Significance of aerated drip irrigation: A comprehensive review
Hao Li, Abdul Rahim Junejo, David J. Midmore, Shakeel Ahmed Soomro
Abstract
In recent years, aerated drip irrigation (ADI) has emerged as an innovative practice for efficient irrigation. It offers new approaches for the synchronized delivery of water and air, thereby enhancing the economic benefits of crops. Most previous studies have concentrated on the impact of imposed aeration within the irrigation stream on the soil environment and crop growth; increasing dissolved or soil air oxygen concentration in the root zone resulting in healthy root growth in otherwise unfavorable hypoxic soil conditions. However, the microbubbles (MBs) in irrigation water generated by aeration equipment serve multiple purposes. They are involved not only in the distribution of water and air through drip irrigation systems but also in the functional integrity of emitters and in altering the soil habitats in the crop root zone through various biochemical and biophysical mechanisms. Micro- and nano-bubble-mediated changes to the drip irrigation system and the soil microenvironment in the crop root zone have localized effects on microbial community aggregation, leading to significant ecological consequences. We outline the use of chemical gas filling (a weak solution of a peroxide directly into the rhizosphere) and mechanical gas filling devices (air compressors, venturi injectors, twin vortices, fluid oscillators, and micro-nano bubble (MNB) generators). This review emphasizes the role of ADI in improving crop growth, soil conditions, microbial populations and the management of emitter clogging in drip irrigation systems. Subsequently, we explore the key issues that need to be addressed in current ADI technology and discuss how micro- nano-bubble-induced alterations in the microenvironments of both the drip irrigation system, and the root zone soil can be harnessed. This approach can help manage and manipulate microbial communities, combat clogging in drip irrigation emitters, improve soil conditions for plant growth, and ultimately increase crop yields, resulting in a viable option for farmers world-wide. • Aerated drip irrigation (ADI) integrates oxygen-water co-transport and root delivery. • Rhizosphere hypoxia is alleviated, stimulating root proliferation and nutrient uptake. • In general, important functional soil bacterial communities are enhanced. • Micro-nano bubbles and peroxides minimize emitter clogging through biofilm disruption. • Irrigation uniformity, crop yields and quality all benefit from adaptive ADI.