Many home citrus growers will vouch for the taste and quality of organically grown fruit. But there are far more benefits to growing citrus trees organically than just flavor. Organic practices are designed to benefit the health of the soil, the environment and the people who eat the citrus. While citrus trees can be nutritionally demanding, using a variety of organic fertilizers will provide the citrus orchard a complete nutrition profile.
Solid organic fertilizers include manure, coffee grounds, spent beer brewing ingredients and well-rotted compost. Compost and manure are best incorporated into the soil before planting the trees, but can be top-dressed during the growing season along with the spent brewing ingredients and coffee grounds. Fish emulsion, liquefied kelp and compost tea are liquid fertilizers that give the citrus trees a quick nutritional boost.
Most organic fertilizers used on citrus orchards are mild soil acidifiers, which helps adjust soil pH in the citrus tree's favor. The effects are not as immediate as with chemical fertilizers, but instead rely on planning and integrating multiple fertilization methods, building the soil fertility and organic complexity over time. Organic fertilizers also encourage microbe activity in the soil. The goal is to balance the microbes so that a single malicious microbe, such as those that cause citrus foot rot, have stiff competition to overcome before they can damage your citrus tree.
Commercial citrus production does not often rely on organic methods, because the producers rely on bumper crops produced as soon and as often as possible. But it is not necessary to use chemical fertilizers to get a decent crop, especially on home-grown citrus. Using organic fertilizers, building the soil nutrition, avoiding harsh pesticides and inter-cropping with beneficial plants is more than sufficient for producing flavorful, toxin-free citrus fruits.
Avoiding chemical fertilizers reduces the amount of toxic fertilizer runoff that seeps into groundwater and waterways. Organic fertilizers are also friendly to predatory insects and microbes, and can be used in conjunction with organic pest control practices. While chemical fertilizers encourage citrus to grow foliage and fruit quickly, this puts a lot of stress on the tree. Organic fertilizers allow the tree to grow closer to its own pace, so that it can manage its overall health in a balanced way.
Permaculturalists plant small legume trees or large legume shrubs in their orchards. They are planted close enough to the citrus to allow the roots to intermingle. Every two to three months, they cut back the legume by a third. All cuttings are dropped around the base of the citrus trees for mulch and soil fertility. The legumes react by shedding roots, and the nitrogen they've fixed is released into the soil in a form citrus can readily absorb. Chickens or other fowl roam in the orchard to scratch and aerate the soil while their droppings fertilize the orchard.