Agricultural Aviation

that branch of aviation which uses airplanes and helicopters for a variety of tasks in agriculture. Agricultural aviation is employed to protect plants, control weeds, destroy undesirable vegetation, remove the leaves of cotton and other crops prior to harvest, apply mineral fertilizers, and sow grass seed. There are several advantages of aerial over ground methods. The work time is shortened because of the airplane’s great speed (up to 160 km/hour) and broad sweep (up to 60 m when dusting and spraying and up to 30 m when spreading mineral fertilizers). The expenditure of labor is lower, and there is less consumption of toxic chemicals and fertilizers. The maneuverability of planes and helicopters makes it possible to treat large tracts of land and permits quick shifts from one tract to another. Agricultural aviation makes it possible to work relatively inaccessible plots, and its use is not dependent on the condition of the soil surface. There is no mechanical injury to the plants or compaction of the soil. A shortcoming of agricultural aviation is its dependence on weather conditions.

In 1973 aerial chemical treatment was used on more than 86.8 million hectares (ha) of farmland and forests in the USSR. The An-2, An-2m, and Iak-12 airplanes and the Mi-1, Mi-2, Ka-26, and Ka-15 helicopters are used in agricultural aviation in the USSR. They are equipped with special devices to spray liquid pesticides, dust powders, and spread mineral fertilizers and poison bait, and sow seeds.

Plant pests and diseases are controlled by spraying or dusting pesticides or poison bait in parallel strips from a height of 5 to 10 m. Powdered pesticides are used for dusting; the rate of consumption is 10–40 kg/ha. Spraying is done with the same pesticides as on the ground but at higher concentrations; the rate of consumption is approximately 500 liters (l) of active principle per ha. Mist spraying is highly effective, requires less liquid (25 l/ha), increases labor productivity, and lowers costs. Crops on mountain slopes are treated from helicopters. The particular aerodynamics of helicopters make it possible to work at low flying speeds and apply pesticides to the underside of leaves and in the lower stratum of tree crowns. Spraying and dusting are usually done in the morning and evening. Poison bait is also scattered during the day.

Weeds among cereal grain crops, corn, millet, and flax are controlled by spraying aqueous solutions or emulsions of herbicides from a height of 5–6 m in spring at the times specified by agricultural regulations. The herbicides are expended at the rate of 0.3–1.2 kg of active principle per ha. Liquid herbicides are expended at the rate of 25–50 l/ha for cereals and corn and 100–150 l/ha for flax.

Undesirable trees and shrubs are destroyed by spraying with herbicides in spring before the buds open, by spraying the leafy shoots in the summer, or by spraying in the fall after the leaves have fallen. The liquid is expended at the rate of 25–100 l/ha. The spraying is repeated every other year to ensure the complete destruction of the trees.

Mineral fertilizers are applied mainly as a top dressing during the growing season. At such times, ground machines cannot be used because the soil is too wet or there is a danger that the wheels of the machines will damage the plants. Uniform spreading of granulated and powdered mineral fertilizers ensures that the top dressing will be highly effective, and the high efficiency of airplanes makes it possible to apply the fertilizers during the most suitable periods. Powdered fertilizers are scattered from a height of 10–20 m, and granulated fertilizers, from a height of 30–50 m.

Defoliation of cotton plants and some other crops is accomplished by dusting or spraying with defoliants before machine harvesting. The defoliants hasten the formation of an abcission layer on the petioles and subsequent leaf fall.

Helicopters moving at low speeds at altitudes of 5 to 10 m are used to promote additional pollination of flowering plants, wind-pollinated crops, and crops that do not attract many insects, such as grape vines and corn. The helicopters drive the air downward at an approximate angle of 45° with a velocity of 5–10 m/sec, thus ensuring the transfer of pollen from flower to flower. The flights are made in the morning in warm, dry weather, when there is no dew and the flowers are fully opened.

In the USSR aerial sowing is used for coniferous trees in the central regions, for saxaul in the desert and semidesert regions, and for grasses in various other regions.

Agricultural aerial work is done by special aviation units of the Ministry of Civil Aviation of the USSR by agreement with agricultural organizations or individual farms. The uses of agricultural aviation abroad are similar.