First, the classification of agricultural film
Agricultural film can be divided into shed film and plastic film. The shed film is used to cover plastic sheds or small and medium-sized arch sheds and greenhouses; Plastic film is used to cover the ground or near the ground. Plastic film and plastic film have different classification methods.
1, classification of greenhouse films
Classification by materials: it can be divided into three types: PVC shed film, PE shed film and EVA shed film. Among them, PVC shed film has been eliminated and disappeared in the market because of serious environmental pollution. According to the performance characteristics, it can be divided into ordinary shed film, long-life shed film, drip-free shed film, long-life drip-free shed film, diffuse reflection shed film and composite multifunctional shed film. According to the molding process, it is divided into single-layer blown film shed film and multi-layer extruded blown film shed film. 2. Classification of plastic films
Plastic films are classified by color: colorless plastic films and colored plastic films. Classification according to functional purposes: there are mainly two kinds of ordinary plastic films and special plastic films. Among them, ordinary plastic films can be divided into broad-spectrum plastic films and thin plastic films; Special mulch film refers to mulch film with special functions, including weeding mulch film, microporous mulch film, reflective mulch film and degradable mulch film. Second, the performance characteristics of various agricultural films
1 and the performance characteristics of greenhouse film
(1)PE shed film
PE shed film is the main variety of shed film in China at present. It has the advantages of light and soft texture, good light transmittance and no toxicity. But the weather resistance and heat preservation are poor. The so-called weatherability refers to the tolerance of greenhouse film to comprehensive destructive factors such as light, cold, heat, wind and rain. The main products of PE shed film in the market are PE ordinary shed film, PE anti-aging shed film, PE drip-free anti-aging film and PE multifunctional composite film. The width and diameter of these shed films are generally 2~4 meters.
(2) Ordinary PE shed film
Ordinary PE shed film has a thickness of 0.06~0. 12 mm, light weight, strong light transmittance, less dust adhesion, slow decrease of light transmittance and relatively low temperature resistance, but it has poor moisture permeability, heavy fog drops, high temperature resistance, sunlight resistance, poor elasticity and rapid aging, and is not suitable for cultivation in high temperature seasons. Ordinary PE shed film is widely used in early spring or late autumn mulching cultivation in the middle and lower reaches of the Yangtze River in China. It is mostly used for the second curtain, membrane assembly or shed cover of greenhouse, and its service life is generally only 4~6 months.
(3)PE anti-aging greenhouse film
PE anti-aging greenhouse film, also called PE longevity greenhouse film by vegetable farmers, has a thickness of 0. 1 ~ 0. 12mm ... It not only has the advantages of PE ordinary greenhouse film, but also overcomes the disadvantages of high temperature resistance, sunlight resistance and rapid aging of PE ordinary greenhouse film. Can be used for more than two years, and can be used for planting crops in 2-3 seasons. Therefore, it is an ideal shed film for overwintering in the alpine region of northern China.
(4)PE drip-free anti-aging film
The PE drip-free anti-aging film is also called PE drip-free anti-aging film, PE double anti-aging film and PE long-life drip-free film, and its thickness is 0.08 ~ 0. 1.2 mm ... It not only has anti-aging characteristics, but also has anti-fog performance. The duration of droplets is generally 3~4 months. Compared with the common PE shed film, the weather resistance, light transmittance and heat preservation are improved, and the service life is 12~ 18 months. Suitable for solar greenhouses and large, medium and small greenhouses.
(5)PE multifunctional shed film
PE multifunctional greenhouse film integrates multiple functions, and its thickness is 0.08~0. 12 mm, which is mainly used in plastic greenhouses and solar greenhouses. Widely used in most areas of our country. The service life is generally 12~ 18 months. Anti-fogging and drip retention are valid for 3~4 months.
(6)EVA shed film
It is a high-end product in functional greenhouse film, which is superior to PE greenhouse film in light transmittance, heat preservation, weather resistance, fog prevention and flexibility, and it is not deformed before aging, easy to recycle after use and not easy to cause environmental pollution. The thickness of EVA shed film is 0. 1~0. 12 mm, and it can be used continuously for 1~2 years. The application of fruits, leafy vegetables and flowers in northern greenhouses can give full play to its effects.
2. Performance characteristics of plastic film
Common mulching films include broad-spectrum mulching films, namely colorless and transparent mulching films, thin mulching films with a thickness of only 0.008~0.0 1 mm, and various colored mulching films such as black mulching films and black-and-white mulching films.
(1) broad-spectrum plastic film
Broad-spectrum plastic film, also known as ordinary plastic film, is what we usually call five-color transparent plastic film. With a thickness of 0.0 12~0.0 16 mm and a width of 70~250 cm, it is the most widely used plastic film in production at present. It has the advantages of good light transmittance, rapid temperature rise and strong water retention, and is suitable for various areas, various mulching methods and various cultivated crops. The fly in the ointment is that it is easier to grow grass when covered with broad-spectrum plastic film, especially when the border surface is uneven or the plastic film is not closely combined with the border surface.
(2) Micro plastic film
The thin plastic film has a thickness of 0.008 ~ 0.0 1 mm and a width of 80 ~120cm. The performance of micro-mulching film is similar to that of broad-spectrum mulching film, but its light transmittance is not as good as that of broad-spectrum mulching film. In addition, it has a disadvantage that it is inconvenient to pick up the residual film after use. At present, in order to reduce white pollution, China has restricted the production and use of ultra-micro membranes with a thickness below 0.008 mm.
(3) Various colored plastic films
At present, colored plastic films on the market are mainly used in agricultural production, such as black plastic films, black-and-white double-sided plastic films, black-and-white bicolor plastic films, silver-black plastic films and blue plastic films.
Black plastic film: the thickness is between 0.0 14 and 0.025mm ... The light transmittance is very low. Although the temperature rising performance is not as good as that of broad-spectrum plastic film, the moisture retention performance is better than that of broad-spectrum plastic film. Suitable for high temperature cultivation in summer and autumn, or softening cultivation of leek, garlic and celery. In addition, black plastic film can significantly inhibit the growth of weeds, so it is effective in orchards and areas where weeds are seriously damaged.
Black and white double-sided plastic film: the front is milky white and the back is black. When covering, the front face is facing up and the back face is attached to the ground, which increases the reflection of light on the front face and prevents the transmission of light on the back face, so the cooling effect during the day is better than that of black plastic film. Good cooling and weeding effect, mainly used for heat-resistant cultivation of vegetables and fruits in summer and autumn.
Black-and-white double-color plastic film: it is a multifunctional plastic film with black-and-white stripes. When in use, the leucorrhea covers the crop rows, so that the crops can fully carry out photosynthesis and promote growth; Black belt is located between crops, which can effectively inhibit the growth of weeds between crops.
Silver-black plastic film: also known as aphid-avoiding film, it has the functions of moisturizing and rainproof, raising ground temperature, inhibiting weed growth and avoiding aphids. This is because the silver-black plastic film has strong reflective ability, and sunlight is reflected to the back of leaves through the silver-black plastic film, which plays a good role in repelling aphids who are afraid of seeing light. Suitable for disease-resistant and heat-resistant cultivation of eggplant, melons, vegetables, grapes and other fruit trees in summer and autumn.
Blue plastic film: Like blue filter, under the same illumination conditions, the transmittance of blue-violet light is higher than that of ordinary white plastic film, and blue-violet light is the most effective light for plant photosynthesis. Therefore, the use of blue modi seedling in agricultural production can greatly enhance the photosynthesis of crops and is conducive to the production of robust seedlings. Blue plastic film is mainly used to cover rice seedlings and plant vegetables, strawberries, peanuts and other crops.
Third, the choice of agricultural films.
Through the above introduction, I believe that you should not be too confused when purchasing agricultural films. When buying agricultural films, we should follow the following principles: First, choose regular manufacturers such as agricultural stores with reliable quality and good reputation to buy them. Secondly, according to the local climate conditions, crop types, coverage methods, and types of facilities, the appropriate agricultural film should be selected. Third, we should choose the type of agricultural film that suits us according to the actual demand and our own economic conditions, and don't blindly buy various functional films. Fourthly, it is necessary to calculate the reasonable usage amount according to the density, thickness, coverage area and coverage rate of agricultural film in advance, and buy it as needed to avoid unnecessary waste.
When buying, you should first check the label of the agricultural film to see if there is information such as the manufacturer's name, address, product certificate, specifications, standards, service life and production date. Secondly, check the appearance quality of agricultural film with eyes and hands. Good-quality greenhouse film should be elastic and uniform throughout the roll, with smooth appearance, no wrinkles, waterline or cloud markings on the surface, uniform thickness, consistent transparency, and consistent tensile force and elongation in horizontal and vertical directions.
How to judge the consistency of tension and elongation? There are usually two ways to judge. First, poke a hole in the agricultural film with your finger. According to the shape of the hole, if the hole is round and has burrs, it means that the vertical and horizontal tension has passed; If the hole is flat, or the agricultural film will tear in one direction when it is poked, it shows that the tensile force of the agricultural film is relatively poor. The second method is imitation and in-situ coverage. If you want to buy a fog drop shed film, you should pay special attention to distinguish whether it is a common film or a fog drop film. Generally, there is a small amount of powdery precipitation on the surface of non-dripping film. If there is no powdery precipitate on the surface of the film, then it is definitely not a non-dripping film. In addition, we can also put 50℃ hot water in the cup, and then attach the film to see the shape of water droplets on the inner surface of the film. If it appears in the form of dew, it means that the film is not drip-free, even if it is drip-free, it is an expired drip-free film.
Remind everyone that at the end of the purchase of agricultural film, don't forget to ask the merchants for invoices, receipts and other documents, and keep the vouchers and credit cards. So as to serve as a basis for safeguarding rights when there are quality problems in the future.
Fourth, scientific use of agricultural film.
Agricultural film belongs to perishable agricultural products. Only by mastering the scientific use method can the agricultural film play its due role to the maximum extent and prolong its service life, thus achieving the production purpose of saving costs and increasing efficiency. The so-called scientific use of agricultural film requires us to start with the details, so as to cover it correctly, use it reasonably and collect it properly.
1, correctly overwritten
(1) Correct coverage of shed film
Proper coverage of agricultural film plays a decisive role in prolonging the service life of agricultural film. First of all, covering the shed film should be carried out in sunny days with no wind or little wind, preferably in the morning or evening. Secondly, before we cover the shed film, there are several tasks that must be done well in advance. First of all, we should carefully check the skeleton of the shed, and all the parts that may scratch the shed film should be properly handled to avoid puncturing the shed film when covering the film. If the frame of the shed is made of ordinary iron wire instead of electroplated rust-proof metal wire, after one year of use, the iron wire is often seriously corroded and should be replaced with new iron wire. Even if the new iron wire is not replaced, it should be wrapped with cloth or old film. The joints in the greenhouse should be protected with plastic bags. The second is to clean up the stubble, bricks and stones of crops on the surface. Moreover, you need to master certain skills when covering the film to ensure that it is flat and wrinkle-free.
Many people cooperated when covering the film. First, roll up the two ends of the film with a bamboo pole, put the side marked with this face inward, and spread it on the left and right sides simultaneously in the greenhouse. After people on both sides of the greenhouse tighten the film, people at both ends pull it in the direction of both ends. After the membrane is tightened, a vertically symmetrical membrane pressing line is fixed on the covered membrane every one meter or so, and the lower end of the membrane pressing line is tied to the ground anchor, which requires tightening and fastening. Note that during the whole plastic film mulching process, you must not trample on the plastic film.
If the used old shed film is covered, it should be carefully checked for damage before covering. If there is any damage, repair the damaged position first, and then cover the film with the above method. Repair method can be used to repair the shed film, that is, cut a piece of film slightly larger than the damaged surface, cover the damaged part with the same texture, and connect it with thin lines and tight seams after padding. In addition, we can also use the hot patching method. After cleaning the damaged area, cover the damaged area with a slightly larger film, then cover it with 2~3 layers of newspapers, and then gently iron it along the seam with an electric iron. When the film is heated and melted, the upper and lower films are pressed tightly, and after cooling, the two films stick together.
(2) Correct plastic film mulching
Plastic film mulching is relatively simple, as long as the soil and debris on the ridge surface and the stubble of the previous crop are removed before plastic film mulching, and then covered along the border. When covering, it is required to tighten the plastic film as much as possible to make the film close to the ridge surface, and the two ends and the periphery of the film should be compacted with soil to prevent the film from being lifted by strong wind.
Remind everyone that different types of plastic film cover have different forces. For example, when covered with weeding plastic film, the side with herbicide should be attached to the ground. When covered with black and white double-sided plastic film, the white side faces up and the black side faces the ground. When covered with silver-black plastic film, the silver face is up and the black edge is attached to the ground.
2, the use of agricultural film precautions
The use of plastic film is very simple, so I won't say much here. Let's talk about the precautions in the use of greenhouse film.
For fruits and vegetables that need to be planted by scaffolding, it is best to use hanging ropes for cultivation. Scaffolding uses soft materials such as hemp rope and thread rope. If bamboo poles are used to set up the shed, care should be taken in scaffolding operation to avoid bamboo poles or bamboo joints piercing the shed membrane. The slope of the membrane surface should be greater than 25 degrees when the shed is buckled, otherwise it will affect the dripping effect. If there is dripping water on the shed film, it should be discharged from below in time to avoid excessive water accumulation and damage to the shed film. If the gap between skeletons is too large, some small skeletons should be added appropriately to prevent the off-line part of accumulated water from getting bigger and bigger and damaging the shed film. When uncovering the film for ventilation and covering the film for heat preservation, attention should be paid to gently uncovering the cover, gently pulling and putting it down to avoid puncturing or cutting the shed film. Greenhouse film is more prone to aging and damage after pollution, so it should be kept as clean as possible during use and the dust on the roof should be cleaned regularly. Special attention should be paid not to spray sulfur-containing pesticides, chlorine-containing pesticides, herbicides and other chemical pesticides on the greenhouse film. Once corroded by these chemical pesticides, the service life of greenhouse film will be greatly shortened. In the application process, attention should be paid to inspection, and once the shed film is found to be damaged, it should be repaired in time. Step 3 keep it safe
Plastic film is easy to be corroded and damaged during use, and it is difficult to recycle it. Therefore, what we call proper collection is mainly aimed at the shed film. After the end of a growing season, the greenhouse film with reuse value should be recycled in time and stored reasonably. Be careful in the process of recycling the greenhouse film to minimize the damage of the greenhouse film. The recycled greenhouse film should first remove the dirt and dust attached to it, and then rinse it with clean water. You can't rub it with your hands or hit it with a stick when washing. The cleaned greenhouse film should not be exposed to the sun. The correct treatment method is to pull the rope in a cool and ventilated place and gently spread the plastic film on the rope. When the greenhouse film is dried inside and outside, it is necessary to conduct a comprehensive inspection of the greenhouse film. If it is damaged, it should be repaired in time. In the case of confirming that the greenhouse film is not damaged, it should be folded neatly. In the process of folding, in order to prevent the greenhouse film from absorbing moisture in the future, a layer should be sprinkled on each layer of the greenhouse film. The folded greenhouse film should be stored in a dry, cool and ventilated place, away from direct sunlight and heat sources.
The vigorous development of agricultural plastic film mulching technology has opened a way for traditional agriculture in China to achieve high and stable yield, and made great contributions to China's agricultural and economic development. It is also hoped that farmers can choose and use agricultural film scientifically and reasonably and play a greater role in our agricultural production.