Is thermal oxidation at different temperatures suitable to isolate soil organic carbon fractions with different turnover?     

Mirjam Helfrich  Heiner Flessa  Alexander Dreves  Bernard Ludwig 《植物养料与土壤学杂志》2010,173(1):61-66

Findings of previous studies suggest that there are relations between thermal stability of soil organic matter (SOM), organo‐mineral associations, and stability of SOM against microbial decay. We aimed to test whether thermal oxidation at various temperatures (200°C, 225°C, 275°C, 300°C, 400°C, or 500°C) is capable of isolating SOM fractions with increasing stability against microbial degradation. The investigation was carried out on soils (Phaeozem and Luvisol) under different land‐use regimes (field, grassland, forest). The stability of the obtained soil organic carbon (SOC) fractions was determined using the natural‐¹³C approach for continuously maize‐cropped soils and radiocarbon dating. In the Luvisol, thermal oxidation with increasing temperatures did not yield residual SOC fractions of increasing microbial stability. Even the SOC fraction resistant to thermal oxidation at 300°C contained considerable amounts of young, maize‐derived C. In the Phaeozem, the mean ¹⁴C age increased considerably (from 3473 y BP in the mineral‐associated SOC fraction to 9116 y BP in the residual SOC fraction after thermal oxidation at 300°C). An increasing proportion of fossil C (calculated based on ¹⁴C data) in residual SOC fractions after thermal oxidation with increasing temperatures indicated that this was mainly due to the relative accumulation of thermally stable fossil C. We conclude that thermal oxidation with increasing temperature was not generally suitable to isolate mineral‐associated SOC fractions of increasing microbial stability.  相似文献   

Modeling carbon dynamics in subsoils using simple models     

Mirjam Helfrich  Heiner Flessa  Bernard Ludwig 《植物养料与土壤学杂志》2010,173(5):671-677

Soil C dynamics below the plow layer have been little studied, despite a suspected large C‐stabilization potential of subsurface horizons. The objective of this study was to test two simple models (model A: single compartment for C₃‐ and for C₄‐derived C; model B: division of C₃‐ and C₄‐derived C into active and passive compartments) in their ability to simulate the C dynamics in subsoil horizons of a Haplic Phaeozem after conversion from C₃ (rye) to C₄ cropping (maize). The models were calibrated on an unfertilized maize soil and then validated on a maize soil with NPK fertilization. Both models simulated well C₃‐C and C₄‐C dynamics in the investigated soil depths (20–40 cm and 40–60 cm). In all cases, the model efficiency EF was > 0, which indicated that the simulated values described the trend in the measured data better than the mean of the observations. However, we observed some inconsistency in the obtained parameter set (e.g., a higher proportion of passive C for C₄‐derived than for C₃‐derived C or a very low decomposition rate constant for passive C₄‐C in 40–60 cm), which we assume to result from data restrictions on the investigated soils. More detailed data on SOC pools and turnover rates in subsoils which are generally not yet available for most experimental plots is vitally needed—especially for applying more sophisticated C‐dynamics models.  相似文献   

A cost-benefit analysis of Salmonella-control strategies in Danish pork production     

Goldbach SG  Alban L 《Preventive veterinary medicine》2006,77(1-2):1-14

In Denmark, it was agreed to lower the Salmonella prevalence in pork to 1.2% before the end of 2006. The current control did not seem to be sufficient to attain this goal. Therefore, four alternatives to the existing Danish control strategy for Salmonella in pork were compared in a cost-benefit analysis: (1) hot-water decontamination of all pigs at slaughter, (2) sanitary slaughter of pigs from herds with high levels of Salmonella, (3) use of home-mixed feed in herds with slaughter pigs and (4) use of acidified feed for slaughter pigs. The data originated from official statistics, published papers as well as expert opinion. The partial cost-benefit analysis was restricted to slaughterhouses affiliated with the Danish Meat Association and Danish human cases ascribable to pork from these slaughterhouses. Only hot-water decontamination was socio-economically profitable. Hot-water decontamination had a net present value over 15 years of 3.5 million euros. For sanitary slaughter the net present value was - 43.6 million euros, for home-mixed feed it was - 262.3 million euros and for acidified feed it was - 79.9 million euros. For all alternatives the costs were born solely by the pig sector, whereas primarily the consumers and public authorities received the benefits. The conclusions were robust in sensitivity analyses.  相似文献   

Acidity,nutrient stocks,and organic‐matter content in soils of a temperate deciduous forest with different abundance of European beech (Fagus sylvatica L.)     

Anja Guckland  Mascha Jacob  Heiner Flessa  Frank M. Thomas  Christoph Leuschner 《植物养料与土壤学杂志》2009,172(4):500-511

The production and composition of leaf litter, soil acidity, exchangeable nutrients, and the amount and distribution of soil organic matter were analyzed in a broad‐leaved mixed forest on loess over limestone in Central Germany. The study aimed at determining the current variability of surface‐soil acidification and nutrient status, and at identifying and evaluating the main factors that contributed to the variability of these soil properties along a gradient of decreasing predominance of European beech (Fagus sylvatica L.) and increasing tree‐species diversity. Analyses were carried out in (1) mature monospecific stands with a predominance of beech (DL 1), (2) mature stands dominated by three deciduous‐tree species (DL 2: beech, ash [Fraxinus excelsior L.], lime [Tilia cordata Mill. and/or T. platyphyllos Scop.]), and (3) mature stands dominated by five deciduous‐tree species (DL 3: beech, ash, lime, hornbeam [Carpinus betulus L.], maple [Acer pseudoplatanus L. and/or A. platanoides L.]). The production of leaf litter was similar in all stands (3.2 to 3.9 Mg dry matter ha^–1 y^–1) but the total quantity of Ca and Mg deposited on the soil surface by leaf litter increased with increasing tree‐species diversity and decreasing abundance of beech (47 to 88 kg Ca ha^–1 y^–1; 3.8 to 7.9 kg Mg ha^–1 y^–1). The soil pH_(H2O) and base saturation (BS) measured at three soil depths down to 30 cm (0–10 cm, 10–20 cm, 20–30 cm) were lower in stands dominated by beech (pH = 4.2 to 4.4, BS = 15% to 20%) than in mixed stands (pH = 5.1 to 6.5, BS = 80% to 100%). The quantities of exchangeable Al and Mn increased with decreasing pH and were highest beneath beech. Total stocks of exchangeable Ca (0–30 cm) were 12 to 15 times larger in mixed stands (6660 to 9650 kg ha^–1) than in beech stands (620 kg ha^–1). Similar results were found for stocks of exchangeable Mg that were 4 to 13 times larger in mixed stands (270 to 864 kg ha^–1) than in beech stands (66 kg ha^–1). Subsoil clay content and differences in litter composition were identified as important factors that contributed to the observed variability of soil acidification and stocks of exchangeable Ca and Mg. Organic‐C accumulation in the humus layer was highest in beech stands (0.81 kg m^–2) and lowest in stands with the highest level of tree‐species diversity and the lowest abundance of beech (0.27 kg m^–2). The results suggest that redistribution of nutrients via leaf litter has a high potential to increase BS in these loess‐derived surface soils that are underlain by limestone. Species‐related differences of the intensity of soil–tree cation cycling can thus influence the rate of soil acidification and the stocks and distribution of nutrients.  相似文献   

Effect of compaction on pore functions of soils in a Saalean moraine landscape in North Germany     

Stephan Gebhardt  Heiner Fleige  Rainer Horn 《植物养料与土壤学杂志》2009,172(5):688-695

Soil compaction and related changes of soil physical parameters are of growing importance in agricultural production. Different stresses (70, 230, 500, and 1000 kPa) were applied to undisturbed soil core samples of eight typical soils of a Saalean moraine landscape in N Germany by means of a confined compression device to determine the effect on (1) total porosity/pore‐size distribution, (2) saturated hydraulic conductivity, and (3) air conductivity to assess the susceptibility towards compaction. Different deformation behaviors after exceeding the mechanical strength particularly resulted from a combination of soil characteristics like texture and initial bulk density. The saturated hydraulic conductivity, as an indicator for pore continuity, was largely affected by the volume of coarse pores (r² = 0.82), whereas there was no relationship between bulk density and saturated hydraulic conductivity. Since coarsely textured soils primarily possess a higher coarse‐pore fraction compared to more finely textured soils, which remains at a high level even after compaction, only minor decreases of saturated hydraulic conductivity were evident. The declines in air conductivity exceeded those in hydraulic conductivity, as gas exchange in soils is, besides the connectivity of coarse pores, a function of water content, which increases after loading in dependence of susceptibility to compaction. A soil‐protection strategy should be focused on more finely textured soils, as stresses of 70 kPa may already lead to a harmful compaction regarding critical values of pore functions such as saturated hydraulic conductivity or air capacity.  相似文献   

Gateway重组系统快速构建花生条纹病毒cp基因反向重复序列载体     

晏立英  许泽永  陈坤荣  Rob Goldbach  Marcel Prins 《农业生物技术学报》2007,15(2):356-357

Gateway重组系统是Invitrogen公司推出一种新的克隆策略。鉴于一般用于农杆菌转化植物的质粒比较大，采用常规的酶切和连接的克隆策略耗时、费力，Gaytewayw重组系统为大载体的操作提供了一种快速和可靠的手段。该系统利用噬菌体转染细菌后整合细菌DNA的位点特异性重组策略（Landy，1989），重组过程是保守位点特异性DNA链的切割和重接，整个过程中没有DNA的合成。应用Gateway重组系统构建植物反向重复序列表达载体包括两个重组过程：第一，BP重组：目的片段重组至入门载体（Entry clone）；第二，LR重组，目的片段自入门载体重组至植物表达载体。本实验室拟利用这一系统构建花生条纹病毒（PStV）红安株系的cp反向重复序列载体，进行烟草转化，期望获得抗性的转基因植株。  相似文献   

NH3 and N2O Emissions after Landspreading of Slurry as Influenced by Application Technique and Dry Matter-Reduction. I. NH3 Emissions     

Robert Vandr  Joachim Clemens  Heiner Goldbach  Martin Kaupenjohann 《植物养料与土壤学杂志》1997,160(2):303-307

Ammonia volatilization from slurry is undesirable because of environmental N eutrophication and loss of fertilizer value. The dry matter content of slurry, the application technique and the weather conditions are the main factors influencing NH₃ losses from landspread slurry. In a field of winter wheat a two factor plot experiment was conducted to study single and combined effects of slurry separation and application techniques, including broadcast and banded application, as well as incorporation by injection and the flexible harrow. Ammonia volatilization from all treatments could be measured simultaneously, and at ambient climatic conditions by an indirect, open measurement technique. The experiment was repeated four times. Due to varying weather conditions and treatment effects, cumulative NH₃ volatilization from the slurry during the first 48 hours ranged from 4 to 90% of total ammoniacal nitrogen (TAN). Both separation and incorporation significantly decreased NH₃ losses, but only the combination of dry matter reduction and injection or harrowing reduced NH₃ volatilization to about 30% of TAN in all weather conditions. Banding alone did not efficiently conserve slurry N, but even enhanced NH₃ volatilization in wet conditions.  相似文献   

Boron in plants and animals: Is there a role beyond cell‐wall structure?     

Heiner E. Goldbach  Monika A. Wimmer 《植物养料与土壤学杂志》2007,170(1):39-48

The role of boron (B) as a structural element of plant cell walls and its implications for plant growth have been well established. However, increasing evidence suggests one or more functions of boron beyond cell‐wall structure. This evidence arises from studies conducted with a large variety of organisms, such as plants, animals, and bacteria. In animals, embryogenic development seems to depend on adequate boron supply, and cell lines with a knockout of the Na⁺‐coupled boron transporter NaBC1, the mammalian homolog of Arabidopsis thaliana boron transporter AtBor1, stop to develop and proliferate. In bacteria, boron is an essential part of a signal molecule required for quorum sensing. This review aims to summarize some recent advances from plant, animal, and microbiological research related to the functions of boron and to highlight open questions for further research.  相似文献   

Mist culture for mass harvesting of root border cells: aluminum effects     

Min Yu  Ying Ming Feng  Heiner E. Goldbach 《植物养料与土壤学杂志》2006,169(5):670-674

Root border cells, which form a cell layer around the root tip, seem to play multiple roles in the rhizosphere of the apical root. As these cells (species‐dependent dozens to several thousand per root tip) are rapidly sloughed off in water, studies in hydroponic culture fail to elucidate their role in most conventional physiological studies. The common method for harvesting these cells consists in germination of seeds in a humid atmosphere (usually a Petri dish), but labor and time constraints allow to yield only very limited amounts of uniform cells. We thus developed a low‐cost mist‐culture method, where intact border cells can be collected in the range of several grams. We applied this technique in a preliminary experiment where the influence of aluminum (Al) supply on calcium (Ca) release and viability of this cell type was studied. Purified detached border cells of pea were incubated with 0, 50, and 500 mmol m^–3 AlCl₃ solution (pH 4.5) for 90 min at a ratio of 3 × 10⁵ cells (4 mL)^–1. After incubation, cells contained 4.27 and 13.28 mg Al g^–1 C at 50 mmol m^–3 and 500 mmol m^–3 AlCl₃, respectively, while their total Ca content decreased correspondingly. Cell viability of border cells as tested by fluorescein diacetate‐propidium iodide (FDA‐PI) fluorescence yielded unexpected results: the test exhibited significantly lower vitality at 50, but not at 500 mmol m^–3 AlCl₃. Assessing mitochondrial activity by 3‐(4,5)‐dimethylthiazol‐2‐yl‐2,5 diphenyl‐tetrazolium‐bromide (MTT) reduction showed that viability decreased in a dose‐dependent manner with increasing Al concentrations. This apparent contradiction is attributed to the formation of dense mucilage around border cells at high Al concentrations, which likely inhibits the access of the dye PI or may chemically inactivate this compound and thus wrongly suggest higher viability. Mist culture allows harvesting selectively large amounts of homogeneous border cells quickly and to study their physiological reactions separated from the root tip.  相似文献   

Eschrich,W.: Funktionelle Pflanzenanatomie. Springer-Verlag: Berlin,Heidelberg, New York 1995, ISBN 3-540-59131-1, 388 S., 428 Abbildungen,Broschiert DM 78.—     

H. E. Goldbach 《植物养料与土壤学杂志》1996,159(3):314-314

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