In 2009, frequent meteorological disasters such as wind blizzards, heavy snowfall, and continuous low temperatures caused severe losses to the vegetable production in our province. Recently, Hebei Agricultural Technology Extension Station formulated the “Guiding Opinions on Optimizing the Structure of Vegetable Production Facilities†to comprehensively improve the comprehensive disaster-resistance production capacity of vegetable facilities in our province and promote the sustainable and steady development of the vegetable industry.
I. Status of the production of vegetable in the province
In recent years, vegetable facilities in our province have continued to grow. In 2009, the sown area reached 802 million mu, including about 5 million mu of greenhouse area, which has played an important role in promoting the structural adjustment of the vegetable industry, ensuring winter-spring market supply, and increasing farmers' income. Contributions. However, vegetable production in our province still suffers from different standards for facilities, aging structures, poor resilience, and lagging technical equipment. It is difficult to withstand the frequent occurrence of bad weather, heavy snowfall, persistent low temperatures, and even bad weather. The development of facilities vegetables. Only the historically rare Blizzard experienced in Central and South China in November 2009 caused 865,000 mu of vegetables in the province to be affected, including 12.5 million mu of ground-breaking vegetables and direct economic losses of 800 million yuan. Therefore, optimizing the structure of vegetable production facilities is imminent.
Second, structural optimization content
According to the cold and windy conditions in our province, the large winds in the south-central region, the overcast days in the south-central region, and the concentration of rain in the summer, according to the principle of good temperature and light performance, energy saving, cost-saving, rationality, sturdiness, and practicality, the solar greenhouse in our province is now In the spring and autumn, the plastic arch structure optimization provides the following technical guidance.
1. Solar greenhouse structure
(1) The use of steel pipe and round steel structure skeleton, welding joints to be strictly supported; or using cement pillars, bamboo + bamboo raft arch structure, can not use composite material skeleton or pure bamboo wood skeleton.
(2) The span should be 7 to 8 meters, and the maximum should not exceed 10 meters. The ridge height should reach 3.8 to 4 meters, and the high-to-high ratio of 1:2 to 2.2 is appropriate.
(3) In the room, 2 to 4 rows of columns are set according to the skeleton material. The pillars of the steel and round steel skeletons can be appropriately reduced, but there is a row of posts at the highest point of the rear slope.
(4) The back wall is earth wall, the narrowest part is not less than 1.5 meters; the back wall is brick wall, thickness is 60-65 centimeters, inside and outside 2 to 4 brick walls, plus insulation board in the middle. The height of the back wall should reach 3.3 to 3.5 meters, and increase the front crown.
(5) The back slope length is 1.4-1.5 meters, and the thickness is 50-70 cm. It is light, strong, waterproof and heat-insulating material.
(6) The greenhouse should be semi-underground cultivation, subsidence of 50 to 80 cm to improve the insulation performance.
(7) Insulation materials for the front slope of greenhouses are replaced by conditional insulation instead of grasshoppers. If grasshoppers are used, they must be covered with a high quality, watertight plastic film or other tarpaulin.
(8) The greenhouse shall be provided with a fixed beam or base of the cement brick structure under the front foot to increase the overall stability of the greenhouse frame.
2. Plastic arch shed excellent structure
(1) Steel skeletons shall be used to ensure that the joints shall be tightly supported by welding; if concrete pillars or bamboo pieces + bamboo rafts are adopted, the concrete part shall be reinforced in the ground. Composite skeletons cannot be used.
(2) The sheds are preferably designed to be long and wide in the north and south and east and west. The span is controlled at 8 to 10 meters, the ridge height is 2.2 to 2.5 meters, and the maximum is no more than 3 meters. The high-to-high ratio is 0.18 to 0.3.
(3) The indoor installation column is based on material, 5-6 rows of bamboo structure, and 0-3 rows of steel structure. Increase the height of the arch above the arch, it is best to set the top of the wind vents.
Third, improve the overall resilience of the shed
While optimizing the structure of the greenhouse facilities, various localities must also pay attention to improving the overall stability of the facilities and the resistance to snow, wind, rain, pressure, and pull, in terms of design, material selection, and construction, in accordance with local conditions and climate characteristics. Comprehensive disaster resilience. The construction of arches and beams in the greenhouse is preferably made of steel bars and cement arches. The cement quality must be up to the standard, and the rear roof is preferably made of prefabricated cement. In the construction of bamboo structures in greenhouses, the quality of selected bamboo rafts and bamboo strips must be better. The pillars are preferably cement pillars, and the steel wire ropes used for horizontal and horizontal pulling are used. The shed film should choose PVC or EVA high-efficiency drop-free film produced by regular manufacturers. When constructing the welded steel frame in the shed, the connecting points should avoid the tensioned area and the joints should be welded firmly. The key parts of the shed roof should be connected with triangular reinforcements.
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