle of capillary water movement from the pottery to the root zone, effectively reducing water evaporation and demonstrating significant water-saving potential. This article presents the results of a systematic literature review, with a specific focus on identifying recent developments and innovations in clay-based subsurface irrigation technologies, describing cases of applicability and indicating directions for future research. This review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and involved the screening of 233 articles that were found through searches on the databases Web of Science and Science Direct combined with searches of Google Scholar and citation searches. As a result, 58 research articles were investigated. The webtool Rayyan was used for the screening of the articles and the synthesis of the results. The spectrum of clay-based irrigation systems identified in the investigated articles includes traditional methods such as clay pot and clay pipe irrigation as well as more recent advancements in the field such as Subsurface Irrigation with Ceramic Emitters (SICE), Self-regulating Low-Energy Clay-based Irrigation (SLECI), and Ceramic Patch Subsurface Drip Irrigation Line (CP-SDIL) and pottery dripper technologies. This paper offers a comprehensive analysis of each irrigation system, highlighting their main characteristics, advantages, and limitations. Particular attention is paid to the reported outcomes related to yield responses, water use efficiency, and suitability for various agricultural applications. This review indicates as a primary benefit of these systems their potential to allow water conservation, which is especially advantageous in regions with a restricted irrigation water supply. However, a major drawback is the challenge of scaling these systems effectively. Hence, the recommended areas for future research centre on the necessity of substantial economic assessments of and discussion on the potential social impact to promote the scalability of clay-based irrigation systems.