By Davie M. Kadyampakeni and Alisheikh A. Atta
The conventional four Rs for nutrient management are right source, right place, right rate and right time. This approach allows growers to synchronize nutrient supply with crop demand, enhance tree health and fruit yield, and abate economic costs and environmental losses.
Photo by Alisheikh A. Atta
In contemporary farming systems in Florida citrus production, considering a fifth R — right irrigation rate or method — is crucial to determine the fate of the nutrients applied in the field. In Florida’s sandy soils with relatively low organic matter and water-holding capacity, crop water requirement-based irrigation is vital for citrus trees impacted by citrus greening. Annual rainfall is high, especially in the summer months of June through September, and sandy soil contributes to nutrient leaching and reduction in fruit yield and quality. Consequently, researchers have designed several tools to address challenges to current irrigation practices, such as deficit irrigation, drip and micro-sprinkler irrigation. These tools include irrigation-scheduling based on real-time weather data and crop water requirements.
Novel irrigation management practices based on crop-water demand in response to different (deficit, moderate and high) irrigation conditions are becoming the focus of study for sustainable citrus production. The new irrigation approaches were determined using a smart irrigation app developed by the University of Florida and found at Citrus App | SmartIrrigationApps.org, using daily reference evapotranspiration and weather data obtained from the Florida Automated Weather Network stations.
In an irrigation management study based on crop-water demand, the soil capacity to restore soil water around the root zone throughout the day and the season was improved. As a result, trees developed significant fibrous root length densities, median root lifespan and enhanced leaf nutrient concentration. Moreover, split nutrient applications coupled with scheduled irrigation enhanced both nutrient- and water-use efficiency, thereby protecting the downstream ecosystems and averting further environmental degradation from excess nutrient loads.
Davie M. Kadyampakeni is an associate professor and Alisheikh A. Atta is a postdoctoral research associate at the University of Florida Institute of Food and Agricultural Sciences Citrus Research and Education Center in Lake Alfred.
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