Biochar, Citrus Soil Health, and HLB Management

Citrus greening, also called Huanglongbing or HLB, is one of the most serious diseases affecting citrus growers. It damages tree roots and leaves, reduces fruit quality and yield, and can eventually make infected trees unproductive. There is currently no cure for HLB.

Early observations from University of Florida researchers raised an interesting question about biochar and citrus trees. They found larger trees and major differences in soil quality where carbon-rich material was present. The findings did not show that biochar cures or treats citrus greening, but they pointed to possible soil benefits worth studying.

Why Citrus Greening Is So Difficult

HLB is linked to a bacterium spread by the Asian citrus psyllid, a small insect that feeds on citrus trees. According to UF/IFAS, infected trees can develop damaged roots, thinning leaves, dying branches, fruit drop, and small or misshapen fruit.

The disease also makes it harder for roots to take up water and nutrients. Good nutrition, irrigation, and soil management can help support affected trees, but these practices do not remove the infection.

What Researchers Observed

In 2012, UF/IFAS researchers Arnold Schumann and Timothy Spann reported unusual results from four-year-old citrus trees growing where old burn piles had once been located. The soil in these areas was dark and contained carbon left behind from burned wood and other plant material.

Trees growing in the carbon-rich soil had 67% more canopy volume than trees in nearby untreated soil. The soil also contained more carbon and had 4.5 times greater cation exchange capacity, or CEC. CEC measures how well soil can hold certain nutrients that plants need.

What the Findings Mean

The results gave researchers a reason to study biochar more closely in Florida citrus groves. Many Florida groves have sandy soils that do not hold water and nutrients well. Biochar can help soil retain both, which could make it useful for supporting soil and root health.

There was an important limit to the research, however. The trees were growing where old burn piles had changed the soil. Researchers had not applied known amounts of biochar to controlled test plots. Because of this, they could not say that biochar caused all of the differences they observed. Instead, the research suggests that biochar could have a role in supporting soil and root health as part of a larger citrus-management program.

What We Can Take From the Research

The Florida observations were promising. Citrus trees growing in carbon-rich soil were larger, and the soil showed major differences in carbon and its ability to hold nutrients. Those findings helped show why biochar deserves further study in citrus production.

With its ability to improve soil, plant production and fruit yield, Wakefield Biochar products are suited for use in citrus groves. Wakefield Biochar is particularly effective on sandy soils, much like those that are found throughout Florida.