an agricultural enterprise for the production of hothouse crops and the seedlings of vegetable and flowering plants. A hothouse complex consists of primary and auxiliary facilities united in a single technological process. The basic elements are numerous multiple-unit, single-unit, and plastic-covered hothouses. Auxiliary facilities include a heating system; a retail department with a refrigerator; storehouses for planting material (tubers, bulbs), inorganic fertilizers, and pesticides (toxic chemicals); a tool shed; a garage; workshops; administrative offices; and recreational areas. Some hothouse complexes also have lightproof rooms for raising mushrooms.
Hothouse complexes are usually established close to a large city or industrial center. In the USSR the area allotted for hothouse complexes is 3–3.5 hectares (ha) per ha of single-unit hothouses and 2–2.5 ha per ha of multiple-unit hothouses. Extra land is allotted for possible future expansion. Hothouses must be situated far enough apart from one another so as to allow optimum ventilation and to minimize shading. Single-unit hothouses situated south of 55° N lat. should be no less than 3.5 m apart; those located farther north should be as much as 5–7 m apart. Multiple-unit hothouses should be spaced 10–15 m apart. The auxiliary structures are placed in the northern part of the complex; the hothouses are placed in the northwestern section, on the most elevated site. To the south of the hothouses are placed early, middle, and late hotbeds, respectively. Heated ground must be located south of the hotbeds and along the periphery of the area. Alongside the hothouses permanent areas are assigned for storing soil mixtures and organic fertilizers. Usually an area of open ground is provided for growing planting material.
The best-known hothouse complexes in the USSR are the Moskovskii near Moscow (occupying 54 ha) and the Leningrad-skii near Leningrad (42 ha), as well as the complexes in Kazan (24 ha), Vladimir (24 ha), Voronezh (12 ha), Kishinev (12 ha), Lipetsk (6 ha), and Penza (6 ha).
Capital investment for construction of modern hothouse complexes, including roads and communication systems, is about 90 rubles per sq m of interior hothouse space. Hothouse crops grown in the south cost less to produce than those grown in the central and northern regions of the USSR. Production expenses in the south are 15–20 percent less than in the central zone and 40–50 percent less than in the north. For this reason, to supplement hothouse complexes and hothouse farms in northern latitudes, complexes are being built in the Northern Caucasus, Middle Asia, and other southern regions; the produce grown at these enterprises is sent to industrial centers of the Central European USSR, the North, the Urals, and Siberia.
The standard designs for hothouse complexes in the USSR are technically equal to foreign ones. The hothouses have the capacity to regulate automatically the microclimate and the watering and feeding of plants. The large area and wide spacing permit maximum mechanization of the principal production processes. Great economic efficiency has characterized the leading hothouse complexes of the USSR (Moskovskii, Leningradskii, Simfero-pol’skii, and Kislovodskii). Yields are 33 kg of cucumbers per sq m and 12–20 kg of tomatoes. The labor expenditure per quintal of produce is five to nine man-hours. Labor productivity is two or three times greater than that of small hothouse farms; in addition, production costs are lower. The construction costs for a hothouse complex are completely recovered in four or five years.
Hothouse complexes are marked by the most advanced forms of labor organization. They have permanent specialized production brigades and units; each brigade maintains 12,000–25,000 sq m. The work is organized on the principles of cost accounting and is performed in accordance with the generally accepted technology for growing each type of plant. Special units under the supervision of a plant-protection agronomist are responsible for the control of plant pests and diseases; biological and other methods of control are used. There also are teams of apiculturists and independent subdivisions for technical services. Hothouse combines also have research laboratories. The organization of production associations (Vesna in Moscow, Leto in Leningrad) has promoted further specialization of hothouse complexes.
In Bulgaria, Rumania, Poland, the Netherlands, Great Britain, the USA, Japan, Denmark, and other countries, large efficient hothouse complexes have been established for the commercial production of vegetables and flowers, as well as of seedlings for subsequent planting in the open ground. The principal processes involved in raising vegetables and creating a microclimate are automated. An increase in the number of glass-enclosed hothouses has been paralleled by a significant increase in the number of plastic-covered ones. In some countries, including the USA and Canada, the area occupied by plastic-covered structures is two or three times greater than that occupied by glass-enclosed ones.
In Bulgaria several hothouse complexes with areas ranging from 24 to 75 ha have been established. The largest complex (Pazardzhik) raises its principal crops—tomatoes and cucumbers—in one rotation from October through June; seedlings are grown in August and September. In Rumania hothouse complexes occupying areas from 100 to 240 ha have been built, principally near large cities and industrial centers, such as Bucharest and Ploieşti. The principal hothouse crops are tomatoes, peppers, and flowers. Sixty to 70 percent of the crop is for export. At large hothouse complexes two-thirds of the hothouses are used for growing flowers and one-third for growing vegetables. In Poland a hothouse complex with an area of 20 ha has been established in Silesia. The principal crop is tomatoes; the hothouses are arched and multiple-unit.
The Netherlands ranks first in the world in area occupied by hothouses (more than 5,000 ha in 1971), and in hothouse production. Most of the hothouses are multiple-unit. More than 80 percent of the vegetables are exported, accounting for about 25 percent of the country’s total agricultural export. Hothouse farms have attained a high level of labor productivity: one worker is responsible for 1,500–2,000 sq m under cucumber cultivation or 3,000–3,500 sq m under tomato cultivation. One of the factors raising labor productivity is the cultivation of long-fruited parthe-nocarpous cucumber hybrids and high-yielding tomato hybrids.
Great Britain occupies second place among the member countries of the European Economic Community in area of glass-enclosed hothouses. In 1971 glass-enclosed hothouses occupied 2,395 ha, and plastic-covered hothouses 720 ha. The principal crops are tomatoes, cucumbers, lettuce, and flowers. Some farms are practicing year-round tomato cultivation, and these efforts look promising. The average yield of tomatoes is about 18 kg per sq m.
In the USA commercial hothouse complexes are concentrated in the Southeast; the principal crops are tomatoes (occupying 63 percent of the area), lettuce (26 percent), and cucumbers (3.5 percent). In Japan about 4,000 ha of plastic-covered hothouses and tunnels are used from October through June, principally for the raising of vegetables. The principal hothouse crops are watermelons, eggplants, peppers, muskmelons, tomatoes, and pumpkins.
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G. V. BOOS