【作者】 杨全刚；

【导师】 诸葛玉平；

【作者基本信息】 山东农业大学 ， 土壤学， 2017， 博士

【摘要】 我国地膜覆盖面积3.8亿亩,是世界其他所有国家覆盖面积总和的1.6倍。用量如此巨大,为农业生产带来巨大收益的同时,也带来了“白色污染”。而解决农膜“白色污染”的措施之一就是大力发展可降解液体地膜。本文通过小麦秸秆提取纤维素,在加入氧化锌的氢氧化钠/尿素/硫脲均相溶剂体系中制备了羧甲基纤维素,与可降解高分子物质聚乙烯醇、壳聚糖、明胶和腐植酸共混制备了生物质液体地膜（BLF）,改变5种物质的比例,获得了7种BLF（PCG1、PCG2、PCG3、PCG4、PCG5、PCG6和PCG7）,通过室内盐渍土失水试验、扫描电镜观察BLF与盐渍土表面结合形态、棕壤和盐渍土温室盆栽试验、田间试验,系统研究了BLF保水性、保水机理和对土壤理化性质、生物化学性质及对小麦苗期生长发育和产量的影响,从而获得组成BLF的5种物质的最佳比例。主要研究结果如下:1、在固液（过40目小麦秸秆粉和10%Na OH溶液）比为1:20（g/ml）,反应温度为85℃,回流3.5小时条件下处理小麦秸秆粉,再在固液（上述用10%Na OH处理的小麦秸秆粉和3%H₂O₂）比为1:30（g/ml）,反应温度为85℃,回流3小时条件下提取的小麦秸秆纤维素含量最高,达到84.61%,半纤维素和木质素脱除率分别为84.44%和91.14%。2、在氢氧化钠/尿素/硫脲溶剂体系中加入氧化锌能促进小麦秸秆纤维素的溶解,通过L₂₅（5⁶）正交试验证明,对该体系溶解小麦秸秆纤维素影响最大是氢氧化钠,其次为硫脲和氧化锌,影响最小的为尿素,该体系溶解小麦秸秆纤维素的最佳组成是:氢氧化钠7%,硫脲11%,尿素5%,氧化锌0.05%,在该体系最佳组成条件下,小麦秸秆纤维素的溶解度为2.8801 g。由小麦秸秆纤维素在该体系最佳组成条件下醚化合成羧甲基纤维素（CMC）的红外光谱与商品CMC的红外光谱特征峰基本相同,证明合成了CMC。决定CMC性质和用途的最重要的指标之一是取代度,影响合成CMC取代度的因素有小麦秸秆纤维素的用量、温度和氯乙酸钠与纤维素AGU（葡萄糖单元,anhydroglucose unit）的摩尔比,当小麦秸秆纤维素用量低于在该体系中的溶解度（2.8801 g）时,在氯乙酸钠与纤维素AGU的摩尔比（以下简称摩尔比）不变情况下,纤维素的用量增加,羧甲基纤维素的取代度明显提高。CMC的取代度随醚化温度的增高先升高（小于55℃时）而后降低。在同一小麦秸秆纤维素用量下,随摩尔比的增大,CMC的取代度逐步提高。3、腐植酸用量不超过0.1克能够保持PCG3的良好拉伸性能,对7种不同BLF进行拉伸试验,PCG3的断裂标称应变最大,达到105.51%,拉伸强度为4.7962 MPa。7种BLF均能抑制土壤水分的蒸发,其中以PCG3保水性能最好,第5天的累计失水率比对照（CK）显著降低6.6%（P<0.01）。4、BLF能通过覆盖土粒表面和阻塞土壤小空隙来抑制水分蒸发,扫描电镜观察喷施PCG3（原液40 ml稀释5倍,喷施面积100 cm²）的盐渍土,土壤表面相对平整,微小空隙减少,土粒表面为BLF覆盖。5、BLF（PCG3,1000 kg/hm²,稀释5倍）能够提高土壤水分含量和地温。田间试验中棕壤喷施PCG3第10天、20天含水量比CK高6.26%（P<0.01）和5.28%（P<0.01）。盐渍土喷施PCG3第40天含水量提高6.95%（P<0.01）。棕壤和盐渍土喷施PCG3后40天内土壤温度分别平均提高1.32℃（P<0.01）和1.99℃（P<0.01）。6、BLF处理能降低盐渍土阴离子和钠离子含量,提高钙镁离子含量。盐渍土盆栽试验中,7个BLF处理均能降低Cl^-、SO₄^2-、HCO₃^-和Na⁺含量,以PCG3降低最多,与CK相比分别降低0.13%（P<0.01）、0.091%（P<0.01）和0.0027%（P<0.05）、0.10%（P<0.01）;喷施PCG3处理的Ca²⁺、Mg²⁺含量比CK高0.010%（P<0.01）和0.014%（P<0.01）。盐渍土田间试验（PCG3,1000 kg/hm2,稀释5倍）中,PCG3处理的Cl^-降低0.070%（P<0.01）,SO₄^2-降低0.029%（P<0.01）,Na⁺降低0.0937%（P<0.01）,Ca²⁺、Mg²⁺含量增加0.0057%（P<0.05）和0.0076%（P<0.01）。7、BLF能够提高土壤有机质和养分含量,棕壤田间试验（PCG3,1000 kg/hm²,稀释5倍）中有机质和全氮分别提高0.53%（P<0.01）和0.031%（P<0.05）;速效磷钾分别提高4.06 mg/kg（P<0.05）和24.25 mg/kg（P<0.01）;盐渍土田间试验（PCG3,1000kg/hm²,稀释5倍）中有机质和全氮分别提高0.27%（P<0.01）,和0.033%（P<0.01）;速效磷钾增加3.18 mg/kg（P<0.01g）和18.12 mg/kg（P<0.01）。8、田间条件下,BLF有利于提高土壤微生物多样性。棕壤田间试验BLF处理PCG3的微生物多样性chao指数值为1977高于CK的1860;OTU总数提高5.8%,PCG3处理和CK中物种丰度百分数均值总和在前15的物种中有3个物种丰度差别达到特别显著（p<0.001）,2个物种丰度差别达到极显著（p<0.01）。BLF对盐渍土微生物多样性的影响效果显著,温室盐渍土盆栽PCG3、PCG4的微生物chao指数数值比CK提高接近500和400。盐渍土田间试验中PCG3微生物chao指数数值为2261,提高298。盐渍土盆栽试验中PCG3和CK的OTU总数分别为2037和1818,提高219。PCG3和CK的物种丰度百分数均值总和在前15的物种中,11个物种丰度差异达到特别显著（p<0.001）,1个物种丰度差别达到极显著（p<0.01）。盐渍土田间试验PCG3和CKOTU总数分别为2046和1628,提高25.68%,在物种丰度百分数均值总和在前20个物种中,19个物种丰度差异极其显著,其中OTU2924,OTU3148分别属于蓝细菌（Cyanobacteria）,其属于先锋微生物,生活在盐分高的极端环境中;OTU3003为黄杆菌目（Flavobacteriales）是盐碱地优势物种,而这三种微生物（OTU2924、OTU3003、OTU3148）在CK和PCG3分别占到7.334%和0.3515%、5.628%和0.8254%、5.871%和0.3775%。这样间接证明BLF处理中盐分浓度下降,能大幅度提高非盐碱地微生物物种的丰度。9、BLF能显著提高土壤蔗糖酶、磷酸酶活性。棕壤盆栽试验表明PCG3效果最好,蔗糖酶、磷酸酶、脱氢酶分别比CK提高6.10（P<0.01）个活性单位、0.47个活性单位（P<0.01）和0.012（P<0.01）个活性单位,脲酶提高0.008,差异不显著;棕壤田间试验中,PCG3处理的蔗糖酶、磷酸酶和脲酶活性提高5.57（P<0.01）、0.29（P<0.01）和0.16（P<0.01）脱氢酶活性提高0.016个活性单位,差异不显著。盐渍土盆栽试验中,PCG3效果最好,蔗糖酶和磷酸酶的活性分别比CK高3.38（P<0.01）和0.13（P<0.05）个活性单位,脲酶和脱氢酶活性提高0.029（P<0.01）和0.018（P<0.01）个活性单位。盐渍土田间试验中PCG3处理的蔗糖酶、磷酸酶和脱氢酶比CK高1.61（P<0.01）、0.10（P<0.01）和0.0090（P<0.05）个活性单位。脲酶活性提高0.012个活性单位,差异不显著。10、BLF对盐渍土盆栽小麦出苗率、地上部干重和钾钠比有显著影响,BLF处理平均出苗率、地上部干重和钾钠比值分别为81.68%、3.62和10.35,比CK分别增加17.58%、0.47g和6.35,其中以PCG3出苗率、地上部干重和钾钠值最高,分别高33.33%（P<0.01）、0.86（P<0.05）、8.7（P<0.01）。田间试验中PG3小麦产量比CK高0.62kg（P<0.01）。11、通过对BLF保水和提高地温作用大小、增加土壤有机质和养分含量的多少、提高酶活性和微生物多样性以及降低盐分离子含量和提高钙镁离子含量的总体分析,确定PCG3效果最好,PCG3的聚乙烯醇、羧甲基纤维素、壳聚糖、明胶、腐植酸各组分比例为1﹕3﹕0.6﹕0.4﹕0.1。更多还原

【Abstract】 Mulching area in China is about 380 million mu,which is 1.6 times the total area of the rest of the world.Great consumption brings“white pollution”of plastic while it brings Great benefits.The development of the biodegradable liquid film could control“white pollution”.In this paper,carboxymethyl cellulose was prepared from wheat straw,and biomass liquid film（BLF）was prepared by using carboxymethyl cellulose mixed with four kinds of biodegradable macromolecule polyvinyl alcohol,chitosan,gelatin and humic acid.Seven types of BLF（PCG1,PCG2,PCG3,PCG4,PCG5,PCG6,and PCG7）were obtained by changing the ratio of five substances.The morphology of BLF combined with saline soil surface was observed by SEM.Pot and field experiments of brown soil and saline soil together with water loss test were carried out to investigate the mechanism of water retention and the influence of BLF on physical,chemical and biochemical properties of soil.Also,the effect of membrane on wheat seedling growth and the yield of wheat were studied.And the optimum composition ratio of five materials to prepare BLF was confirmed.The main results are as follows:1.The wheat straw was treated at a solid-liquid（wheat straw powder,passing40mesh,10%Na OH solution）ratio of 1:20（g/ml）,under a reaction temperature of 85℃,refluxing for3.5 hours.Then,the reaction conditions were changed to a solid-liquid（the wheat straw powder treated with 10%Na OH,3%H₂O₂）ratio of 1:30（g/ml）,under the reaction temperature of 85℃,refluxing for 3 hours.The highest cellulose content extracted from the wheat straw is 84.61%.The removal rate of hemicellulose and lignin is 84.44%and 91.14%,respectively.2.Adding Zinc Oxide into Na OH/urea/thiourea solution could promote the dissolution of wheat straw cellulose.Through L₂₅（5⁶）orthogonal experiments,the dissolution of wheat straw fiber is most affected by sodium hydroxide,followed by thiourea and zinc oxide,but the minimal impact with urea in this system.The best composition ratio in the dissolve system is:caustic soda 7%,thiourea 11 wt%,urea 5%,zinc oxide 0.05%.Under this optimum composition,the solubility of wheat straw cellulose is 2.8801g.The infrared spectrum of carboxymethyl cellulose（CMC）synthesized by etherification of Wheat Straw Cellulose under the optimum composition is basically the same as that of the commercial CMC.The results confirmed that CMC is synthesized.One of the most important index to decide the property and application of the CMC is the degree of substitution.The factors affecting the degree of substitution are the dosage of wheat straw cellulose,temperature,the molar ratio of sodium chloroacetate to cellulose AGU（glucose unit,anhydroglucose unit）.When the amount of wheat straw cellulose is lower than the solubility（2.8801g）in the system,keeping the molar ratio of sodium chloroacetate with cellulose AGU（hereinafter referred to as the molar ratio）unchanged,the degree of substitution of carboxymethyl cellulose increased obviously by increasing the amount of cellulose.And the substitution degree of CMC increased with the increasing of etherification temperature（less than 55℃）,but then decreased.The substitution of CMC gradually increased with the increase of molar ratio,keeping wheat straw content unchanged.3.When the amount of humic acid is not more than 0.1 grams,the good tensile property of PCG3 can be maintained.The tensile test of seven kinds of BLF was carried out,and the nominal strain of PCG3 is the maximum,reaching 105.51%,whose tensile strength is 4.7962MPa.All of even kinds of BLF could inhibit the evaporation of water in soil,among which PCG3 has the best water retention,and the cumulative loss of water on the fifth day has a significant reduction of 6.6 percent（P<0.01）than that of CK.4.BLF can inhibit the evaporation of water by covering the soil particle surface and blocking small soil voids.Scanning electron microscope（SEM）was used to observe the saline soil with PCG3（40 ml,5 times dilution,spraying area 100 cm²）.The soil surface is relatively flat,the micro voids are reduced,and the soil particles are covered with BLF.5.BLF（PCG3,1000 kg/hm²,5 times dilution）can increase soil moisture content and soil temperature.In field experiments,the results of tenth days and twentieth days after spraying PCG3 in brown soil showed that water content is 6.26%（P<0.01）and 5.28%（P<0.01）higher than those of CK.Fortieth days after spraying PCG3 in saline soil,water content increased by 6.95%（1%LSD=1.54%）.Soil temperature on the fortieth days after spraying of PCG3 in brown soil and in saline soil increased by 1.32℃（P<0.01）and 1.99℃（P<0.01）,respectively.6.Spraying film treatment can reduce the content of anions and sodium ion in saline soil and increase the content of calcium and magnesium ions.In saline soil pot experiment,all of seven BLF treatments can reduce the Cl^-,SO₄^2-,HCO₃^-and Na⁺content.Among them,PCG3has the greatest decrease by 0.13%（P<0.01）,0.091%（P<0.01）and 0.0027%（P<0.05）,0.10%（P<0.01）compared with CK.By spraying PCG3 processing,Ca²⁺,Mg²⁺content is higher than CK by 0.010%（P<0.01）and 0.014%（P<0.01）.In the field experiments of saline soil（PCG3,1000 kg/hm²,5 times dilution）,PCG3 treatment decreased the content of Cl^-by 0.070%（P<0.01）,SO₄^2-by 0.029%（P<0.01）,Na⁺by 0.0937%（P<0.01）,but increased the content of Ca²⁺by 0.0057%（P<0.05）and Mg²⁺by 0.0076%（P<0.01）.7.BLF can improve the soil organic matter and nutrient content.In brown soil field experiment（PCG3,1000 kg/hm²,5 times dilution）,the content of organic matter and total nitrogen increased by 0.53%（P<0.01）and 0.031%（P<0.05）;rapidly available phosphorus and potassium contents increased by 4.06 mg/kg（P<0.05）and 24.25 mg/kg（P<0.01）,respectively.In saline soil field experiment（PCG3,1000 kg/hm²,5 times dilution）.The content of organic matter and total nitrogen increased by 0.27%（P<0.01）,and 0.033%（P<0.01）;rapidly available phosphorus and potassium content increased 3.18 mg/kg（P<0.01）and 18.12 mg/kg（P<0.01）,respectively.8.Under field conditions,spraying film could increase soil microbial diversity.The microbial diversity Chao index of brown soil field experiment of PCG3 treatment is 1977,higher than that of CK 1860.The total number of OTU increased by 5.8%.Three of the first fifteen sum of mean percentage value of species abundance were particularly different between PCG3 treatment and CK（p<0.001）and two species abundance difference reached significant（p<0.01）.The effect of BLF on microbial diversity of saline soil is significant,and the microbial Chao index of potted PCG3 and PCG4 in greenhouse saline soil increased by nearly 500 and 400 compared to those of CK.In potted experiment of saline soil,the Chao index of microbial treated by PCG3 is 2261,increased by 298.And the total OTU numbers of PCG3 and CK are 2037 and 1818,respectively,thus PCG3 treatment increased by 219.Eleven of the first fifteen sum of mean percentage value of species abundance were particularly different between PCG3 treatment and CK（p<0.001）,and one species abundance difference reached significant（p<0.01）.In saline soil field experiment,the total OTU numbers of PCG3 and CK are 2046 and 1628,respectively,thus PCG3 treatment increased by25.68%.Nineteen of the first twenty sum of mean percentage value of species abundance were particularly different between PCG3 treatment and CK,among which,OTU2924,OTU3148 belonging to the cyanobacteria（Cyanobacteria）,which belongs to the pioneer microbes that live in extreme conditions of high salinity;and OTU3003 as flavobacteriun mesh（Flavobacteriales）is the dominant species in saline alkali soil.The three kinds of microorganisms（OTU2924,OTU3003,OTU3148）in CK and PCG3 treatment accounted for7.334%and 0.3515%,5.628%and 0.8254%,5.871%and 0.3775%,respectively.This indirectly proves that salt concentration in jet membrane treatment can greatly increase the abundance of microbial species in non-saline alkali soil.9.BLF could significantly increase invertase activity and phosphatase activity in soil.Brown soil pot experiment showed that PCG3 treatment had the best effect,by which the invertase,phosphatase and dehydrogenase activities are higher than those of CK by 6.10（P<0.01）,0.47（P<0.01）and 0.012（P<0.01）activity unit,respectively.The difference of the urease with or without treatment is not significant.In field cultivation experiments of brown soil,invertase,phosphatase and urease activity with PCG3 treatment increased by 5.57（P<0.01）,0.29（P<0.01）and 0.16（P<0.01）activity units,respectively.Dehydrogenase activity increased by 0.016 activity unit,of which the difference is not significant with the CK.In saline soil pot experiment,the PCG3 treatment had the greatest effect on enzymes activity.The invertase and phosphatase activity are higher than those of CK by 3.38（P<0.01）and0.13（P<0.01）activity units,urease and dehydrogenase activity increased by 0.029（P<0.01）and 0.018（P<0.01）activity units.In field cultivation experiments of saline soil,sucrase,phosphatase and dehydrogenase are 1.61 higher（P<0.01）,0.10（P<0.01）and 0.0090（P<0.05）active units by PCG3 treated than those of CK.Urease activity increased by 0.012active units,and the difference is not significant between treatment and CK.10.BLF had significant effect on seedling emergence of wheat potting in saline soils,shoot dry weight and the ratio of potassium to sodium.The average seedling emergence rate,shoot dry weight and the ratio of potassium to sodium are 81.68%,3.62 and 10.35,respectively,which increased by 33.33%（P<0.01）,0.86（P<0.05）and 8.7（P<0.01）contrast to CK.When treated by PG3,the values could be the highest,which are 33.33%,0.86（P<0.05）and 8.7（P<0.01）,respectively.In the field cultivation experiments,the yield of wheat treated by PG3increased by 0.62 kg（P<0.01）contrast to the controls.11.PCG3 played the best role in increasing water retention rate,ground temperature,soil organic matter,enzymes activity,microbial diversity,calcium and magnesium ion content and reducing salt content,whose components are polyvinyl alcohol,carboxymethyl cellulose,chitosan,gelatin and humic acid with the ratio of 1:3:0.6:0.4:0.1.更多还原