Microirrigation and fertigation in citrus (Citrus spp.): Chronological advances

Citrus (Citrus spp.) belongs to an evergreen tree category, requires some kind of stress, either soil water deficit stress or low temperature stress for induction of flowering, depending upon agro-pedology of growing conditions. Soil physical properties participate to a greater extent in regulating the success of flowering, fruit setting intensity and yield, coupled with desirable quality traits compared to chemical properties with regard to fertilizers- and water-use-efficiency. Hence, water management via micro-irrigation and fertigation play a pivotal roles in production sustainability alongside orchard longevity. A number of studies have established varying savings (25-35%) on both fertilizers and irrigation water compared to overly tilted use of basin irrigation methods. Computation on stagewise nutrient and water application scheduling without compromising the recommended doses of fertilizers and irrigation has further aided in developing precision citriculture with reduced water footprints and improved water-and nutrient-use-efficiency. However, carbon footprint emphasizing soil-plant-environment inclusive studies in relation to coupling of irrigation and fertilization is still not a preferred research agenda, in addition to development of 4R (right amount of fertilizers at right growth stage in right form and right placement) 4W (right amount of water at right growth stage in right form and right placement, depending upon zone of feeder root concentration) strategy to economise both fertilizers and water use. Initial success on sensor-based sub-surface fertigation linking IOTs and machine learning, though has produced some encouraging results, but a long way in waiting before such developments are computerized at farm level from operation point of view.