Advantages of Sunscreen Nets in Mulching Agriculture

Employing sunshade net mulching in farming serves to enhance the growth conditions for crops under cover, offering protection against adverse weather conditions, thereby ensuring consistent and superior crop cultivation. This method utilizes the multifunctional aspects of sunshade nets, providing summer shading, autumn and winter cooling, frost prevention, and mechanical protection against wind, rain, and insects. The primary benefits of employing sunshade net mulching in agriculture are outlined below:

Temperature Regulation and Cooling

During summer in regions like Southern China, where daily light intensity often exceeds 80,000-120,000 lux, coupled with scorching temperatures exceeding 30 to 35 degrees Celsius, crop photosynthesis can be inhibited due to excessive light exposure. This inhibition results from the destruction of plant chlorophyll, increased respiration, blocked transpiration, and disrupted physiological metabolism. Sunshade nets, with varying degrees of shading typically ranging from 25% to 75%, allow for the adjustment of light intensity to meet the photosynthetic needs of crops. Additionally, these nets provide a cooling effect, significantly reducing temperatures when applied during summer and autumn. Observations show that under the scorching sun of summer, temperatures can drop by 4-6 degrees Celsius in general, 5-8 degrees Celsius at ground level, and 8-14 degrees Celsius on the surface, creating optimal conditions for the growth of summer vegetables. Different colors and methods of sunshade net coverage yield varying degrees of cooling effects, with black nets offering superior cooling when applied externally to plastic greenhouses, and silver-gray nets proving more effective when used internally. Floating surface coverage with black sunshade nets is particularly effective in reducing ground temperatures.

Wind and Rain Protection

Sunshade nets effectively withstand summer typhoons and rainstorms, providing better protection for vegetables. The net's weaving disperses raindrops, converting heavy rainfall outside into lighter rain inside, thereby reducing the direct impact of raindrops on crops. This protective layer minimizes soil compaction and mitigates damage caused by rainfall. Measurements from Zhenjiang Meteorological Station in Jiangsu Province on August 4, 1986, during a rainfall of 34.6 mm within 100 minutes, showed a reduction of rainfall by 13.3% and 22.8% at the edges and middle of greenhouses covered with sunshade nets. Additionally, the impact force of raindrops under the net is significantly lower, only 1/50 of that on open ground. Sunshade nets, with their high mechanical strength and permeability, effectively reduce wind speeds, minimizing soil moisture evaporation and preventing direct crop damage. Measurements indicate that sunshade nets can reduce wind speeds by up to 60%, ensuring favorable growing conditions even in windy environments.

Thermal Insulation and Frost Protection

Utilizing sunshade net coverings during winter months in Southern China provides substantial benefits in terms of thermal insulation and safeguarding against freezing temperatures. Application of sunshade nets slows down water evaporation, elevates humidity levels, and retards surface heat loss. Within greenhouses, this method can elevate the lowest temperature by 1.4-5.1 degrees Celsius and increase the daily average lowest temperature by 2.3 degrees Celsius, with more pronounced effects in colder climates. When applied to open ground, sunshade nets typically raise the minimum temperature under the cover by 1-2.8 degrees Celsius and the daily average minimum temperature by 1.6 degrees Celsius. Data from the Zhenjiang Meteorological Station in Jiangsu Province indicates that surface humidity on open land covered by sunshade nets is either equal to or lower than uncovered land during daytime and 7 PM but higher from 10 PM to 7 AM.

In regions where winter temperatures aren't excessively low, sunshade net coverings effectively reduce ground radiation at night, providing a reliable defense against frost. During frosty nights, condensation of dew or fog on the net forms a protective layer of frost, shielding plants from direct harm. Furthermore, sunshade net coverings mitigate sudden temperature spikes at sunrise, reducing cell dehydration damage during freezing conditions.

In areas experiencing short-term snowfall during winter, sunshade nets act as barriers, preventing snow accumulation on crops and objects. This forms a protective layer that shields the microclimate environment beneath the snow layer from freezing damage. Such coverings facilitate easier vegetable harvesting and marketing post-snowfall—simply rolling up the net removes the snow, sparing the hassle of harvesting vegetables in snowy conditions.

Pest and Disease Reduction

Summer and autumn witness heightened pest activity, with aphids, diamondback moths, cabbage caterpillars, and noctuid moths being common nuisances. Utilizing the principle that aphids are deterred by silver-gray, manufacturers produce silver-gray sunshade nets, effectively repelling aphids. Closed cultivation using silver-gray sunshade nets significantly reduces aphid invasion and curbs the spread of viral diseases, thus minimizing pesticide usage and environmental pollution. With the advent of sunshade insect-proof nets, which combine sunshade mechanisms with pest prevention, the agricultural sector gains additional tools to combat vegetable pests.