Don't let the film become a demon!

At present, the main raw material of mostplastic mulching film is polyethylene. Its molecular structure is very dense,and it is not easy to water and air permeability. It is precisely because ofthis feature that the plastic film made of it will not be decomposed even if itis buried underground for decades or even hundreds of years. That is to say,"it is not easy to degrade". Although every year farmers have toremove the damaged plastic film from the ground, there will always be somesmall pieces of plastic film left behind. If these plastic film fragments are turnedinto the soil layer, they will be like a transparent knife, both airtight andimpermeable, separating the soil layer into two separate layers. The roots ofplants growing in the upper layer cannot penetrate the plastic film to absorbthe water and nutrients in the lower soil, and the plants will be malnourished.At the same time, the water accumulated in the upper layer can not penetrateinto the lower soil in time.

The harm of residual agricultural film to theenvironment is mainly manifested in the following four aspects:

1. Harm to soilenvironment: due to the change of residual film fragments in soil or cuttingoff the continuity of soil pores, the movement of gravity water producesgreater resistance, so that the water permeability decreases due to theincrease of agricultural film residue, and the soil water content decreases,which weakens the drought resistance ability of cultivated land. Even lead tothe groundwater difficult to infiltrate, causing soil secondary salinizationand other serious consequences. In addition, residual agricultural filmaffected soil physical properties and inhibited crop growth and development.The main components of agricultural film materials are high molecularcompounds. Under natural conditions, these polymers are difficult to decompose.If they stay in the field for a long time, they will affect the permeability ofsoil, hinder the movement of soil water and fertilizer, affect the soilmicrobial activities and the formation of normal soil structure, eventuallyreduce the soil fertility level, affect the growth and development of croproots, and lead to crop yield reduction.

2. Harm to crops: as the residual film affects and destroys thephysical and chemical properties of soil, it is inevitable that the growth anddevelopment of crop roots are difficult. For the soil with residual film, itcan prevent the root system from collusion and affect the normal absorption ofwater and nutrients; when fertilizing between plants, there are large pieces ofresidual film isolated, which will separate the fertilizer, affect thefertilizer efficiency and reduce the yield. According to the determination ofthe Environmental Department of XPCC, the rotten seed rate was 6.92, the rottenbud rate was 5.17, the lateral roots of cotton seedling were reduced by 4.8-7.6pieces compared with normal, the death rate of 2-3 true leaf stage cottonseedling was 1.19, that of cotyledon stage was 3.08, and the budding stage wasdelayed 3-5 days. Plant height decreased by 6.7cm-12.9cm. The investigationdata showed that the difference of residual film on maize yield reached asignificant level. The yield of 9420 kg corn was 9420 kg per hectare in thefield with 187.5 kg plastic film residue, which was 909 kg less than that inthe control field without plastic film residue. The yield reduction rate was8.8.

3. It is the impact on ruralenvironmental landscape. Due to the limitations of recycling residual film,coupled with incomplete treatment and improper method, some of the residualfilm was discarded at the edge of the field and the ground. After the strongwind, the residual film was blown to the front and back of the house, the fieldand the tree top, which affected the rural environmental landscape, causing"visual pollution".

4. Harm to livestock. Theresidual film exposed on the ground is collected together with herbage. Aftercattle and sheep eat the residual film by mistake, it blocks the esophagus,affects digestion and even dies.

In a word, from the harm ofplastic film pollution to the environment and crop yield, it can be seen thatthe amount of residual plastic film in the field of plastic film cultivation isclose to or reaches the critical value of reducing crop yield. Therefore, theprevention and control of plastic film pollution is a very urgent andsignificant work.