Introduction and detailed information on plastic film covering

Principle

The biggest effect of mulching cultivation is to increase the soil temperature. During the low temperature period in spring, mulching with mulch can increase the temperature in the 0-10 cm deep soil layer after being exposed to sunlight during the day. 1-6℃, the highest temperature can reach above 8℃. Entering the high temperature period, if there is no shade, the temperature of the soil surface under the mulch film can reach 50-60°C. When the soil is dry, the surface temperature will be higher. However, when there are crops in the shade, or when the surface of the mulch film is covered with soil or silt, the soil temperature is only 1-5°C higher than that of the open field. When the soil is moist, the soil temperature will be 0.5-1.0°C lower than the open field, and can be as low as 3°C. At night, due to the influence of outside cold air, the soil temperature under the mulch film is only 1-2°C higher than that in the open field. The warming effect of mulch covering varies depending on the covering period, covering method, weather conditions and mulch type.

Due to the strong air tightness of the film, covering it with mulch film can significantly reduce the evaporation of soil water, stabilize the soil moisture, and keep it moist for a long time, which is conducive to root growth. In arid areas, methods of artificially creating and replenishing moisture can be used for drought-resistant sowing. Under relatively arid conditions, the soil moisture content in the 0-25 cm deep soil layer is generally more than 50% higher than in the open field. As the soil layer deepens, the moisture difference gradually decreases.

Crops covered with plastic film grow vigorously and consume more water through transpiration. They are prone to water shortages under the same management conditions. Pay attention to irrigation to prevent drought and yield reduction. Since mulching has the effect of warming and moisturizing, it is conducive to the proliferation of soil microorganisms, accelerates the conversion of humus into inorganic salts, and is beneficial to crop absorption. According to measurements, after covering with mulch, available nitrogen can increase by 30-50%, potassium can increase by 10-20%, and phosphorus can increase by 20-30%. Covering with plastic film can reduce leaching, loss, and volatilization of nutrients and improve nutrient utilization. However, the nutrients under mulching film are higher in the early stages of crop growth, but tend to decrease in the later stages. When producing vegetables, attention should be paid to top dressing in the later period, otherwise the yield will be affected. In addition, mulching can avoid soil compaction caused by irrigation or rainwater erosion, reduce the labor of cultivating, and make the soil loose and permeable. It can increase the total porosity of the soil by 1-10%, reduce the bulk density by 0.02-0.3 g·cm-3, and increase the stability of soil aggregates by 1.5%, so that the fertilizer, water, air and heat conditions in the soil can be coordinated. At the same time, it can prevent the occurrence of alkaline return and reduce the harm of salt staining.

After covering with mulch, the middle and lower leaves of the plant can get 12-14% more reflected light at noon, which is 3-4 times more light than in the open field. Therefore, the apples in the lower part of the trunk can be well colored, and the flowers can be The flowers are bright and the tobacco leaves are of good color. The photosynthesis intensity of tomatoes can be increased by 13.5-46.8%, and the chlorophyll content can be increased by about 5%. It can also delay the senescence period of the middle and lower leaves and promote the accumulation of dry matter, so the yield can be increased.

On sunny days, high temperatures of around 50°C often occur between the mulch film and the ground surface, causing grass buds and weeds to die. The use of herbicides before and after covering the film can prevent weeds from overgrowing and reduce the labor required for weeding. However, poor quality mulch or no herbicide application can also cause grass failure. After covering with mulch, the plants will grow robustly, which can enhance disease resistance and reduce the incidence of disease. Covering with silver-gray reflective film is more effective in repelling aphids and can reduce the spread of viral diseases.

However, there are some adverse effects in film-mulching cultivation. For example, if the film is covered for many years, the residual film will not be removed cleanly, causing soil pollution. Since the organic matter decomposes quickly after covering with film, crop utilization will be reduced. If the rate is high and fertilizer is not supplemented enough, the fertility of the land will decrease, or improper management of the mulching film will cause premature maturity, failure to increase production, or even decrease in production. In dry sandy land, barren land, and heavy clay soil, it is not suitable to use plastic film covering cultivation. Because the soil temperature after covering the dry sandy land with film is prone to high temperatures at noon, it will actually lead to a reduction in yields in severe drought conditions. On barren land, it is inconvenient to topdress after covering with film, insufficient base fertilizer is applied during sowing, and covering cannot increase production. Heavy clay soil becomes more lumpy during drought, making it difficult to rake and break the soil during soil preparation. It is difficult to stick to the ground after covering with film, and the film can easily be blown away when strong winds blow. Therefore, certain conditions must be mastered to achieve early maturity, high yield, and stable yield when using plastic film mulching for cultivation. Method

The method of mulching varies according to local natural conditions, crop types, production seasons and cultivation habits. Flat border covering

The border is flat and has border ridges. The width of the border is 1.00-1.65 meters, and the length of the border depends on the plot of land. Before sowing or planting, spread the mulch flat on the border and compact it with soil around it. Or temporary coverage in the short term. Covering saves labor and is easy to water, but it can easily cause silt pollution on the border surface after watering. The coverage has a warming effect in the early stage, and as the pollution increases, it has a cooling effect in the later stage. It is generally used for planting onions, garlic and vegetables on high seedling supports. It is also used for cutting crops such as wheat and cotton, and fruit forest seedlings. High ridge covering

The border is ridge-shaped, with a ridge bottom width of 50-85 cm, a ridge surface width of 30-50 cm, and a ridge height of 10-15 cm. Mulch is used to cover the ridge surface. The distance between ridges is 50-70 cm. Plant single or double rows of cabbage, lettuce, bell peppers, cauliflower, etc. in each ridge. The high ridge cover receives better light, the ground temperature is easy to rise, and it is also convenient for watering. However, the ridge height in dry areas should not exceed 10 cm.

Tall border covering

The border surface is flat-topped, 10-15 cm above the ground level, and the border width is 1.00-1.65 meters. The mulch film is spread flatly on the surface of the sorghum. Generally, vegetables grown on high seedling supports are grown, such as melons, beans, solanaceous fruits, grain and cotton crops. The high temperature in the high borderland has a better warming effect, but drought is prone to occur in the center of the borderland. Furrow covering

Make a furrow about 50 cm wide and 15-20 cm deep. Plant the grown seedlings in the furrow and then cover the furrow with mulch film. When the seedlings grow, they will bear on the mulch film. At this time, cut the mulch film into a cross at the top of the seedling, which is called cutting for air release. After the late frost, the seedlings will grow out of the film from the breach. When the seedlings grow taller, the film will be scratched, allowing it to fall to the ground and cover the roots. It is commonly known as covering the sky first and then the earth. This allows early planting 7-10 days. Protect seedlings from late frost damage. It not only protects seedlings but also protects roots, thereby achieving the effects of early maturity, increased yield and increased income. In early spring, vegetables such as cabbage, cauliflower, lettuce, beans, bell peppers, tomatoes, and cucumbers can be planted early, and melons such as watermelons and melons, as well as grain crops can also be sown early. For ditch planting, slope mulching

A slope-shaped ditch with a depth of 40 cm and a width of 60-80 cm is dug on the ground. The distance between the two ditches is 2-5 meters (2 meters for melons and 5 meters for watermelons). The ground between the two ditches is ridge-shaped. Cover the two sides of the ditch with 70-75 cm of mulching film along the slope, and the ground on both sides of the ditch is in the shape of a ridge. Cover both sides of the ditch with 70-75 cm of mulch along the slope, and plant melons on both sides of the ditch. Hole Covering

Use a hole drill to make holes on the flat border, high border or high ridge border. The hole is about 10 cm deep and 10-15 cm in diameter. Crops can be sown or planted in the hollow. The row spacing is determined according to the crop requirements, and then the top of the hole is covered with mulch film. After the top of the seedlings is filmed, the opening is cut to let out air. Potatoes and other crops can be grown. Form

1. The covering form suitable for cultivating cucumbers, green peppers, tomatoes, eggplants and other vegetables is to lay a mulch film with a width of 90--100 cm and a thickness of 0.01-0.008 mm on the high border surface. The side is buried and pressed 2/3-3/4 of the way down from the top of the border. The specifications of the sorghum border are: the width of the border bottom is 100-110 cm, the width of the border surface is 80-85 cm, the height of the border is 10-15 cm, and the width of the border furrow is 30--40 cm. When making a border, the center of the border should be slightly higher to facilitate the tight covering of the film.

2. The covering form suitable for cultivating onions, cabbage and other vegetables has a flat border width of 100-110 cm, and the border length can be customized according to the plot of land. Before planting, the mulch film can be spread flat on the border and compacted with soil around it. This method is more labor-intensive than sorghum, but it is easy to contaminate the border surface during irrigation and does not significantly increase the ground temperature.

3. The specifications of the large ridge covering form suitable for cultivating green peppers, cabbage and other vegetables are: 73 cm wide at the bottom of the ridge, 40 cm wide at the top, and 17 cm high. Cover the ridge surface with mulch and plant double or 3 rows in each ridge.

4. The covering form suitable for cultivating large-frame kidney beans is 53 cm wide at the bottom of the ridge, 33 cm wide at the top, and 16 cm high. Cover the ridge surface with mulch.

5. The covering form suitable for spring cabbage, radish, and root vegetables. After the cabbage and radish are sown in early spring, or before old-root spinach, leeks and other perennial vegetables turn green, the mulch film should be covered on the border for a short period of time. On the surface, it can promote its growth and go to market earlier.

6. The covering form suitable for cultivating green peppers, cucumbers, cabbage, tomatoes, kidney beans and other vegetables is to make a trench 40-50 cm wide and 15-20 cm deep on the high border surface, and plant the vegetable seedlings ( or direct sowing) in the trench and then covered with mulch. After slowing down the seedlings (after emergence), pierce or cut the mulch film on the top of the plant to let the wind out, and lead the seedlings out of the film after the late frost. This form allows early establishment before local late frosts.

7. The covering form suitable for cultivating potatoes is on the high border surface or large ridge surface. Use an eye drill to drill 15 cm deep planting holes according to the row spacing between plants, and sow or plant seeds or seedlings in the holes. , then cover with mulch, and let the air out after the seedlings emerge or slow down.

8. The covering form suitable for cultivating green peppers, cucumbers, eggplants and other vegetables is to break the large ridge into double ridges, sow or plant seeds or seedlings on the inner sides of the double ridges, and then cover them with mulch film. Allow the seeds or seedlings to grow for a period of time in the space between the two rows. After the late frost, the seedlings will be brought out of the film. Rice mulching film technology

This technology can not only greatly increase the rice yield in cold-soaked mud fields, high-rise Wangtian fields and water-deficient fields, but also plays an important role in solving the problem of relatively scarce water resources in our country. The mulched rice technology can increase the average yield by more than 100 kilograms per mu and save 100 to 400 cubic meters of water per mu. It has development prospects in both north and south of my country. This technology system mainly includes the wet cultivation technology of rice mulching and transplanting and the wet seeding technology of rice mulching in holes. The wet cultivation technology of film-covered rice transplanting is suitable for promotion and application in alpine fields, cold-soaked fields, dry hillock fields and water-deficient fields in the south. The wet seeding technology of rice film-covered hole sowing is suitable for use in the north where precipitation is less and water and heat resources are poor. Applicable to arid or semi-arid areas. Operating procedures

(1) Wet cultivation technology of rice mulching and transplanting

Selection of dry seedlings Select improved varieties with a slightly longer growth period than local conventional cultivation for dry seedling cultivation.

For field selection and field preparation, it is best to choose alpine fields, cold-soaked fields, dry hillock fields and fields lacking water. The fields should be flat and muddy. After the field is leveled and the water recedes, and before planting, apply more base fertilizer and more slow-release fertilizer.

When making the car cover, open "three ditches", that is, make a deep surrounding ditch, open a waist ditch, and open a shallow car ditch. After the "three ditches" are opened, the compartment surface is leveled and then covered with film by rolling the film bundle.

To transplant the rice seedlings according to the specifications, first nail the wooden nails on the wooden board to make a "hole punch" according to the spacing between the rows of the plants, punch holes in the film for sowing, and transplant the rice seedlings according to the holes. The rice transplanting time is about 10 days earlier than the local practice. After transplanting the seedlings, drain the water so that there is a thin layer of water on the membrane surface. Tobacco cultivation technology

Tobacco film-covered cultivation is divided into two types: cultivation under the film and cultivation on the film. Operating Procedures

Land preparation, ridging and fertilization. In areas with tobacco-rice rotation, tobacco leaves must be planted in mid-March, and the land must be prepared, ridged, and fertilized before February by taking advantage of favorable weather. Apply herbicide after ridging, then make holes to apply fertilizer, and break up the topsoil to cover with film.

Covering film. The soil surface must be moist, and the film can only be covered when the water holding capacity reaches 80%. Otherwise, the film cannot be covered. When covering the film, it should be close to the car surface, tightened and straightened, and the surrounding area should be pressed tightly with soil so that it cannot be blown by the wind.

Planting tobacco. For cultivation under film, if you cover the film before planting tobacco, uncover one side of the film when planting tobacco. After planting the seedlings, pour water and cover again with film. There was no film covering before planting the tobacco, and the film was covered immediately after planting the tobacco. If it is cultivated on film, make a small hole in the hole on the box surface, plant the tobacco seedlings into the hole, pour water and fertilizer, and press the film opening with soil.

Check the seedlings and replenish the stems. Within 7 days after planting, check the tobacco field and replace any dead seedlings promptly.

Open holes to lift seedlings. For tobacco seedlings cultivated under the film, when the leaves grow to withstand the mulch, holes must be opened in time, or when the temperature inside the film exceeds 30°C, holes must be opened in time to expose the leaves of the tobacco seedlings on the film surface, and the holes must be tied with soil. Press well. Otherwise, the smoke seedlings will be burned.

Remove the film. When the tobacco seedlings are covered with film for about 40 days, or when they reach the group stage, the film must be removed in time. The remaining film must be peeled off and dealt with centrally, and cannot be thrown around.