Groundcovers Influence Citrus Yield and Water Use

Josh McGillIrrigation, Production, Tip of the Week

By Sandra M. Guzmán

In Florida citrus, black fabric mulch groundcovers have been used for the control of the invasive Diaprepes abbreviatus (root weevil). However, these groundcovers can also serve as a best management practice (BMP) to optimize tree water uptake and maintain nutrients around the root system.

A three-year University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) study from 2019 to 2021 assessed the effects of fabric mulch groundcovers in the water, plant root growth, and yield of lemon trees in a commercial setting. The U.S. Department of Agriculture’s National Institute of Food and Agriculture provided funding for the study.

Groundcovers influence young tree growth. The red line indicates differences in tree height.

Researchers collected and analyzed real-time soil moisture sensor data and environmental data (including rain, soil temperature, solar radiation and wind velocity) to provide daily irrigation recommendations for covered and uncovered beds. Then, they contrasted the total water applied per treatment with physiological variables such as root and canopy growth, trunk diameter and yield to assess the impacts of these fabric groundcovers.

The overall fruit weight was 30% higher for the ground-covered treatment than for the uncovered treatment. Similarly, canopy growth and trunk diameter increased with the groundcover. By using both soil moisture sensor-based irrigation and groundcovers, the water savings can be as much as 20%.

However, the study found that the soil type could be an influencing factor. Some locations in the experiment presented higher benefits than others. In addition, the frequency and timing of an irrigation event influences the beneficial effects of these kinds of BMPs. More frequent irrigation, but with less time and early in the morning (before 8:00 a.m.), could provide the biggest benefits.

Sandra M. Guzmán is an assistant professor at theUF/IFAS Indian River Research and Education Center in Fort Pierce.