Arunesh Kumar Singh, Shreya, Shahida Khatoon, D. K. Chaturvedi, Umakanta Choudhury, Ashok Yadav, Gulshan Sharma
Nowadays, optimal irrigation is essential to maintain global food security because it increases agricultural productivity in areas with limited water availability and makes it possible to grow crops in dry and semi-arid climates. Smart irrigation systems integrate conventional and intelligent control techniques to overcome water scarcity problems. This study reports advancements in intelligent control methods and smart irrigation systems using a hybrid review methodology that combines bibliometric analysis and narrative literature review. The analysis was carried out using VOSviewer software, based on 3,003 publications from 2010 to 2024 that were obtained from the Scopus database using keywords like irrigation system, Internet of Things, artificial intelligence, and sustainability. In conventional controllers such as PID controllers, we emphasize the systems or models with controlled parameters such as soil moisture, climatic factors (like temperature, humidity, and atmospheric pressure), and Soil factors (like fertilizer, pH, and salinity). In addition to this, the intelligent controllers have a learning mechanism, which makes them adaptive, indispensable, and different from conventional controllers. The paper deals with conventional controllers as well as intelligent controllers developed for irrigation to make the system smart, which reduces the wastage of water, improves production, and environmental sustainability in terms of their impact, advantages, key limitations, and future directions.