土壤农化分析实验课程是农业资源与环境专业的专业核心课程.针对课程前期教学中存在的问题,结合新农科背景下高质量人才培养需求,从学生实验操作能力与实验安全意识提升、实验兴趣培养与实验项目设置、教学方式及考核形式等环节对课程教学进行了改革探索.土壤农化分析实验课程的教学改革不仅有助于提高教学效率,还可以充分调动学生学习的积极性,提升新农科背景下应用型、复合型人才培养的质量.

To study the microbial community succession during cow manure composting under different ventilation conditions,using cow manure and straw as raw materials,two treatments of continuous ventilation (K1,aeration rates 0.2 L·kg -1 ·min -1 ) and intermittent ventilation (K2,average aeration rates 0.2 L·kg -1 ·min -1 ;aerate 10 min,stop 10 min) were set up to carry out aerobic composting experiment in the reactor.The microbial community succession and response to environmental factors were analyzed by high-throughput sequencing technology.The results showed that the bacterial and fungal community structure changed greatly in the entire composting.In the initial stage of composting,Proteobacteria （62.07%） in mixed raw materials of cow manure and corn straw was the dominant phylum of bacteria.Firmicutes was the dominant phyla in the thermophilic period,the relative abundance of Firmicutes in K2 treatment （83.09%） was significantly higher than K1 treatment （57.79%）.Bacillus and Solibacillus were the predominant groups in the thermophilic period of composting.The relative abundance of Bacillus in K1 and K2 treatments were 13.67%and 32.61%,respectively,and the relative abundance of Solibacillus were 7.2%and 23.05%,respectively.Ascomycota and Basidiomycota were the dominant phylum of fungi in the whole composting process.In the thermophilic period of composting,the proportion of Ascomycota in K1 and K2 treatments were58.11%and 78.11%,respectively.The relative abundance of Kurtzmaniella-Candida clade in K2 treatment （25.67%） was significantly higher than that in K1 treatment （7.85%）,which was the dominant genus in the thermophilic period of composting.The redundancy analysis （RDA） results showed that temperature,NH 4 + -N and C/N ratio were the main environmental factors affecting the bacterial and fungal community structure during the thermophilic period.The pH value,NO 3 - -N and TN had great influence on the bacterial and fungal community structure in cooling and maturity stage.Intermittent ventilation was beneficial to the increase of the relative abundance of Firmicutes in the thermophilic period of composting,and significantly increased the relative abundance of Bacillus and Solibacillus.Intermittent ventilation was beneficial to the increase of relative abundance of Ascomycota and Kurtzmaniella-Candida clade in the thermophilic period.

The objective of this research was to explore the effects of different aeration methods on NH3 and greenhouse gas (GHG) emissions and the losses of carbon and nitrogen from composting of cow manure and corn stalks in the laboratory-scale reactors. Here, we designed three treatments, including continuous aerated treatment C1 (aeration rates 0.21 L·kg−1 dry matter (DM)·min−1) and intermittent aerated treatments I1 (aeration rates 0.42 L·kg−1 DM·min−1; aerate 10 min, stop 10 min) and I2 (aeration rates 0.84 L·kg−1 DM·min−1; aerate 5 min, stop 15 min). The results showed that the physicochemical parameters (temperature, pH values, and germination index) of composting products met the requirements of maturity and sanitation. Compared with continuous aerated treatment C1, the cumulative NH3 emissions of I1 and I2 treatments decreased by 24.37% and 19.27%, while the cumulative CO2 emissions decreased by 13.01% and 20.72%. On the contrary, the cumulative N2O emissions of I1 and I2 treatments increased by 22.22% and 43.14%. CO2 emission was the principal pathway for the TOC losses, which comprised over 65% of TOC losses. C1 treatment had the highest TOC losses due to its highest cumulative CO2 emissions. The TN losses of I1 and I2 treatments reduced 9.07% and 6.1% compared to C1 treatment, so the intermittent aerated modes could reduce the TN loss. Due to the potential for mitigation of gaseous emissions, I1 treatment was recommended to be used in aerobic composting of cow manure.

Lignocellulosic materials have a complex physicochemical composition and structure that reduces their decomposition rate and hinders the formation of humic substances during composting. Therefore, a composting experiment was conducted to evaluate the effects of different C/N ratios on lignocellulose (cellulose, hemicellulose and lignin) degradation and the activities of corresponding enzymes during aerobic composting. The study had five C/N ratios, namely, T1 (C/N ratio of 15), T2 (C/N ratio of 20), T3 (C/N ratio of 25), T4 (C/N ratio of 30) and T5 (C/N ratio of 35). The results showed that treatments T3 and T4 had the highest rate of degradation of cellulose and hemicellulose, while treatment T3 had the highest rate of degradation of lignin. Among the five treatments, treatment T3 enhanced the degradation of the lignocellulose constituents, indicating a degradation rate of 6.86–35.17%, 15.63–44.08% and 31.69–165.60% for cellulose, hemicellulose and lignin, respectively. The degradation of cellulose and lignin occurred mainly at the thermophilic and late mesophilic phases of composting, while hemicellulose degradation occurred at the maturation phase. Treatment T3 was the best C/N ratio to stimulate the activities of manganese peroxidase, lignin peroxidase, polyphenol oxidase and peroxidase, which in turn promoted lignocellulose degradation.

为揭示通风方式对好氧堆肥过程中氮素转化及损失的影响,设置连续通风T1(通风速率0.2 L/(min·kg))和间歇通风T2(平均通风速率0.2 L/(min·kg),通风10 min,间歇10 min)2个处理,以牛粪和玉米秸秆为原料在反应器中进行好氧堆肥试验.结果 表明,堆肥结束后T1和T2处理总氮(TN)损失分别占初始TN 23.25％和21.12％,TN的损失以NH3挥发为主,分别占TN损失的74.76％和61.84％,而以N2O排放损失的氮仅占TN损失的1.12％和1.37％.NH3挥发主要集中在堆肥初期,主要是因为较高的温度和pH值所致,至堆肥结束时T2处理NH3累积排放量比T1处理少24.37％.不同通风方式对堆肥过程中NH4+-N和NO3--N的含量变化也产生显著影响,到堆肥结束时,T2处理相比T1处理,其NH4+-N含量低11％,而NO3--N含量高6.7％,T2处理酸解总有机氮含量比T1处理高12.4％,说明间歇通风有利于硝化作用和氨同化作用的进行.结构方程模型(SEM)显示,T2处理不同有机氮对NH4-N含量的总影响从大到小顺序为:酰胺态氮(1.006)、氨基糖态氮(0.485)、酸解未知态氮(0.034)、氨基酸态氮(-0.852),说明NH4+-N来源于酰胺态氮、氨基糖态氮和酸解未知态氮,同时NH4-N可以通过氨同化作用生成氨基酸态氮,间歇通风能促进NH4+-N向氨基酸态氮的转化.间歇通风方式通过抑制有机氮向NH;-N的转化,降低堆肥过程中由NH3排放造成的氮素损失.

利用牛粪和不同比例玉米秸秆的混合,设置5个不同C/N比处理(T1=15、T2=20、T3=25、T4=30、T5=35),研究其对条垛式好氧堆肥过程中的NH3挥发损失和含氮有机物转化的影响.结果表明:在肥堆前24 d有11.1％～23.1％ 的总氮损失,堆体C/N比越低,总氮损失率越高.堆肥结束时,T1～T5处理的总氮损失率为10.1％～24.1％,其中由NH3挥发造成的氮损失占总氮损失的30.9％～40.5％.堆肥过程的NH3挥发主要发生在升温期和高温期,此期的NH3挥发量占总挥发量的95％以上,是总氮损失的主要途径.堆肥前6 d各处理堆体铵态氮积累并达到最高值,导致pH值迅速升高,是造成堆肥NH3挥发的直接原因.堆体C/N比越低,pH值越高,NH3挥发量越大,由此造成的氮损失占总氮损失的比例越大.堆肥材料总氮的90％以上为有机氮,其降解主要发生在堆肥前24 d,堆体初始C/N比越低,有机氮矿化越快.不同有机氮组分的降解速率不同,以氨基酸态氮和酰胺态氮的降解为主.当堆体初始C/N比低于25时,堆肥材料中氨基酸态氮和酰胺态氮等有机态氮快速降解产生大量的铵态氮,由此导致堆体pH值的迅速升高,是导致堆肥过程中大量NH3挥发和氮素损失的主要原因.

为探讨不同畜禽粪便(牛粪和羊粪)为主料,添加不同作物秸秆(玉米秸秆和小麦秸秆)为辅料在堆肥过程中的碳转化特征及腐殖质组分的变化规律,采用条垛式好氧堆肥研究了不同原料组合(T1:牛粪+玉米秸秆;T2:牛粪+小麦秸秆;T3:羊粪+玉米秸秆;T4:羊粪+小麦秸秆)在堆肥过程中总有机碳(TOC)、可溶性有机碳(DOC)和腐殖酸含量的碳转化特征以及胡敏酸(HA)和富里酸(FA)的含量变化规律.结果表明:所有处理的TOC含量随堆肥过程的推进而下降,至堆肥结束时T1～T4处理的TOC含量分别下降了22.1％、21.5％、23.6、23.7％;DOC含量也随堆肥过程的推进而降低,至堆肥第15天时降低至最低,T1～T4处理分别降低至6.57、5.47、4.73 g·kg-1和4.93 g·kg-1,但不同处理的变化规律明显不同:以牛粪为主料的T1和T2处理在第10天以前几乎无变化,而以羊粪为主料的T3和T4处理从一开始就迅速下降至最低值,至堆肥第15天时T1～T4处理的降幅分别为32.4％、36.5％、51.8％和39.3％;总腐殖酸(THA)含量的增加始于堆肥的第10天,第15天时达到最高值,最高值分别为25.5％、22.5％、29.8％和30.0％,整个堆肥过程中T3和T4处理显著高于T1和T2处理(P<0.05).随堆肥过程的推进,游离腐殖酸(FHA)含量逐渐降低,堆肥结束时降幅为7.6％～18.0％;HA含量逐渐增加,至堆肥结束时增幅为65.4％～197.8％,堆肥过程提高了胡敏酸态碳.T3和T4处理的FHA和HA含量在整个堆肥过程中始终高于牛粪组合T1和T2处理.FA含量随堆肥进程推进逐渐下降,至堆肥结束时降幅为44.9％～54.9％.羊粪中较高含量的纤维素、半纤维素和HA可能是堆肥产品中THA和HA含量较高的主要原因,在以牛粪为主料的堆肥配料中适当加入羊粪可以提高堆肥产品的腐殖酸含量和胡敏酸态碳.

[目的]探讨不同C/N牛粪玉米秸秆在好氧堆肥中的碳素转化规律.[方法]本试验于2017年7月6日至8月19日在白银市鑫昊生物科技有限公司进行了为期45 d的好氧堆肥试验.试验采用条垛式堆肥,设置五个C/N处理:T1 (C/N=15)、T2 (C/N=20)、T3 (C/N=25)、T4(C/N=30)和T5 (C/N=35),研究不同C/N对好氧堆肥过程中总有机碳(重铬酸钾容量法)、腐殖酸及其组分含量(焦磷酸钠-氢氧化钠提取重铬酸钾氧化容量法)以及各腐殖化参数变化规律的影响.[结果]总有机碳的降解主要发生在堆肥的前15 d,C/N越高,有机碳降解率越高,T1～T5总有机碳的降解率分别为25.9、35.2％、43.2、43.6％和47.9％.总腐殖酸和游离腐殖酸的含量均呈下降趋势,在整个堆肥过程中T1～T5处理总腐殖酸含量降幅分别为23.8％、15.1％、14.2％、29.2％和45.3％,游离腐殖酸含量降幅分别为39.9、10.5％、16.8％、51.3％和29.1％,2种腐殖酸含量降幅均是以C/N=20和C/N=25的T2和Ta处理最小.(3)不同C/N堆肥产品中胡敏酸和富里酸含量均无显著性差异(P＜0.05),相较于第0天,C/N最高的T4和T5处理胡敏酸含量增幅比其余处理低了23.5％～33.1％;在整个堆肥过程中,以C/N=25的T3处理富里酸含量降幅最大.C/N=25的T3处理其产品H/F不仅显著高于其他处理(P＜0.05),在整个堆肥过程中增幅也最大;不同C/N堆肥产品PQ值无显著性差异(P＜0.05),相较于第0天,各处理PQ值的增幅分别为68.1％、55.4％、68.6％、41.0％和42.3％,以C/N=25的T3处理PQ值增幅最大;T1～T5处理堆肥产品HR值分别为59.0％、62.0％、61.0％、41.3％和49.0％,C/N最高的T4和T5处理堆肥产品HR值显著低于其他处理.[结论]高C/N(＞30)会造成总有机碳的过量损失、不利于肥堆中胡敏酸的生成和积蓄,并对其堆肥产品的腐殖化程度产生显著负面影响;当堆体C/N在20～25时,更有利于好氧堆肥中腐殖酸类物质的生成和积蓄;当堆体C/N=25时,最有利于堆体中富里酸的稳定化,其产品腐殖化程度也最高.

[目的]探究有效处理畜禽粪便与秸秆废弃物的方法,建立以牛粪有机肥为原料的高效堆肥工艺.[方法]以牛粪和玉米秸秆为原料,设置C/N为15、20、25、30、35的5个处理组,研究不同碳氮比原料对好氧堆肥过程中堆温、pH、矿质态氮含量、总养分含量、种子发芽指数等指标的影响.[结果]C/N为30的处理组升温最快,且60℃以上高温维持时间最长;各处理组的铵态氮含量均随堆肥逐渐下降,硝态氮含量逐渐上升;至堆肥结束时,C/N为30的处理组铵态氮含量下降了24.26％,铵态氮损失最少;C/N15～C/N35各处理组总有机碳含量随堆肥的腐熟不断下降,至堆肥结束分别降解了25.93％、35.22％、43.22％、43.58％、47.88％.堆肥结束时,各处理的C/N值分别为13.4、13.4、13.2、15.0和15.3,总养分含量均有所增加,且C/N为25时增幅最大,为45.79％;种子发芽指数(GI)随C/N的增加而增高,堆肥结束时C/N为15和20的处理组基本腐熟,其余处理已完全腐熟.[结论]在实际生产中,牛粪与秸秆C/N在25～30之间有利于堆体腐熟和养分保持.

该试验采用水培试验设计,针对我省河西灌区的马铃薯立枯丝核菌毒素对幼苗不同器官组织细胞膜伤害的影响进行了研究.试验结果表明,用立枯丝核菌毒素处理了马铃薯幼苗的茎、叶组织质外体汁液的电导率显著高于其它未处理的.其说明进行立枯丝核菌毒素处理以后,致使马铃薯幼苗的不同器官组织的细胞膜遭到损伤后其细胞里的电解质开始外渗;而且研究还发现幼苗不同器官组织细胞膜上的H+-ATPase的活性相比对照处理也显著升高,且在立枯丝核菌毒素处理后48h,幼苗不同器官组织细胞膜上的H+-ATPase的活性均达到峰值,之后随时间的变化又出现下降趋势,相比茎,其叶片的反应相对滞后.

[目的] 比较以羊粪、牛粪、猪粪和鸡粪为主料,玉米秸秆为辅料,在堆肥过程中微生物区系和养分含量的变化.[方法] 用平板培养计数法和国家有机肥行业标准规定的方法测定春季堆肥中可培养微生物数量和养分含量的变化,并比较冬季和春季不同季节堆肥过程的温度变化.[结果] 春季堆肥较冬季堆肥升温速度快,高温(60~65 ℃)期持续时间长(9~12 d),堆肥周期短,有利于提高生产效率;堆肥至第30天时,即可达到腐熟标准,冬季堆肥需要40 d方可达到腐熟标准;不同畜禽粪便堆肥过程中以鸡粪为原料的堆肥中可培养微生物数量最多,在高温阶段下降的幅度最小,为91.1%;鸡粪堆肥的有机质含量亦最高,为48.6%;总养分(N+P2O5+K2O)含量升高的幅度最大;达到42.4%;羊粪堆肥的放线菌数量在堆肥过程中的增加幅度最大,为74.8%,有利于堆肥后期木质素的分解.[结论] 因此,当地企业在以牛粪和玉米秸秆为主要原料进行堆肥时,可加入适量鸡粪和羊粪,以提高堆肥的生产效率和产品品质.