Preparation And Application Of Fully Biodegradable Mulch Based On Cow Dung

The growth of beef and dairy product consumption has led to the rapid development of large-scale and intensive cattle breeding,and the resulting manure treatment problem is becoming increasingly serious.Extracting the rich cellulose in cow dung and preparing biodegradable mulch can not only solve the problem of cow dung treatment,but also solve the"white pollution"brought by traditional plastic mulch film.In this study,cow dung collected in Zhangye City,Hexi Corridor,China was taken as the research object.After the impurity removal treatment,the cow dung was mixed with wheat,corn,and flax straw to prepare cow dung liquid mulch film（CDLM）.The degradation of CDLM was observed,and the effects of CDLM on soil temperature and organic matters were analyzed.Through field experiments of silage corn,it was found that liquid mulch film prepared with cow dung improved the yield and water utilization efficiency of silage corn.Based on this,this study studied the composition of cow dung under conventional feeding conditions,established a cow dung fiber extraction method according to its composition characteristics,explored the physical characteristics and extraction process of cow dung fiber,optimized the production process of cow dung paper mulch film（CDPM）,studied the performance of the final mass-produced CDPM,and conducted field experiments to study the effects of CDPM on soil temperature,humidity,and the growth of silage corn.Finally,a systematic study on the cellulose extraction process of cow dung-physical properties of cow dung cellulose-preparation process of CDPM-research on the performance of mulch film-crop growth was formed,revealing the preparation mechanism of CDPM and its promotion effect on crop yield.The main achievements of this study are as follows:1.Liquid mulch film prepared from cow dung and straw can improve soil quality and increase crop yield.After the treatment of cow dung,the CDLM film prepared by mixing with straw has a certain thermal insulation effect and can be completely degraded within 100 days.After three years of continuous use,it can increase the organic matters of local soil（0～15cm soil layer）by 1.01%.Compared with polyethylene（PE）films,CDLM can better ensure the emergence rate.The results of field experiment showed that the yield of experimental fields using CDLM film was6.2%and 17.2%higher than that of the experimental fields using PE films and without any treatments,respectively.2.The length of natural fibers in cow dung is between 1～12 mm,but it is mainly concentrated between 3～4 mm,accounting for 51.5%.The cellulose content in cow dung is relatively high,reaching 41.6%,which is close to the cellulose content of conventional papermaking materials.After extraction,it can be used for papermaking,and provides the necessary conditions for the preparation of fiber based biodegradable mulch films.In this study,four extraction methods were used to treat cow dung,including hot water,hydrogen peroxide（H₂O₂）,sodium hydroxide（Na OH）and potassium hydroxide（KOH）boilings,and it was found that KOH boiling had the best extraction effect.Fourier transform infrared spectroscopy（FTIR）was used to compare and analyze the cleage of ether bond and ester bond between the lignin monomers or between lignin and polysaccharides in cow dung during the alkalization process.The results showed that the cementitious material in cow dung had been removed to form a separate single bundle of fibers;The X-ray diffraction（XRD）and thermogravimetry analysis（TGA）showed that the alkaline treated samples had higher thermal stability than the others,and had good removal effects on lignin and hemicellulose.At the same time,after KOH extraction,black liquor discharge is not achieved.By studying the influence mechanism of temperature and KOH concentration on the rate of fiber extraction and the physical properties of extraction,the optimal conditions for cellulose extraction of cow dung were as follows:KOH solution concentration was 10%wt,and the cooking temperature was 100°C.3.In this study,the wet forming papermaking method was used for the preparation and production of mulch films.The mechanical properties of the prepared pure cow dung paper film were as follows:the bursting strength was 2.48 KPam²/g,the tear index was 4.83 m Nm²/g,and the tensile strength was 26.72 Nm/g.In order to improve the mechanical strength of CDPM,this study optimized the preparation process of CDPM by adding KP pulp（coniferous wood fiber）,using the three-factor,three-level,quadratic orthogonal rotation center combination optimization test method,taking KP pulp mixing ratio,mulch film quantification and pulping degree as the influencing factors,and selecting tensile strength,burst resistance,and economic cost as the response functions.The results showed that the optimal combination of process parameters for the preparation of fully biodegradable mulch film based on cow dung was 60%KP pulp mixing ratio,120 g mulch quantification and 42.5°SR.In this study,scanning electron microscopy,optical microscopy,three-dimensional topography analyzer,infrared spectroscopy,XRD,TGA,and other equipment were used to compare and analyze the physical and chemical characteristics of CDPM at each stage,and study the degradation behavior of bovine manure based fully biodegradable mulch films.The results showed that the fully biodegradable mulch film based on cow dung produced by the optimized process has a bursting strength of 5.68 KPam²/g and a tensile strength of 56.86 Nm/g.It began to degrade after 60 days and completely degraded after 100 days,which meets the requirements of mechanical and degradation properties of mechanized laying in the field.5.Further field application performance tests showed that CDPM can improve the soil temperature and humidity environment for the growth of silage corn,ensure the seedling emergence rate,shorten the growth period,and promote the growth of silage corn.The number of roots of silage corn grown with CDPM is 47,with a maximum length of 49 cm.The plant height of corn can reach 314.87 cm,and the average stem diameter can reach 19.48 mm.The ear weight of silage corn is 16.13%higher than PE films,and 28.57%higher than no mulching（CK）;The whole plant weight is 11.24%higher than PE films and 27.73%higher than CK.In summary,this study conducted a systematic study on the utilization of cow dung fiber mulching film-the extraction process of cow dung cellulose-the physical properties of cow dung cellulose-the preparation process of CDLM-the study of mulching film performance-the crop growth;A fully biodegradable mulch film based on cow dung suitable for field application has been developed.Through the effective regulation of soil temperature and humidity,the PE films can promote the root growth of silage corn,so as to achieve the effect of increasing yield,replace polyethylene mulch film in the application of some crops,and reduce"white pollution".At the same time,it can also alleviate the issue of livestock cattle manure discharge and promote the development of agriculture and animal husbandry.