Characteristics of maize residue decomposition and succession in the bacterial community during decomposition in Northeast China

Microbes are decomposers of crop residues, and climatic factors and residue composition are known to influence microbial growth and community composition, which in turn regulate residue decomposition. However, the succession of the bacterial community during residue decomposition in Northeast China is not well understood. To clarify the property of bacterial community succession and the corresponding factors regulating this succession, bags containing maize residue were buried in soil in Northeast China in October, and then at different intervals over the next 2 years, samples were analyzed for residue mass and bacterial community composition. After residue burial in the soil, the cumulative residue mass loss rates were 18, 69, and 77% after 5, 12, and 24 months, respectively. The release of residue nitrogen, phosphorus, and carbon followed a similar pattern as mass loss, but 79% of residue potassium was released after only 1 month. The abundance, richness, and community diversity of bacteria in the residue increased rapidly and peaked after 9 or 20 months. Residue decomposition was mainly influenced by temperature and chemical composition in the early stage, and was influenced by chemical composition in the later stage. Phyla Actinobacteria, Bacteroidetes, and Firmicutes dominated the bacterial community composition in residue in the early stage, and the abundances of phyla Chloroflexi, Acidobacteria, and Saccharibacteria gradually increased in the later stage of decomposition. In conclusion, maize residue decomposition in soil was greatly influenced by temperature and residue composition in Northeast China, and the bacterial community shifted from dominance of copiotrophic populations in the early stage to an increase in oligotrophic populations in the later stage.     

Spore production in the solid-state fermentation of stevia residue by Trichoderma guizhouense and its effects on corn growth

Trichoderma is an important and widely used plant growth-promoting fungus(PGPF). In this study, stevia residue amended with amino acids hydrolyzed from animal carcasses was used for the production of Trichoderma guizhouense NJAU 4742 by solid-state fermentation, and then its potential to promote corn plant growth was evaluated in combination with chemical fertilizer(CF) or organic fertilizer(OF). The highest spore number of 7×10~9 CFU g~(–1) fresh weight was obtained under the following optimal parameters: material ratio of 50%(stevia residue:rice bran=1:1), pH value of 3.0(amended with 6.67% amino acids), initial moisture content of 60%, inoculum size of 10%, material thickness of 3 cm and an incubation time of 4 days. The aboveground corn plant biomass obtained with T. guizhouense applied alone and with CF treatments were slightly higher than those of no fertilizer control and CF treatments, respectively. However, T. guizhouense applied with OF significantly(P0.05) increased aboveground biomass compared to OF and yielded the highest aboveground biomass among all the treatments. Moreover, T. guizhouense applications primarily influenced the fungal bulk soil community composition, among which three OTUs(OTU_2 and OTU_9 classified as Chaetomium, and OTU_4 classified as Trichoderma) were stimulated in both bulk and rhizosphere soil. Notably, a specific OTU_3(Phymatotrichopsis) was only stimulated by T. guizhouense applied with OF, possibly leading to high soil productivity. These results show that it is feasible to employ stevia residue in the eco-friendly fermentation of T. guizhouense, which is strongly suggested for enhancing OF applications.     

沼气肥养分物质和重金属含量差异及安全农用分析

对山西省高平市不同沼气肥有机质、养分和重金属含量进行比较分析,结果表明:沼气肥的p H值均呈碱性。鸡粪沼液中有机质、全N、P、K含量均高于猪粪沼液,秸秆沼液中有机质和全K含量高于鸡粪和猪粪沼液。沼渣富含有机质,且秸秆沼渣有机质含量均高于猪粪沼渣。猪粪沼渣全N含量高于全P和全K,而秸秆沼渣全K含量高于全N和全P;两类沼渣中有效P含量占全P的比重最大。3种沼液的中、微量元素均以Cl含量最高,且超过农田灌溉水质标准(GB5084-2005);Ca和Mg含量次之,Cu含量最低。6个沼渣的中、微量元素均以Ca、Fe含量较高;3个猪粪沼渣均以Cl含量较少,而3个秸秆沼渣均以Mn、Cu含量较低。1号猪粪沼渣As含量超过有机肥料标准(NY525-2012)。由此可见,部分沼液和沼渣可能存在有害物质过高的问题,从而影响其农用的价值和效果,存在潜在的生态环境风险。同时,应加强相关标准的制定和完善,以确保沼气肥的安全、高效农业利用。     

我国与CAC动物源性产品中药物残留限量的对比分析

国际食品法典委员会(Codex Alimentarius Commission,简称CAC)承担贸易仲裁的工作,CAC标准体系中制定了较多的产品质量标准,并将动物源性产品中药物残留规定统一到CAC/MRL2。重点对已有限量的动物源性产品中药物种类及残留限量值进行比较,将CAC中CAC/MRL2及我国农业部235号公告附录2中的内容进行比较,以期为今后不断健全和完善我国动物源性产品中药物残留法律法规、标准体系、检测手段,并为提高产品质量及扩大生产出口提供参考。     

利用农业废弃物资源改良中低产田效果

[目的]为了探索适用于中低产田改良的技术措施。[方法]采用不同农业废弃物资源,通过田间培肥的方式研究其对中低产水稻田土壤养分、作物产量的影响。[结果]与不施肥和单施化肥相比,化肥与秸秆、沼渣的配合施用对降低土壤容重,增加土壤有机质和速效磷含量的效果更加显著,化肥与秸秆处理还能明显增加土壤速效钾含量;在不同培肥方式中,化肥+沼渣处理作物产量最高;在秸秆还田措施中,与未添加腐熟剂的处理相比,添加腐熟剂能明显降低土壤容重,增加土壤有机质、有效磷、速效钾等养分含量。[结论]化肥与秸秆、沼渣的配合施用对中低产田土壤性质和肥力均有良好的改善作用。     

黔西南烟区中草药残渣替代基质烤烟育苗的研究

[目的]充分利用中草药残渣资源,验证其烤烟育苗的可行性.[方法]用中草药残渣基质和常规烤烟育苗基质开展烤烟育苗试验,研究中草药渣基质育苗对烤烟出苗率、生育期及成苗期农艺性状的影响.[结果]从出苗率来看,中草药渣基质育苗对烟草种子出苗率与常规基质育苗存在显著差异,出苗率低于常规基质;从烟草生育期来看,中草药渣基质育苗与常规基质育苗在出苗期、大小十字期、猫耳期有一定差异,但差异不大;从成苗期农艺性状来看,中草药渣基质育苗在茎围和叶片数上与常规基质差异显著,而茎高和侧根数指标无显著差异.[结论]中草药残渣具备漂浮育苗的基本条件,可进一步推广与应用.     

新疆农田地膜残留的影响因素分析

[目的]研究新疆农田地膜残留的影响因素,探讨农田地膜的残留规律.[方法]选择新疆31个地膜使用重点县市的棉田、玉米田和加工番茄田作为研究对象,分析覆膜年限、离村庄距离和作物种植种类对地膜残留规律的影响.[结果]农田覆膜年限、离村庄距离和作物种植种类对新疆农田地膜残留都有影响,其中农田覆膜年限和作物种植种类对地膜残留的影响较大.随着覆膜年数的增加,农田残膜密度会增加;离村庄距离＜1km的农田地膜密度相对较小;不同作物农田地膜残留规律不一致,同等条件下,加工番茄田残膜密度最小.[结论]该研究为新疆农田地膜污染的防治提供了理论依据.     

利用糠醛渣制备含腐植酸螯合态水溶肥料的技术

利用微生物发酵技术,使糠醛渣中的纤维素等大分子有机物质降解为更有利于被植物吸收小分子有机物质如腐植酸。利用碱提酸析的原理,从糠醛渣中提取腐植酸,制成腐植酸钾过饱和溶液,进行浓缩后加入大量、中量、微量元素化合物和螯合剂,再通过蒸发浓缩结晶成螯合态含腐植酸水溶肥料。该技术利用糠醛行业的废渣废水和化工材料制备水溶肥,变废为宝,资源综合利用,使得糠醛行业做到零污染零排放,为糠醛企业的发展指明方向。     

土霉素菌渣活性炭对亚甲基蓝吸附的研究

[目的]研究土霉素菌渣活性炭对亚甲基蓝的吸附.[方法]以土霉素菌渣活性炭为吸附剂,研究了pH、吸附温度及转速对土霉素菌渣活性炭吸附亚甲基蓝效果的影响,并采用准一级方程和准二级方程模型对反应动力学数据进行拟合.[结果]随着pH的增大,吸附量增大;吸附温度为35 cc时吸附量最大;转速为150 r/min时吸附量最大;准二级反应动力学模型能够较好地描述土霉素菌渣活性炭对亚甲基蓝的吸附动力学数据.[结论]该研究可为土霉素菌渣活性炭吸附亚甲基蓝废水的科学研究和合理利用提供科学依据.     

盐酸氯苯胍灌服后在兔尿液和粪便中的排泄规律

【目的】建立氯苯胍在兔尿液和粪便中的高效液相色谱检测方法,以测定氯苯胍在兔排泄物中的排泄量.【方法】12只健康新西兰大白兔灌服盐酸氯苯胍15 mg·kg-1后,于不同时间间隔收集其所有粪便和尿液,粪便称质量、尿液定容后冻存.称取0.2 g粪便,用体积比为2∶1的三氯甲烷-甲醇混合液提取,氮气吹干;量取1 m L兔尿,用体积分数为0.2%乙酸酸化的乙酸乙酯提取,氮气吹干,残渣均用乙腈-水(体积比30∶70)溶液复溶,CNW HLB柱净化,浓缩后用甲醇定容,上机检测.【结果和结论】氯苯胍在兔尿中的检测限与定量限分别为0.005和0.01μg·m L-1,通过尿液排泄的氯苯胍占给药总量的比例为0.56%;在兔粪便中的检测限与定量限分别为0.01和0.05μg·g-1,通过粪便排泄的氯苯胍占给药总量的比例为87.17%.氯苯胍在兔尿和粪便中排出高峰期分别在给药后0~6和6~12 h,占给药后累积排泄总量的比例分别为28.37%和38.46%.结果显示,该检测方法满足测定氯苯胍在兔尿和粪便中排泄量的要求,内服盐酸氯苯胍后大部分氯苯胍随尿液和粪便排出体外.