Irrigating Young Trees in High-Density Plantings

Tacy CalliesIrrigation

UF/IFAS photo by Thomas Wright

Florida citrus yields have declined by almost 56 percent since 2005. With such a large decrease, growers have been forced to replant trees at much higher densities to counter-balance tree loss.

In November 2017, researchers at the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Southwest Florida Research and Education Center (SWFREC) initiated a study to determine how much water is required to grow citrus trees at higher planting densities without reducing their productivity.

Recently, Said Hamido, post-doctoral research associate at the UF/IFAS SWFREC, presented results from the study during a virtual webinar. Eight-month-old citrus trees were transplanted at different densities with four irrigation treatments (very low, low, medium and high) of recommended rates for young citrus trees. Between 2017 and 2020, tree height, trunk diameter, leaf area, canopy volume, root growth, nutrient concentrations, stem water potential and water use were evaluated.

According to Hamido, the study grove included three densities (447, 598 and 745 trees per hectare) on two rows of beds replicated four times, and three densities (512, 717 and 897 trees per hectare) on three rows of beds replicated six times.

Each density was irrigated at one of two irrigation rates (62 or 100 percent) during the first 15 months. After that, irrigation rates were adjusted to represent 26.5, 40.5, 53 and 81 percent based on recommended crop evapotranspiration (ETc) for young citrus trees.

During the first year of the study, the 62 percent ETc irrigation treatment promoted citrus trees’ root and shoot development. After the first year, Hamido recommends bumping the irrigation rate up to 81 percent to significantly enhance tree growth, including height, trunk diameter and canopy volume.

Additionally, Hamido said that increasing the irrigation rate to 81 percent ETc has proven to promote root development, minimize nutrient loss and maintain adequate soil moisture. This results in better soil temperature, water potential and lower salinity when compared to other treatments.

Read more about high-density citrus plantings here.

This article was written by Ashley Robinson, AgNet Media communications intern in Gainesville, Florida.