高温预处理联合生物炭堆肥产品对叶菜品质及有害物质累积的影响

【目的】集约化农业废弃物为主要原料的有机肥料中不同程度地存在有机、无机污染物,如何降低甚至避免污染物进入作物体内,对有机肥的安全利用意义重大。【方法】供试有机肥的主要原料为猪粪和麦秸,采用3种工艺制备了有机肥样品:常规堆肥(TC)、高温预处理堆肥(HTC)、高温预处理后添加生物炭堆肥(HTBC)。以生菜(Lactuca sativa)为材料进行了堆肥产品施用盆栽试验。在定植后50天取样,调查生菜叶片和根的鲜、干生物量。利用抖根法,采集根际土壤样品,分析叶片和根际土壤中重金属、抗生素含量及抗性基因(ARGs)的绝对丰度。同时,计算了生菜对重金属和抗生素的生物富集系数。【结果】与TC处理相比,HTC和HTBC处理分别增加生菜叶片鲜重9.2%和13.1%,提高可溶性蛋白质含量14.2%和8.3%,降低亚硝酸盐含量19.9%和19.4%;HTC和HTBC处理均能降低生菜叶片中重金属和抗生素含量以及ARGs绝对丰度,HTC处理降幅分别为6.0%~38.9%、22.4%~64.3%和41.6%~47.6%,HTBC处理降幅分别为13.8%~65.6%、33.0%~100.0%和59.2%~76.2%;HTC和HTBC处理的重金属富集系数分别降低8.7%~43.8%和8.0%~68.8%(Cd除外),HTC处理的磺胺类和四环素类抗生素富集系数分别降低14.5%~66.2%和4.5%~37.9%,而HTBC处理的降幅分别为33.4%~100.0%和34.2%~38.8%;在测定的11种抗生素中,HTBC可显著降低生菜根际土壤中9种抗生素的含量,而HTC只降低5种抗生素含量;在测定的6个ARGs亚型中,HTBC可显著降低5个ARGs的绝对丰度,而HTC只降低2个,HTBC对有害物质削减效果优于HTC。相关性分析结果表明,生菜叶片中重金属和抗生素含量以及ARGs的绝对丰度与根际土壤中对应污染物含量呈显著正相关。【结论】高温预处理联合生物炭添加堆肥工艺生产的有机肥可提高生菜产量与品质,同时降低根际土壤中的重金属和抗生素含量及ARGs丰度,进而减少了生菜的吸收和富集,有效削减生菜中有害物质的积累。因此,在高温预处理基础上添加生物炭进行堆腐,是减少作物对有机肥中重金属、抗生素和ARGs吸收积累的有效措施。

不同添加剂对鸡粪堆肥中氨气和温室气体排放的影响

堆肥是将畜禽粪污进行资源化的有效手段之一,但是氮素的流失会造成堆肥产品质量的降低,堆肥过程排放的氨气(NH_(3))和温室气体(N_(2)O、CH_(4)、CO_(2))会加剧空气污染和温室效应。减少堆肥过程中这些气体的排放,不仅可以提高堆肥产物的氮素含量,还可以减缓空气污染和温室效应。前期研究表明,加入添加剂(沸石、过磷酸钙和硫酸亚铁的混合物)或添加剂与菌株联用可以显著减少NH_(3)和N_(2)O的排放、实现堆肥产物保氮。为了进一步明确这3种添加剂对于堆肥中NH_(3)和温室气体的排放影响,选用鸡粪作为原料,将沸石、过磷酸钙、硫酸亚铁进行配伍组合,共设置8个试验处理进行室内模拟堆肥。结果表明,添加过磷酸钙和硫酸亚铁的处理(GL)对于NH_(3)的减排效果最好,为39.00%;添加沸石和过磷酸钙的处理(FG)对N_(2)O的减排效果最好,为7.19%;通过数据比较发现,堆肥氮损失中主要是由于NH_(3)的排放。CO_(2)是堆肥过程中气体排放占比最大的温室气体,各处理对于CO_(2)排放均有减排作用,其中添加硫酸亚铁的处理(L)、添加沸石和硫酸亚铁的处理(FL)对于CO_(2)减排效果显著,减排率分别为46.78%、34.26%。将上述3种温室气体转化为CO_(2)排放当量可以发现,3种添加剂均能减少CO_(2)排放当量,其中L处理的减排最好,减排率为45.57%,其次是FL处理、GL处理,分别为33.30%、32.48%。另外L、GL、FGL处理的堆肥产物中NH+4-N含量显著高于其他处理。沸石、过磷酸钙和硫酸亚铁不同组合中对NH_(3)和N_(2)O、CH_(4)、CO_(2)的排放影响存在显著差异,结合对NH_(3)和温室气体的减排效果和保氮能力,最后得出GL处理能作为一种较好的配伍组合,利用添加剂自身的吸附作用、pH等性质改变堆肥环境,减少堆肥中NH_(3)和N_(2)O、CH_(4)、CO_(2)的排放,这为畜禽粪便绿色高效资源化和减污降碳提供科学依据。

化肥减量增效技术及其农学、生态环境效应

化肥减量增效是国际社会的普遍共识,化肥是国家粮食生产的重要支撑,但农业生产的盲目性导致化肥滥用,对作物、生态环境产生负面影响,不利于农业健康持续发展。当前,我国化肥减量增效以“精、调、改、替”为技术路径,推广绿色生产方式。对化肥减量增效技术进行了归纳,并总结了减量增效后的农学、生态环境效应。化肥减量增效有利于改良培肥土壤,提升土壤生物多样性和土壤健康,在保障作物产量、改善农产品品质的同时,对农业面源污染控制、氨及温室气体减排也有积极作用。未来我国在充分借鉴发达国家环境友好型农业的基础上,应当坚持发展因地制宜、技术创新、政策惠民的现代农业,建立化肥减量增效的长效机制和规范体系。

微生物和化学添加剂对畜禽粪便堆肥过程活性氮气体的减排研究

堆肥是将畜禽粪污进行资源化的有效手段之一,但是氮素的流失会造成堆肥产品质量的降低,排放的氨气(NH_(3))和氧化亚氮(N_(2)O)会加剧空气污染和温室效应。为了减少堆肥过程中活性氮气体的排放、提高堆肥产物的氮素含量,选用猪粪和鸡粪作为原料进行室内模拟堆肥,设置接种微生物、加入化学添加剂或两者联用的试验处理。结果表明,加入化学添加剂的处理以及微生物和化学添加剂联用的处理能够显著减排活性氮气体,实现高效保氮的目的。在猪粪堆肥过程中,相对于未接种、未加入化学添加剂的对照,加入化学添加剂的处理、Bacillus sp.H3-1和化学添加剂联用的处理以及B.sp.H5-9和化学添加剂联用的处理NH_(3)减排11%~21%,N_(2)O减排4%~6%,堆肥产物中NH 4+-N含量增加6.7~7.7倍。在鸡粪堆肥过程中,相对于未接种、未加入化学添加剂的对照,加入化学添加剂的处理、B.sp.H1-10和化学添加剂联用的处理N_(2)O减排25%~26%,堆肥产物的NH_(4)^(+)-N含量增加3.3~3.9倍。因此,加入化学添加剂以及微生物和化学添加剂联用可协同减排NH_(3)和N_(2)O,实现堆肥产物保氮,该研究可为畜禽粪便绿色高效资源化和农业碳中和提供重要依据。

Bacterial Communities in a Buried Ancient Paddy Soil from the Neolithic Age

An ancient irrigated paddy soil from the Neolithic age was excavated at Chuodunshan Site in the Yangtze River Delta, close to Suzhou, China. The soil organic matter (SOM) content in the prehistoric rice soil is comparable to the average SOM content of present rice soils in this region, but it is about 5 times higher than that in the parent materials. As possible biomarkers to indicate the presence of the prehistoric paddy soil, the bacterial communities were investigated using the techniques of aerobic and anaerobic oligotrophic bacteria enumeration, Biolog analysis, and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that in the buried soil layers, the prehistoric paddy soil had the largest number of aerobic and anaerobic oligotrophic bacteria, up to 6.12 and 5.86 log cfu g-1 dry soil, respectively. The prehistoric paddy soil displayed better carbon utilization potential and higher functional diversity compared to the parent materials and a prehistoric loess layer. The Shannon index and richness based on DGGE profiles of bacterial 16S rRNA genes were higher in prehistoric paddy soil than those in the prehistoric loess soil. It might be concluded that the prehistoric irrigated rice cultivation accumulated the SOM in plowed soil layer, and thus increased soil bacterial populations, metabolic activity, functional diversity and genetic diversity. Bacterial communities might be considered as the sensitive indicators of the presence of the prehistoric paddy soil in China's Yangtze River Delta.

Multi-Fractal Analysis of Daily Air Temperature Time Series in Coastal Areas of China

In this article,the Multi-Fractal Detrended Fluctuation Analysis(MF-DFA)method is adopted to study the temperature,i.e.,the maximum temperature(Tmax),mean temperature(Tavg)and minimum(Tmin)air temperature,multifractal characteristics and their formation mechanism,in the typical temperature zones in the coastal regions in Guangdong,Jiangsu and Liaoning Provinces.Following are some terms and concepts used in the present study.Multifractality is defined as a term that characterizes the complexity and self-similarity of objects,and fractal characteristics depict the distribution of probability over the whole set caused by different local conditions or different levels in the process of evolution.Fractality strength denotes the fluctuation range of the data set,and long-range correlation(LRC)measures the stability of the climate system and the trend of climate change in the future.In this research,it is found that the internal stability and feedback mechanism of climate systems in different regions show regional differences.Furthermore,the research also proves that the Tavg,Tmaxand Tminof the above three provinces are highly multifractal.The temperature series multifractality of each province decreases in the order of temperature series multifractality of Liaoning>temperature series multifractality of Guangdong>temperature series multifractality of Jiangsu,and the corresponding long-range correlations follow the same order.It reveals that the most stable temperature series is that of Liaoning,followed by the temperature series of Guangdong,and the most unstable one is that of Jiangsu.Liaoning has the most stable climate system,and it will thus be less responsive to the future climate warming.The stability of the climate system in Jiangsu is the weakest,and its temperature fluctuation will continue to increase in the future,which will probably result in the meteorological disasters of high temperature and heat wave there.Guangdong possesses the strongest degree of multifractal strength,which indicates that its internal temperature series fluctuation is the largest among the three regions.The Tmaxmultifractal strength of Jiangsu is stronger than that of Liaoning,while the Tavgand Tminmultifractal strength of Jiangsu is weaker than that of Liaoning,showing that Jiangsu has a larger internal Tmaxfluctuation than Liaoning does,while it has a smaller fluctuation of Tavgand Tminthan Liaoning does.Guangdong and Liaoning both show the strongest Tminmultifractal strength,followed by Tavgmultifractal strength,and the weakest Tmax multifractal strength.However,Jiangsu has the strongest Tmax,followed by Tavg,and the weakest Tmin.The research findings show that these phenomena are closely related to solar radiation,monsoon strength,topography and some other factors.In addition,the multifractality of the temperature time series results from the negative power-law distribution and long-range correlation,in which the long-range correlation influence of temperature series itself plays the dominant role.With the backdrop of global climate change,this research can provide a theoretical basis for the prediction of the spatial-temporal air temperature variation in the eastern coastal areas of China and help us understand its characteristics and causes,and thus the present study will be significant for the environmental protection of coastal areas.