Some growers are already mapping soil types and trying to remedy inconsistencies, said Joby Sherrod, a research and development manager with DUDA, one of the state’s largest agricultural producers.

“The striving for uniformity is one of the biggest issues the industry deals with,” said Sherrod, in LaBelle. “When you examine the best blocks of trees, you find those are some of the most uniform blocks in terms of soil condition.”

DUDA grows about 8,000 acres of citrus in Florida, all in Hendry County. The general topography of the land is called flatwoods, and it has greater soil variability than the central ridge areas farther north in the peninsula.

“Even a bad soil, if it’s uniform, is better than highly variable soil, because you can manage it,” he said.

Mann said a practice called site-specific management can address scattered soil nutrient deficiencies, using variable-rate micronutrient spraying and granular fertilization guided by GPS coordinates.

Sherrod described how his company employs site-specific management:

First, personnel test the soil’s electrical conductivity and use the data to map the grove, then divide it into management zones. Next, they choose target locations for soil sampling, take samples and analyze them for various properties.

“Then we start to drive our management practices where we can,” he said.

One property Sherrod tracks closely is soil pH. The company can raise pH in some areas by applying lime, or reduce pH in others by applying sulfur, he said.

Schumann believes soil variability might play a role in the spread of citrus greening, a disease threatening the industry nationwide.

“Soil variability can stress trees, and stress might make them more vulnerable to infection,” he said.