The maximum effect of mulching cultivation is to increase the soil temperature. During the low temperature period in spring, the mulch film is covered by sunlight. After 0-10 cm deep, the temperature can be increased from 1-6 °C to above 8 °C. In the high temperature period, if there is no shading, the surface temperature of the soil under the plastic film can reach 50-60 ° C. When the soil is dry, the surface temperature will be higher. However, when there is crop shading, or when the surface of the mulch is covered with soil or silt, the soil temperature is only 1-5 °C higher than the exposed ground. When the soil is wet, the soil temperature will be 0.5-1.0 °C lower than the open field, and the highest temperature can be 3 °C lower. At night, the temperature of the soil under the membrane is only 1-2 °C higher than that of the exposed ground due to the influence of outside cold air. The warming effect of mulching film varies with the coverage period, coverage, weather conditions, and type of mulch film.
Due to the strong airtightness of the mulch film, the film can significantly reduce the evaporation of soil moisture after covering the film, so that the soil moisture is stable and can be kept moist for a long time, which is beneficial to root growth. In the arid areas, artificial phlegm and mites can be used for drought-resistant sowing. In the more arid conditions, the soil moisture content in the 0-25 cm deep soil layer is generally more than 50% higher than the open field. As the soil layer deepens, the water difference gradually decreases.
After the mulching film is covered, the crops are vigorous, and the transpiration consumes more water. Under the same management conditions, water shortage is easy to occur. Watering should be paid attention to to prevent drought and reduce production. Because the mulching film has the effect of warming and moisturizing, it is beneficial to the proliferation of soil microorganisms, accelerates the conversion of humus into inorganic salts, and is beneficial to crop absorption. It has been determined that the available nitrogen after mulching can increase by 30-50%, potassium by 10-20%, and phosphorus by 20-30%. After the mulch film is covered, the leaching, loss and volatilization of nutrients can be reduced, and the utilization rate of nutrients can be improved.
After the mulching film is covered, the middle and lower leaves of the plant can get 12-14% of the reflected light at the noon, which increases the light amount by 3-4 times than the open field, so that the apple in the lower part of the trunk can be colored well, the flowers of the flower are bright, and the color of the tobacco leaves is colored. it is good. The photosynthesis intensity of tomato can be increased by 13.5-46.8%, and the content of chlorophyll can be increased by about 5%. It can delay the aging period of middle and lower leaves and promote the accumulation of dry matter, so it can increase the yield.
When the mulch film and the surface are hot at sunny days, high temperatures of about 50 °C often occur, causing the grass buds and weeds to die. The use of herbicides in front of and behind the cover film prevents weeds from growing and reduces the labor required by the grass. However, poor quality of the film or no herbicide can cause grass shortage. After covering the mulch, the plant grows robustly, which can enhance disease resistance and reduce the incidence. Covering the Silver Black Mulch Film has a more evasive effect, which can reduce the spread of viral diseases.