When will strawberry mulch be covered? Which color mulch should be used and how to lay it? What are the advantages of covering plastic film?

Plastic film mulching is the simplest protected cultivation mode, which does not require much facility investment. It can also be effectively combined with overwintering cold protection. When will the strawberry mulch be covered? Which color mulch should be used and how to lay it?

1. Types of plastic film

1. Black mulch film: the black polyethylene mulch film with high pressure and low density is most widely used in strawberry production, with a width of 0.5m to 0.8m and a thickness of 0.008~0.01mm. Ground mulching can significantly reduce the ground temperature, low light transmittance, effectively prevent the evaporation of water in the soil, inhibit the growth of weeds, and lengthen the fruit.

2. White plastic film: the black-and-white double-sided plastic film is milky white on one side and black on the other, with a thickness of 0.02 to 0.025 mm. Milky white upward, with reflective cooling effect; black downward, with herbicidal effect. The effect of cooling and weeding in high temperature in summer is better than that of black plastic film.

3. Silver gray plastic film: the light transmittance is about 60%, and it can reflect ultraviolet rays. The ground cover has the function of cooling, moisturizing and repelling aphids, which can increase the reflected light on the ground and is conducive to fruit coloring.

4. Red plastic film: red plastic film can stimulate crop growth more than black plastic film, and plants will use more energy for aboveground photosynthesis. Red plastic film can transmit red light, at the same time, it can block other color light which is not conducive to crop growth, so that crop growth is exuberant, which is conducive to strawberry fruit color change, improve coloring and sugar content.

5. Green plastic film: green plastic film can weed and increase temperature. Green plastic film mulching can reduce the visible light transmission of exuberant light and action of plants, while green light can increase, so it can inhibit the formation of weed chlorophyll, reduce the photosynthesis of weeds under plastic film mulching, and achieve the purpose of inhibiting weed growth. Its warming effect on soil is stronger than that of black film, and it can also promote aboveground growth and improve quality of strawberry and other crops. However, the price of green plastic film is more expensive, and it is easy to age, and the service life is shortened.

2. Mulching technology of plastic film

1. Plastic film mulching time: the plastic film covering time should be 7-10 days after plastic film holding, and it should be carried out before inflorescence, so as not to break the inflorescence during plastic film operation and affect flowering and fruiting. After strawberry planting in autumn, plastic film is generally covered before overwintering and before sprouting in early spring, but it is more advantageous to cover strawberry before overwintering in cold areas, and it is more suitable when the average temperature of the day drops to 3-5 ℃. It is easy to regenerate strawberries if covered prematurely.

2. Greenhouse is thoroughly disinfected.

Before buckling the plastic film, the strawberry greenhouse should be thoroughly disinfected to prevent and cure various diseases, and it is best to choose disinfection after continuous sunny days. This time, the disinfection of the entire greenhouse will be sprayed. The greenhouse with a spray volume of 400 square meters requires 7590 liters of liquid.

In addition to spraying, appropriate application of sulfur powder on the strawberry border, but not excessive, otherwise too much sulfur will lead to soil acidification, decrease in hardness, serious root rot and so on.

In order to facilitate strawberry management after film mulching, the following two things should be done well.

One is to flatten the strawberry border surface, to break the bumpy surface, gently eradicate the high part, try not to expose the strawberry root system, and the border surface should be flat and fine, so that the plastic film can be close to the ground to keep the plastic film flat.

The second is to tidy up the drip irrigation belt to ensure that the drip is uniform. If the border surface is very high, dig a shallow trench on the border surface and bring drip irrigation straight. If the strawberry plant is lower than the border surface, it is not serious to add some soil, if it is more serious to use sterilized straw pad below, the straw pad should be slightly higher, because the eyedropper belt will be pressed down when it is full of water, and the straw subsidence will affect the effect of drip irrigation. After finishing the border surface, the drip irrigation belt is straight and fixed in the center of the border surface by bending into a U shape with iron wire.

3. Laying plastic film

Select plastic film according to the width of the ridge to choose the width of plastic film, generally choose 90cm 120 cm wide plastic film.

When the plastic film is covered with plastic film, the plastic film is covered on the strawberry plant, so that the film surface is not wrinkled. in the solar greenhouse, two pieces of plastic film are often used in the cultivation, the stubble is in the middle of the strawberry bed, and the stubble coincidence length is kept at about 20 cm. The length of the plastic film is about 1 meter longer than the length of the border, and enough margin should be buried in the soil at both ends, which is not only beautiful but also ensures that the plastic film is relatively tight. Compared with the traditional way of laying plastic film in this way, it is convenient to operate and greatly reduces the amount of labor. it is not only not easy to break the stem, but also easy to carry out operations such as ploughing, weeding and topdressing.

When breaking the film, lift the seedling to cover the plastic film, along with the cover to break the film, take out the seedling to the film. Break the film to take out strawberry seedlings to keep the hole as small as possible, so as to avoid too large opening affecting the effect of plastic film warming and moisture conservation. Pay attention to take out the whole aboveground part of the strawberry, otherwise the strawberry leaves left behind are easy to mildew and breed pathogenic microorganisms, affecting the normal growth of strawberries. Film mulching should be carried out in windless weather and soften strawberry leaves in the afternoon to avoid breaking leaves and petioles easily in the morning because strawberry leaves are brittle.

Inflorescence has been extracted from the method of late film mulching: in production, it often occurs that the best time for laying plastic film is missed due to various reasons, resulting in inflorescence being thrown out. At this time, when laying plastic film, if we continue to take the way of breaking holes to lift seedlings, it is easy to fold flowers and affect the growth of strawberries. If the inflorescence has been extracted, when laying the plastic film, the plastic film in the root part of the strawberry plant can be divided into two parts with scissors from the edge, cut about 20cm length, then wrap the strawberry plant root system from both sides, and finally fix the interface tightly, so that the flower stem can not be broken.

Third, the advantages of covering plastic film

1. Impact on soil environment

1) increase the soil temperature.

Because the transparent plastic film is easy to pass through the short-wave radiation, but not easy to pass through the long-wave radiation, and the plastic film reduces the latent heat release of water evaporation, during the day, the sunlight passes through the plastic film and the ground temperature rises, and continues to transmit downward, but the underlying soil heats up. At night, the soil long-wave radiation is not easy to pass through the plastic film, but the heat release of the open soil is less, so the ground temperature is higher than that of the open field. The warming effect of plastic film mulching varies with different mulching time, mulching mode, weather conditions and types of plastic film.

2) improve the water retention capacity of soil.

After mulching plastic film, the soil water evaporation is small, so it can keep the soil moisture stable for a long time and prevent the soil from drying and wetting affecting the normal growth of crops.

3) improve the ability of soil fertilizer conservation.

Due to plastic film mulching, the soil under plastic film has suitable temperature and humidity, exuberant microbial activity and rapid decomposition of nutrients, so the contents of available nitrogen, phosphorus, potassium and other nutrient elements are higher than those in open field.

4) the physical and chemical properties of soil were improved.

Because plastic film mulching can avoid the impact of wind and rain on the soil surface, and reduce the soil consolidation caused by artificial and mechanical operations such as ploughing, weeding, fertilization, watering and so on, the soil bulk density, porosity, three-phase (gaseous, liquid, solid) ratio and aggregate structure are better than those without plastic film mulching.

5) prevent salt enrichment on the surface.

Plastic film mulching greatly reduces soil water evaporation due to cutting off the channel of water and atmospheric exchange, thus reducing the salt brought to the soil surface with water, which can prevent soil from returning salt.

2. The impact on the near-surface microclimate:

Due to the reflective effect of plastic film, it can increase light, which is beneficial to the photosynthesis of strawberry plants and increase product accumulation, and plastic film mulching can also reduce the air humidity in the greenhouse and effectively prevent the occurrence of diseases and insect pests.

3. Effect on the growth of strawberries:

Plastic film mulching creates good growth conditions for strawberries and promotes the development of strawberry roots. Strawberries grow healthily and enhance their own resistance, which speeds up the growth and development of strawberries, and each growth period is correspondingly earlier, so it can mature earlier and improve the yield and quality of strawberries.

4. Other effects: control weeds, save labor, save water and resist drought.