By Tacy Callies
In an effort to keep HLB-infected citrus trees productive, many Florida growers are turning to techniques aimed at improving soil health and nutrition. This was the subject of a recent seminar hosted by citrus grower Ed James and sponsored by Sand to Soil Services. More than 30 growers of citrus and other crops gathered at James’ grove in Howey-in-the-Hills to hear talks from industry experts on plant nutrition and soil health.
Photo: Tacy Callies
FOUNDATIONAL CONCEPTS
The first speaker was consultant Dane Terrill of Crop ices International. He discussed the five M’s of soil health: minerals, microbes, matter, moisture and management. “Carbon is the most important ingredient in any fertile soil,” he said.
Terrill addressed the topic of regenerative agriculture and defined it as “a system of farming principles and practices that increases biodiversity, enriches soil, improves watersheds and enhances ecosystem services.” He said the six core principles of regenerative agriculture are:
- Understanding the context of
your farm operation - Minimizing soil disturbance
- Maximizing crop diversity
- Keeping the soil covered
- Maintaining living roots year-round
- Integrating livestock
One way to improve soil health is cover crops. “We don’t need to study cover crops to know they work; they do,” said Terrill. “Cover crops add carbon to the soil. Biology rules the world, and carbon is the currency.”
MICROBES MATTER
The next speaker was RJ Rant, owner of Terraform Ag and Nutrilink Biosystems. Rant has advised growers across the country and designs products to meet their unique soil needs. His talk focused on ecosystem management strategies for improving soil health.
Rant said growers need to look at how all of their farm practices — including type of tillage, chemicals and fertilizer applied, and water quality — impact soil microbes. “Do not overapply nitrogen; it will crash the system,” he warned.
All the benefits of cover crops are not immediate, noted Rant. He said after four or five years, growers can expect to see an improved microbial balance in the soil that will result in regulation of pests and diseases, which will allow for reduced pesticide use. In his work with planting cover crops in potato fields, Rant said yields did not increase in the first year, but they showed incremental increases in the second and third years.
Rant also discussed the power of polyculture that cover crops can provide. “If all you are growing is citrus, soil microbes will be less diverse,” he explained. “If you feed microbes a more diverse diet, more will wake up and become active in the soil. More root biomass comes with more microbial diversity. Microbes release carbon dioxide for photosynthesis, which is the key to soil health.”
NUTRITION ADVICE
Joe Mullinax, plant pathologist for Denele Analytical Inc., provided expertise on soil testing and plant nutrition.
He offered growers the following advice:
• Potassium is critical for sugar levels.
• High sodium interferes with fertility.
• Too much nitrogen can lead to problems with pests.
• Look at what nutrients leave with the crop to determine what needs to be put back on.
• Total available nitrogen increases when soil microbes increase.
• It’s not about how much nitrogen you put out. It’s about putting out the right type at the right time.
REAL-WORLD RESULTS
After the seminar program, James led attendees on a tour of his grove and shared his experience with cover crops and other production practices. He said his production was at zero before he planted cover crops about 12 years ago. Production came back up four years ago to 300 boxes an acre but is now closer to 200 boxes an acre.
“I have backed off on cover cropping a little bit,” James said. “I’m fixing to dial it back in on the cover crops, balance the nutrients and get back up to 300 to 400 boxes an acre. The biggest problem for the crop production is there’s been zero added nitrogen all these years and very minimal micronutrients. I’m going to have to put some more micronutrients back in there to fill what’s deficient and possibly add a little bit of nitrogen, if I don’t get it from the cover crops this year. We’ll watch that according to tissue analysis.”
James is also applying some wood chips that break down as compost. The material, which comes from various types of trees that are trimmed near power lines, is provided to him at no cost from the city.
The grower said he only applies herbicide to a very narrow strip just a foot or so on either side of the tree trunks in order to maintain the integrity of the poly tubing and microjets. He also controls weeds by using an offset mower or cover crop roller underneath the trees. James uses paraquat; he has not applied glyphosate or any preemergent herbicide for 12 years.
When asked about using other chemicals in the grove, he reported he has used “no psyllid control, no pesticide, insecticide or fungicide in 10 to 12 years.”
James added that he has no fruit drop and is producing high-Brix fruit. “My Hamlins are still getting 10.7 to 11 Brix. My goal is to improve the soil biology to get that Brix level higher.”
“Growers need to focus on biology. It drives everything on the tree, in the tree and in the soil,” concluded Brad Turner, citrus grower and owner of Sand to Soil Services. “You must have sufficient carbon in the soil to feed and grow that microbial workforce.”
Jack Scarborough, one of the citrus growers in attendance, said he learned a lot from the event, especially in the area of what inputs are best for soil health. “In all types of agriculture, if we are able to lower our inputs, that’s going to help our bottom line,” he said.