See the details of a UF/IFAS field trial that tested whether soil amendments could help citrus trees improve water use.
“Florida is currently experiencing one of the most severe droughts in the past 25 years,” shared a UF/IFAS Tip of the Week article; the article added that the drought is “putting HLB-affected trees under intense water stress.” Citrus trees affected by HLB, also known as citrus greening, have a smaller root ball, making it harder for them to take up water and nutrients. The article shared the details of a field trial started in 2025 to test if soil amendments like biochar and compost could “be effective in helping sandy soil retain water and nutrients while increasing organic matter.” See the details below.
Field Trial Details
According to the article, “a field trial was initiated in May 2025 on a commercial Polk County grove using 4- to 5-year-old Valencia trees grown on 100% Candler fine sand. Treatments included five biochar:compost ratios (0:100, 25:75, 50:50, 75:25 and 100:0), which totaled 4 pounds of amendments per tree with an untreated control added. For example, the 25:75 treatment was 1 pound of biochar with 3 pounds of compost. Amendments were added in May 2025, October 2025 and March 2026 with only compost added in March (no biochar). The amendments were lightly incorporated under the canopy using metal rakes.”
Details of Results So Far on Soil Amendments
The article shared that “On May 7, 2026, record-breaking temperatures reaching up to 96 degrees occurred in Central Florida during an already severe drought. Stomatal conductance, measured throughout the day, reflects how effectively a tree can uptake water and maintain gas exchange under stress.”
As part of the field trial, “Measurements were taken at 9:30 a.m. (pre-irrigation), 12:00 p.m. (right after a 30-minute irrigation) and 2:30 p.m. (2.5 hours after irrigation).”
The article shared that “While all treatments responded to irrigation…the 25:75, 0:100 (highest compost), and 100:0 (highest biochar) biochar:compost treatments maintained significantly higher stomatal conductance than the untreated control at 2:30 p.m.” The article explained that “This indicates improved ability to utilize limited water, supporting sustained productivity and reducing drought stress.”
Though the field trial is still ongoing, the article advised that “Although still early in the field trial, these results provide strong evidence that soil amendments can improve water use and maintain productivity under drought and extreme heat conditions. Additional benefits, including reduced nutrient leaching and enhanced soil microbial activity, support a more holistic approach to managing abiotic stress in HLB-affected citrus.”
Griffin Fertilizer is committed to helping both growers and ranchers make sound agronomic and economic decisions in order to maximize the health of their grove and pasture. As a full-service custom dry & liquid fertilizer blender and crop protection product distributor, we will continue our mission to further advance Florida agriculture. For questions or concerns about your farm or pasture, contact us and one of our team will be in touch.