For details see the following USDA Pamphlet:
https://attra.ncat.org/attra-pub/organiccrop.htmlWhich contains the following:
Foliar Fertilization
Foliar fertilization or feeding entails the application — via spraying — of nutrients to plant leaves and stems and their absorption at those sites. It is not specifically an organic practice, though it is commonly used by many organic growers. The fertilizer materials used are typically soluble fish- and seaweed-based products, naturally chelated nutrients, humic acid extracts, and teas made from plants, dried blood, manure, guano, or compost.
At first glance, the use of foliar feeding appears contradictory to the organic notion that one feeds the soil to feed the plant. Organic growers rationalize the use of this approach on two points.
Foliar feeding is strictly supplemental fertilization; it is not used as a substitute for traditional soil building practices.
Foliar fertilization is understood to increase the production of root exudates, which stimulates biological activity in the rhizosphere (soil area adjacent to plant roots). The soil bio-life gets considerable benefit in this indirect way from foliar feeding.i.e. You can use aerial spraying and still be "Organic" under the USDA definition. In actual practice, even more can be done and still get your crop marked "Organic" by the USDA. The USDA's definition of "Organic" is so bad, that most true organic farmers are avoiding the whole certification process, as a cover for non-organic farmers to sell their products as Organic. One of the chief problems of the USDA is that its primary job is to promote Agriculture i.e. large corporate farms, to make money, protection of people who eat food is at best a poor secondary consideration.
Just pointing our that the term "Organic" has slowly become to mean nothing more then Farmers raising crops and thus may not even be restricted to "natural fertilizers" (Even the above regulation uses the term "The fertilizer materials used are typically..." NOT "Shall be", thus permits other fertilizers to be used if it is "natural", which is another non-defined term (i.e. can be anything that occurs "naturally" even if it is heavy processed afterward into what we call Fertilizer).