Molecular identification of detritivorous soil invertebrates from their faecal pellets     

Julia Seeber  Alexander Rief  Erwin Meyer 《Soil biology & biochemistry》2010,42(8):1263-1267

Faecal pellets of macro-decomposers form an important component of upper soil layers. It is, however, not yet specifically known which species’ faecal pellets are important in the process of humus and soil formation. Here we present a novel approach, based on the detection of short DNA fragments, to species-specifically assign faecal pellets to their detritivorous producers. Using diagnostic polymerase chain reaction (PCR), DNA of the two millipede species Cylindroiulus fulviceps and C. meinerti, abundant macro-decomposers on European alpine pastureland, could be detected in their faecal pellets. Although in both species detection was possible up to 5 days post-defecation (no longer intervals were tested), detection rates were significantly higher in C. fulviceps (81.3%) than in Cylindroiulus meinerti (60.9%) in repetitive PCRs. Employing a binomial mixture model, the probability that the producer’s DNA was present in a faecal sample which tested negative in five subsequent PCRs was estimated as 22.0% for C. fulviceps and 41.9% for C. meinerti, suggesting to adopt a flexible stopping rule for assaying this type of samples. This proof-of-concept study demonstrates that the molecular assignment of faecal pellets to their macro-invertebrate producers is possible, offering a new approach to examine the role of decomposer faecal pellets in soil formation and functioning as well as to complement molecular profiling of faunal communities.  相似文献   

Snowmelt runoff parameters and geochemical migration of elements in the dissected forest-steppe of West Siberia     

A.A. Tanasienko  O.P. YakutinaA.S. Chumbaev 《CATENA》2009

In three West Siberian geomorphological regions, the snowpack was measured and the soil frost depth, the volume of surface runoff, the humus content of the soil, and the chemical composition of meltwater were determined for each year from 1969 to 2007. The study was carried out on chernozem-type soils during different hydrological years. The water content of the snow varied in those years from 65 mm under low-snow conditions to 255 mm in very snowy winters. Both the amount of snow and the type of land use influence the surface runoff volume. Slopes covered with perennial grasses and plowland had the greatest snowmelt runoff values (> 50% of the water content of snow). The removal of clay particles depletes the humus from chernozem and phaeozem soils. Moderately eroded soil is transformed into medium-humus soil, and strong erosion leads to low-humus soil. In meltwater running on the surface of phaeozems situated near a cement factory, the concentrations of calcium and magnesium were 15- to 20-fold higher and carbon concentrations were 1.5-fold higher than in soils outside the pollution zone.  相似文献   

Transformation of 15N-labelled leguminous plant material in three contrasting soils     

F. Azam  R. L. Mulvaney  F. J. Stevenson 《Biology and Fertility of Soils》1989,8(1):54-60

Summary Two soils from Pakistan (Hafizabad silt loam and Khurrarianwala silt loam) and one from Illinois, USA (Drummer silty clay loam) were incubated with ¹⁵N-labelled soybean tops for up to 20 weeks at 30°C. Mineralization of soybean ¹⁵N was slightly more rapid in the Pakistani soils, and after 20 weeks of incubation, 50%, 53%, and 56% of the applied ¹⁵N was accounted for as (NH₄ ⁺+NO₃ ^–)-N in Drummer, Hafizabad, and Khurrarianwala soils, respectively. Potentially mineralizable N (determined by anaerobic incubation) varied between 1.5% and 10% of the applied ¹⁵N in the three soils at different stages of incubation; somewhat higher percentages were mineralizable in the Pakistani soils than in the Drummer soil. From 3.7% to 9% of the applied ¹⁵N was accounted for in the microbial biomass. From 10% to 32% of the applied N was recovered in the humic acid and fulvic acid fractions of the organic matter by sequential extraction with Na₄P₂O₇ and NaOH; from 12% to 49% was recovered in the humin fraction. Of the three soils, Drummer soil contained more ¹⁵N as humic and fulvic acids. In all cases, the ¹⁵N was approximately equally distributed between the humic and fulvic acid fractions. A significant percentage of the humin ¹⁵N (52%–78%, equivalent to 8%–34% of the applied ¹⁵N) occurred in non-hydrolyzable (6 N HCl) forms. Of the hydrolyzable ¹⁵N, 42%–51% was accounted for as amino acid-N followed in order by NH₃ (17%–30%), hydrolyzable unknown forms (20%–22%), and amino sugars (6%–2%). The recovery of applied ¹⁵N for the different incubation stages was 87±22%. Recovery was lowest with the Khurrarianwala soil, presumably because of NH₃ volatilization losses caused by the high pH of this soil.  相似文献   

Humus forms in terrestrial ecosystems: a framework to biodiversity     

Jean-François Ponge 《Soil biology & biochemistry》2003,35(7):935-945

Humus forms are the seat of most biological transformations taking place in terrestrial ecosystems, being at the interface between plants, animals and microbes. The diversity of terrestrial humus forms (mor, moder and mull) can be attributed to the existence of different patterns (strategies) for the capture and use of resources by ecosystems, in ascending order of biodiversity and bioavailability. Arguments are found in the parallel development of humus forms and terrestrial ecosystems, in exclusion mechanisms between organisms living in different humus forms, and in palaeontological studies. The diversification of terrestrial life forms in the course of Earth history, concomitant with an improvement in resource availability due to the development of sedimentary layers at the surface of continents, may explain the successive appearance of more active humus forms enabling the co-existence of an increasing number of organisms. Contradictory reports about the relationships between biodiversity and stability of ecosystems can be explained by the existence of different belowground pathways making ecosystems more stable.  相似文献   

Carbohydrates and aggregation in lowland soils of Nigeria as influenced by organic inputs     

R. Spaccini  J. S. C. Mbagwu  C. A. Igwe  P. Conte  A. Piccolo   《Soil & Tillage Research》2004,75(2):161-172

We evaluated the influence of several organic matter management practices on the characteristics of carbohydrates in water-stable aggregates and soil aggregate stability at three Nigerian locations (Abakiliki, Nsukka and Umudike) where forests had been converted to arable farming. The effect of management practices to enhance aggregate stability was site-specific. The highest aggregate stability was obtained with Gliricidia sepium at Abakiliki, with Cajanus cajan followed by rice mill wastes (RW) at Nsukka and with the forested soil at Umudike. While none of the treatments at all sites was able to enhance the C and N contents of the soils to the levels obtained in the forested sites, a net improvement in carbohydrate and organic carbon (OC) content was found for some management practices. The carbohydrate status increased with G. sepium at Abakiliki, and with Dactylodenae bacterii alone or in combination with Pentaclethra species at Umudike, while at Nsukka all organic inputs increased carbohydrate content over the control and forested soils. However, neither total OC nor the carbohydrate content were significantly correlated to the variability in aggregate stability of these soils. The δ¹³C values found for acidic hydrolysates were constant within the soil aggregate sizes and generally distributed around −29 to −30‰, suggesting that the OC from these sites originated from C3 plants. Our results indicate that in these tropical Nigerian soils, aggregate stability and OC content are generally preserved by alley-cropping in well structured soil, whereas treatments with organic wastes are sustainable management practices in more fragile soils.  相似文献   

羊粪与麦秸混合腐熟物含量对日光温室沙培甜瓜品质的影响   总被引：3，自引：0，他引：3       下载免费PDF全文

王忠红  李建明  邹志荣 《西北农业学报》2006,15(5):229-232

以厚皮甜瓜优选早蜜为材料,研究了沙化土与羊粪和麦秸混合的腐熟有机物以体积比所配不同基质的理化性能及不同基质对日光温室甜瓜品质和产量的影响。结果表明:随着基质中腐熟有机物含量的增加,甜瓜品质和产量呈先增高后降低的趋势。与习惯施肥栽培(对照)相比较,总体品质T3(羊粪和麦秸混合的腐熟物同沙化土的体积比为0.75∶1)最好,但产量最低;T2(羊粪和麦秸的混合腐熟物同沙化土的体积比为0.5∶1)产量最高,品质较好;对照虽在还原糖、总糖、vC上优于所有处理,但其硝酸盐含量最高。  相似文献   

Stability on the 109Cd, 65Zn Complex with Humus Acids     

HUA Luo  CHEN Shi-bao  BAI Ling-Yu  WEI Dong-pu 《中国农业科学(英文版)》2002,1(5):520-525

The radioactive isotope tracer and ion exchange balanced method was used to study the stability of 109Cd, 65 Zn complexes with humus acids. In the 109Cd and 65 Zn single existing system with humic acids,the stability constants of the humic-109 Cd (65 Zn) complex compound was higher than the fulvic-109 Cd (65 Zn)complex compound. The stability constant of the humic (fulvic) -65Zn was higher than that of the humic (fulvic)-109Cd. In the 109Cd and 65 Zn coexisting system, the stability constant and the co-ordination number of the humic (fulvic)-65Zn complex obviously increased, but the stability constant and the co-ordination number of the humic (fulvic)-109Cd complex obviously decreased as compared with its respectively single existing system.The result showed that the humus matter with higher molecular weight could more effectively reduce plant availability of heavy metals than that with lower molecular weight in polluted soil by heavy metals. The humus matter could more effectively reduce plant availability of Zn than that of Cd. Application of humus-acid increased the harm of Cd and decreased the harm of Zn to plants in Cd-Zn coexisting system.  相似文献   

环境材料对Pb、Cd污染土壤玉米生长及土壤改良效果的影响   总被引：5，自引：0，他引：5  

彭丽成  黄占斌  石宇  孙华杰  沈忱  陈威  张小明 《中国生态农业学报》2011,19(6):1386-1392

为探索环境材料对种植于Pb、Cd污染土壤中的玉米生长、品质的影响, 以及对Pb、Cd重金属污染土壤的改良效应, 本文采用温室盆栽方法, 研究了不同环境材料[腐殖质类材料(HA)、高分子材料(SAP)、煤基复合材料(FM)及粉质矿物材料(FS)]及其复合处理对Pb-Cd复合污染土壤中玉米(Zea mays L.)生长、品质及根系土壤环境的影响。结果表明, 添加环境材料组合F22(FM+SAP)、F23(FS+SAP)及F32(HA+SAP+FS)能促进苗期玉米生长, 长势好于对照; 所有环境材料处理中玉米地上部粗灰分含量都低于对照, 添加单一环境材料对玉米地上部粗淀粉含量的提高效果高于对照、优于组合; 处理FM、F33(SAP+FM+FS)及F4(HA+SAP+FM+FS)对土壤中Pb固定效果显著, 抑制土壤中Pb向玉米体内迁移; 单一处理FM、FS及组合F33(SAP+FM+FS)对土壤重金属Cd固化效果明显, 抑制土壤中Cd向玉米体内迁移。环境材料的添加在一定程度上有助于土壤基本理化性质的改善, 促进土壤改良, 同时环境材料对阻止土壤重金属向植物体迁移有一定作用。  相似文献   

围栏封育对退化草原土壤性质的影响   总被引：3，自引：0，他引：3  

李景刚  贾树海  赵国平 《安徽农业科学》2010,38(1):280-282

对内蒙古自治区锡林郭勒盟的羊草草原和大针茅草原长期围栏土壤的理化性质和腐殖质性质进行了研究。结果表明,围栏封育后,土壤容重下降,表面硬度减小,孔隙度和土壤毛管持水量增加;大针茅草原围栏封育样地土壤的有机质、全量养分和速效养分含量均有所增加;羊草草原围栏样地土壤的速效氮、速效磷含量增加,但有机质和全氮含量略有所降低。  相似文献   

典型黑土区不同生态系统下土壤团聚体中胡敏酸的结构特征   总被引：3，自引：0，他引：3  

郝翔翔  窦森  韩晓增  李明敏  安丰华 《土壤学报》2014,51(4):824-833

为了揭示生态系统类型对土壤团聚体中腐殖质分子结构的影响,本研究以黑土区24 a长期定位试验处理下的自然草地(GL)、耕地(CL)和裸地(BL)土壤为研究对象,采用湿筛法将土壤团聚体分为2 mm、2～0.25 mm、0.25～0.053 mm和0.053 mm 4个粒级,运用元素分析、红外光谱和差热分析技术,对团聚体中胡敏酸(HA)的结构性质进行了研究。结果表明,生态系统类型对团聚体中HA的分子结构产生了影响。耕地各级团聚体中HA的O+S含量以及(O+S)/C比值(摩尔比)普遍高于草地相应粒级团聚体,反映了耕地土壤团聚体中HA的氧化程度高于草地;差热分析中,耕地和裸地土壤团聚体中HA的中温放热量低于草地相应粒级团聚体,且二者的热量高/中比值均高于草地,说明耕地和裸地土壤团聚体中HA的芳香性/脂族性高于草地;草地和耕地土壤团聚体中HA在2 920和2 850 cm-1处代表脂族聚亚甲基和末端甲基中C-H伸缩振动的吸收峰明显强于裸地,脂族碳/羧基碳(2 920/1 720)以及脂族碳/芳香碳(2 920/1 620)比值高于后者。与自然草地相比,耕地和裸地生态系统会增强土壤团聚体中HA的缩合度、氧化度和芳香性,提高其分子结构的稳定性。  相似文献