Growing Citrus With Soil Health in Mind

Daniel CooperCover Crops, Georgia, Soil Health

Trees grown with regenerative practices grow more slowly than conventional practices but are robust.
Photos courtesy of Herb Young

Herb Young enjoyed a 40-year career in the agricultural chemical industry, starting as a technical service representative and eventually becoming a product manager. During those years, he worked on various specialty crops across the country. About 25 years of his career was spent in field research roles. So, experimentation with crops and growing practices comes naturally to Young. He has applied what he has learned to his new venture in retirement — growing citrus. We asked Young about his planting and his focus on regenerative practices.

In retirement, Herb Young is chasing a passion to learn more about regenerative agriculture in citrus production.
Tell us about your citrus planting.

YOUNG: When I retired, I decided to become a citrus grower and joined the ranks of about 150 citrus farmers in Georgia. I’ve got a relatively small piece of land, just 6 acres. I read about Florida growers experimenting with high-density planting as a way to combat HLB. So, I designed my grove with high-density planting using dwarf rootstocks. With the fresh fruit market expanding rapidly with satsumas, I decided to grow a variety of citrus, including Cara Cara, Page mandarins, Honeybells, grapefruit, blood oranges and Shiranui. Unfortunately, my trees are only three years old and were hit hard by the 2022 freeze. I’m also trying to grow limes in a hoophouse. I’ve learned that lemons may not be feasible, and grapefruit will always be risky in Georgia due to the cold snaps. I’ve installed microjets under every tree for frost protection and fertigation. Georgia’s consistently colder weather allows our trees to get closer to dormancy than Florida.

Have you encountered psyllids and HLB in your trees yet?

YOUNG: Fortunately, the psyllid hasn’t made its way to this part of Georgia yet. We’re not exactly sure why, but we’re in a grace period where HLB hasn’t affected us. With a mutation in the psyllid, I expect it to head north eventually.

What drew you to soil health and regenerative practices?

YOUNG: After spending my entire career developing pesticides, I began to explore the idea of growing organically as a potential financial incentive. With my experience as a plant pathologist, I had the opportunity to test some organic alternatives. As I delved into the literature, I discovered that there had been remarkable advances in soil microbiome research over the last decade. This captivated me. The more I researched, the more engrossed I became, and my passion for growing regeneratively was born. Now, whenever I find a production practice that isn’t clear from a regenerative point of view, I set up a trial. My grove is like a living laboratory with research plots everywhere.

The use of cover crops and microbial applications have promoted strong root systems in the citrus trees.
Describe some of your regenerative practices.

YOUNG: The key is creating an environment where microbes can thrive and “regenerate” the soil. This means having cover crops year-round and avoiding tillage. The exudates from these cover crops nourish the microbes in the soil. I plant 10 different species of cover crops in the spring and fall, including grasses, legumes and crucifers. The cover crops are mowed into the tree row for mulch. I inoculate with beneficial microbes, both bacteria and fungi, and much of my fertility management is aimed at feeding these microbes. I regularly pull leaf samples for sap analysis and respond with targeted organic fertility treatments. I alternate between irrigation-injected nutrition and foliar sprays.

Have you seen positive results from these practices?

YOUNG: The changes have been remarkable, albeit gradual. Most notably, the soil has transformed. I use a penetrometer to measure soil porosity. In the areas where I’ve implemented cover crops and microbes for three years, the device easily goes 30 to 36 inches deep in the tree rows, compared to just 3 to 4 inches in the alleys and middles. The ground has even risen due to the repeated mulching with cover crops, and it feels spongy. Water penetration has improved significantly.

I received a grant from Biome Makers to measure soil microbial DNA in a trial (135 trees) comparing conventional vs. regenerative methods. In the first season, the number of microbe species in the regenerative treatment jumped from 680 to 1,082, while the conventional treatment increased by just 109 species. Over time, the conventional rows lost diversity due to bare-ground Roundup sprays and became dominated by a single fungus (89%). In contrast, my regenerative rows maintained diverse microbial communities supporting the trees. This diversity is key to regenerative effectiveness. We were taught to consider all fungi as pathogens. But in a balanced soil ecosystem, most are beneficial.

Each circle in the diagram represents a fungal species, with size indicating quantity.

My goal for the farm is to prove that these regenerative practices result in nutrient-dense fruit. It has to be significant enough to justify the effort. This year, I harvested my first fruit, so I’m comparing them with conventionally grown fruit of the same variety from other farms. Muhammad Shahid from the University of Florida Institute of Food and Agricultural Sciences North Florida Research and Education Center in Quincy is helping analyze two varieties, Page mandarin and Pink Frost grapefruit. Visual and taste differences are apparent, and I hope to see differences in nutrient content, too, including flavonoids, carotenoids and vitamins (A, B complex, C, thiamin and riboflavin).

Fruit grown with regenerative practices (right) has a deeper color than conventionally grown fruit.

For the grapefruit, I set up a four-person blind taste panel to get objective impressions. Responses from the conventional Pink Frost included: juicy, tender, mild, light, pleasant and dissolves quickly. Comments for my regenerative fruit included: wow, crisper, more in depth, bolder, complex, deeper, hits all parts of your mouth, lingering and quicker. I think that was a good description of nutrient-density. Lab results will tell the story.

Organic matter has increased in the regenerative grove. I’ve gone from 1.68% to 1.84%. Both microbial life and tree health can be impacted.

I’m also conducting a U.S. Department of Agriculture-supported trial to compare different composts and compost tea. It involves lots of measuring: canopy size, percent flush, trunk diameter and microBIOMETER microbial ratios. I hope to see some differences this season.

Other trials have included citrus leafminer, Chilean nitrate, EnSoil Algae, mulching and organic fire ant control.

How important is patience when pursuing regenerative practices?
Herb Young is experimenting with growing cold-sensitive citrus under hoop houses for freeze protection.

YOUNG: That’s the biggest challenge. Regenerative trees don’t grow as fast. In my comparison trial, they are less than half the size of conventionally grown trees. Despite giving my regenerative grove intense organic fertilization every two weeks, trees remain smaller. I suspect cover crops growing right up to the tree trunk may be the cause. I’m still trying to be certain why there’s such a significant growth difference. It’s potentially the biggest limitation to growing regeneratively.

Is there anything else you’d like to add?

YOUNG: After spending 40 years in the conventional or “industrial” agricultural system, developing and promoting pesticides, I’m amazed to discover that this dynamic ecosystem can exist in the soil under a crop and support its health. It almost feels like the best-kept secret. I’m on a mission to either prove that it’s financially viable to have trees and microbes coexist harmoniously or show that it’s not. Finding answers is satisfying, but there must be a financial return as well. Regardless, I’m having the time of my life.

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Frank Giles


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