Want high benefits? The greenhouse film choice needs to be cautious
With the continuous development of the facility agricultural gardening industry, the film greenhouse has gradually increased its market share with its cost -effective characteristics. In the face of a wide range of greenhouses in the market, how to choose is one of the problems facing the growers. This article mainly describes the choice of greenhouse covering membranes in production to readers.
Greenhouse covering membrane classification
In terms of technology, the greenhouse covering membrane has three layers of common crowding, five layers of crowding, and nominal seven layers. In terms of thickness, there are eight wires (1 wire = 0.01 mm) (the “wire” is called “Dao” in the Northeast region). In terms of life, there is one year, two years, and many years of membranes. From the name, there are PO film, PE film, EVA film, and bubble film. In terms of function, there are longevity, no drops (anti -flow drops), fog (also known as fog), dust, scattering (also known as scattering), cover white (also known as “milky white”), insulation, turning light, turning light, turning, and turning, and turning light, turning light, turning, and turning light, turning light, turning, and turning, and turning light, turning, Incorcped and spectral selection of filtration, users usually do not understand what functions can these functions bring to crop growth when actual use. In order to facilitate the choice, the growers should focus on the income and let the choice direction start with the “income” goal. There are five ways to achieve income: ① high output; ② good selling (such as color, uniformity, and face value); ③ exclusive patent (such as a certain variety of flowers); (The time difference between fruits and vegetables in the morning or late marketing, and the requirements of special significance of flowers are strict). The above five methods of income are often not realized at the same time. After the growers determine the main income, the crop can be determined that the crop’s growth environment and conditions needed to be required for this income. Starting from the requirements of the environment and conditions, you can locate the film you want to choose.
Factors affecting greenhouse covering membrane performance
Keep the insulation
The heat preservation function of the film refers to the heat absorbed by all objects including crops in the greenhouse during the autumn and winter in autumn and winter. The heat caused by indoor and outdoor temperature differences at night is flowing from high to low, and the thermal energy of infrared forms in the form of infrared is in the shed. When the external radiation scattering is scattered, the greenhouse film blocked by an infrared barrier barrier is added, and it can continue to be maintained in the greenhouse to minimize the loss of calories and reduce the temperature in the greenhouse. This is an active regulation based on the principle of blocking infrared radiation, which can effectively avoid sudden changes in the temperature indoor temperature, thereby avoiding the decrease in crop frostbite and being suppressed. It is worth noting that insulation is not heating, it is to minimize the loss of your own storage heat, rather than increasing calories and increased temperatures like heating equipment. Ordinary membranes without infrared barriers also have insulation functions, but it is just a passive implementation that prevents the exchange of hot and cold air. It is also very short.
The principle diagram of the insulation membrane regulation
The cooling of the greenhouse film is a limited role that played a certain percentage of whitening agent. The application range is special. In order to ensure the normal photosynthetic effect of the crop, it is usually installed in the greenhouse facade and special orientation. It is suitable for the overall of crops caused by strong radiation climate and strong western sun in summer. Plantors can choose the level of whiteness according to their own situation, such as 40%or 60%of the cover white. This membrane cannot be equated with the shading net. The temperature of the membrane is very limited, and it can only relieve strong sun exposure in part and stage, and cannot completely replace the shading net.
The main reason for the humidity of the greenhouse for the film is the temperature difference between the morning and evening in the autumn and winter. The greenhouse without ground membranes or ground cloth has a heavy moisture with the greenhouse or the ground cloth. Condensation and fog on the surface of the roof. If not controlled by control, the humidity of the crop area is heavier, resulting in the disease. The droplet and fog function of the greenhouse can avoid the formation of fog. At the same time, condensate water droplets pasted on the surface of the membrane converge into a large water film and form an orderly export in the direction of the water flow along the top of the top. The severe moisture caused by the greenhouse, thereby reducing the occurrence and spread of pests and insect pests, and also increased the light transmission of the membrane. The southern room where the condensed water in the south can choose a shed film without flowing droplets. For double -layer membrane greenhouses, the top or outer layer can use a membrane with a normal long life without flowing droplets. The droplet function membrane is installed in the greenhouse layer. The light transmission is better and can save costs. The adjustment of the film’s humidity is to interfere with the direction of fog and guide condensate water, so that the humidity in the greenhouse is as far away from the crops as much as possible, which is not the same as the concept of dehumidification, but it is very effective.
Ordinary film without streamlined
Dripping -free film
Light contains 3 contents, which are light, light distribution and light. The amount of light refers to the total amount of light entering the greenhouse. Light distribution refers to the radiation angle of light entering the greenhouse. What are the main spectral bands after light entering the greenhouse. As long as the amount of light is not covered with white film, the light transmission rate of all types of greenhouse sheds is completely sufficient for the photosynthetic effect of the greenhouse crops, all around 90%. The distribution of light in the greenhouse is the proportion of direct light and scattered light. Too many direct light will bring more shadows to cause uneven crop growth. The appropriate scattered light makes the light distribution in the greenhouse more uniform, which is particularly beneficial to the rattan crops. The crop blade is better open and closer when breathing. In addition, in areas with strong solar radiation, scattered light can also reduce the strength of light, soften the light in the greenhouse, and play a certain protective role in the crop. It looks less transparent scattering function membrane does not mean low light transmission. The total light transmittance of incident light is affected by the form of light distribution -scattering or direct influence is very small, which can be ignored.
Shadow situation under different film
Before entering the greenhouse, the light under the normal clear sky is full band (the atmosphere will absorb part of the ultraviolet rays). After entering the greenhouse, the composition of the band of the spectrum changes. If you do not intervene, the useful optical quality cannot play its greatest role, and the growth performance of the crop cannot achieve the purpose of the grower. The additives in the greenhouse can make the special light quality or the light wave segment that enters the greenhouse to make useful intervention and regulation to the crop growth.
Portal composition of solar radiation
The ultraviolet band will deepen or blackened the color of the edges of the petals of flowers such as monochrome roses, and reduce the selling phase and price, but on the other hand, the color of flowers such as two -color roses is more bright and the taste of fruits and vegetables is better. In addition, the short band is the visual wave band of the throbbing paveo aphids. If you want to prevent insects, you need to consider whether the crop needs is needed. At the same time, this part of the band is also required by polishing bees. It will be greatly reduced. In the same way, the red and orange light section usually stimulates the growth of crops, while Blu -ray generally produces inhibitory effects. This affects the time of the crop. Of course, the impact on different crops will also be different. Specifically, the planting person needs to be comprehensively considered according to the crop and the local environment at that time. The contradiction function must not be strengthened at the same time in the same membrane product. Functional choice. Because of the particularity of the light band, the film of this function and the general film cannot be distinguished from the naked eye. Need a special instrument. When choosing a user, the manufacturer can provide the corresponding indicator data. In addition, the efficiency of the spectrum filtration of this functional membrane will not weaken with the use time of the membrane.
The strength index of the greenhouse covering the membrane usually has stretching strength, tearing strength, and impact force. Stretch intensity: In actual application, it is related to the installation of the membrane. The intensity required to stretch the membrane to break is usually passed by all manufacturers. This is the minimum standard for ensuring that the greenhouse can be tightened and flat when installing. Another practical significance of this indicator is also related to wind load, snow load (or pressure accumulation pressure). The torn intensity is more reflected in the cracks of a small section of the person in the shed film, and the forces needed to be torn in the relevant direction, such as the folding line of the shed film. Anti -impact force refers to the impact caused by the instantaneous external force to break the membrane. The actual application is reflected in the shock and hail above the shed film, and the sudden stamp suddenly staged in accidentally during daily operations.
There are two main factors that affect the life of the greenhouse. Light aging is plastic products (including greenhouses). Undear exposure to the sun will absorb UV in large quantities, and therefore causes the polymer molecular structure of plastic products to be destroyed, which causes life to decay. Mechanical properties, tensile stretching, tear resistance, and impact resistance decreased, that is, aging or optical oxidation. The heat aging is broken due to the excessive temperature caused by the thin film molecular chain, which accelerates the reduction of mechanical stress. The other is chemical aging, but this is not natural aging. Chemicals containing sulfur -containing are often used to sterilize insects, but this also greatly shortens the normal service life of the membrane. Different standard products of different manufacturers have certain anti -sulfurizing indicators. More manufacturers are usually in this indicator. It is sufficient for the normal use of users. For example, sulfur/mol’s sulfur/mol’s sulfur and 150 umol/mol chlorine can ensure that the normal service life of the membrane is within the warranty period.
The greenhouse film that has been used for 8 years
The life insurance period given by all greenhouse membranes is based on the light aging and thermal aging in the natural environment during the normal application period of the membrane in the natural environment after the installation coverage and the coverage of the coverage. The intensity of light radiation and thermal radiation, of course, the surrounding environment is also an important factor that the growers should consider if there are related chemical plants and coal factories. For planters, when choosing greenhouse coverage, it is necessary to consider the local environment and the greenhouse structure. Of course, the carefulness and protection in practical applications (such as avoiding direct contact with metal, increasing the shading net, reducing the use of chemicals, etc.) The life of the membrane will be extended.
In the production, the film is added to the outer layer to add an anti -static additive, so that the outer layer of the membrane can minimize the extent of the dry air that is adsorbed on the outer surface of the greenhouse, which improves the self -cleaning of the outer surface of the membrane, thereby reducing the outside of the membrane. The accumulation of dust also reduces the opportunity to produce moss and algae during the appropriate temperature and humidity. For areas where the climate is relatively dry and dry, the role of this function can be better played. But the film with a dustproof function can completely avoid the production of moss. Moss is easily formed when the air circulation, suitable temperature and high humidity, and whether it is in the inside or outside of the membrane, on the inner and outer shading network, or even on the polyester board, and on the skeleton, the places that can be attached to the moss spores will produce Once it is generated, it is very easy to connect and it is difficult to eradicate. Therefore, even after many years of use, even if the mechanical strength such as tensile stretching is still very good, it has to be new because of too much moss to reduce the light transmission rate, and the crops cannot grow normally. Therefore, the ventilation in the shed and humidity control are very critical factor. Many manufacturers are developing for greenhouses that prevent moss, but as of now, there are no mature products that can be successfully listed. The approach of foreign countries is to clean the membrane regularly. In this way, the duration of the membrane can be synchronized with the strength of the membrane, which is often twice or more than the manufacturer’s written warranty period.
When considering the service life of the membrane, the user is often linked to the thickness, and the thickness will increase the mechanical strength of the membrane. However, for the impact of light aging and thermal aging on life, it is mainly related to the corresponding antioxidant stabilizer. At the same time, thickness is the most important factor affecting the cost of the membrane. Therefore, the user must consider the comprehensive cost in the choice of membrane thickness.
Generally speaking, the thickness of the choice of membrane often depends on the type of greenhouse. The equipment and facilities are relatively complete, and the high -top large -scale large -scale greenhouses with high tops are often high. The value of the crops growing is often high. The difficulty of changing the membrane once and the high labor costs. A longer membrane. The relatively simple northern sunlight greenhouse or ordinary spring and autumn sheds. The relatively easy and planted crop value of sheds is limited, and relatively thin membranes are usually selected.