“The conventional orchard today is planted on 15-by-25 foot spacing; the modern orchard is 10-by-20 and the high density orchard we are talking about with [advanced production systems] is 8-by-15. So the system is taking us from about 100 trees an acre to 363 trees per acre,” Castle says.
In addition, growers using advanced production systems apply imidacloprid to control the Asian citrus psyllid—the main vector of citrus greening—and reduce disease losses the first three years. From there, dense spacing should help mitigate tree losses from greening, Castle says. Spyke says that since the trees for the trial were planted in November 2006, the company has only lost 10 out of 1,400 trees to greening. “So far, that is pretty good,” he says.
The hydroponic system within the advanced production system uses fully automated drip irrigation and fertigation systems to supply water and macronutrients, based on the trees’ growth stages. In a true hydroponic system, roots are maintained in a water and nutrient solution in a closed loop system.
The goal is to produce exceptional yields by the time the orchard is 3 years old and turn a profit by the time trees are no more than 5 years old, Castle says. By the time trees are 8 years old, growers would theoretically recover the cost of investment to set up the initial system. With the high cost of nursery trees, he says it’s imperative that growers manage the two systems to meet the eight-year financial targets if they want them to be economically viable.
“It’s a big investment in trees alone,” he says. “The drip system, we believe, will be less expensive in the end because it requires a smaller pump… and uses water more efficiently. And ag will also come out on the short stick for water, so this drip system offers distinct advantages by virtue of the way it’s managed.”