Tillage system affects fertilizer-induced nitrous oxide emissions

Since the development of effective N₂O mitigation options is a key challenge for future agricultural practice, we studied the interactive effect of tillage systems on fertilizer-derived N₂O emissions and the abundance of microbial communities involved in N₂O production and reduction. Soil samples from 0–10 cm and 10–20 cm depth of reduced tillage and ploughed plots were incubated with dairy slurry (SL) and manure compost (MC) in comparison with calcium ammonium nitrate (CAN) and an unfertilized control (ZERO) for 42 days. N₂O and CO₂ fluxes, ammonium, nitrate, dissolved organic C, and functional gene abundances (16S rRNA gene, nirK, nirS, nosZ, bacterial and archaeal amoA) were regularly monitored. Averaged across all soil samples, N₂O emissions decreased in the order CAN and SL (CAN?=?748.8?±?206.3, SL?=?489.4?±?107.2 μg kg^?1) followed by MC (284.2?±?67.3 μg kg^?1) and ZERO (29.1?±?5.9 μg kg^?1). Highest cumulative N₂O emissions were found in 10–20 cm of the reduced tilled soil in CAN and SL. N₂O fluxes were assigned to ammonium as source in CAN and SL and correlated positively to bacterial amoA abundances. Additionally, nosZ abundances correlated negatively to N₂O fluxes in the organic fertilizer treatments. Soils showed a gradient in soil organic C, 16S rRNA, nirK, and nosZ with greater amounts in the 0–10 than 10–20 cm layer. Abundances of bacterial and archaeal amoA were higher in reduced tilled soil compared to ploughed soils. The study highlights that tillage system induced biophysicochemical stratification impacts net N₂O emissions within the soil profile according to N and C species added during fertilization.     

Cattle trampling alters soil properties and changes soil microbial communities in a Swiss sub-alpine pasture

Stock farming plays an important role in the agriculture of alpine regions although deleterious effects on the soils are most pronounced here. We investigated the effects of cattle trampling on soil physical, chemical and microbial properties in a Swiss sub-alpine pasture. About 10% of the study site was bare of vegetation as a result of repeated cattle trampling and the bulk density of these bare steps was 20% higher than of the soils unaffected by trampling. In the upper 25 cm, soil organic carbon (SOC) concentrations and total SOC stocks were 35% and 20% respectively lower than on the vegetated slope. As compared with the vegetated slope, topsoils of the bare steps featured narrower C:N-ratios and were more enriched in the ¹⁵N isotope, with typical values of deeper soil layers. This indicates that bare soils primarily evolved by erosion and not by a compaction, which might, together with the reduced litter input, explain the lower SOC contents. The abundances of soil microbes, estimated by the concentrations of phospholipid fatty acid (PLFA), were 30% smaller in the bare soils than in the vegetated areas. This depletion was most pronounced for fungi as expressed in the lower concentrations of the fatty acid 18:2ω6.9 (45%) and ergosterol (50%). The lower fungal abundance very likely has negative consequences for the stability of the bare soils, since fungi play an important role in the formation of soil aggregates. In summary, our results show that cattle trampling decreases soil carbon storage and alters soil microbial community structure.     

Stilbene levels in grape cane of different cultivars in southern Chile: determination by HPLC-DAD-MS/MS method

Health benefits of trans-resveratrol and other stilbenes in grapes, must, and wine have been pointed out by numerous authors. Less attention has been paid to the presence of stilbene derivatives in viticultural residues, such as grape canes. The present work reports the first results of a systematic study of stilbene levels in different grape varieties and cultivation areas in Chile, to evaluate their potential as an alternative source of bioactive stilbenes. In all cane samples, the predominant stilbene is trans-resveratrol, followed by ε-viniferin and piceatannol. In canes of Pinot noir up to 5590 ± 172 mg kg(-1) of trans-resveratrol and up to 6915 ± 175 mg kg(-1) of total stilbenes were detected. The observed concentrations of stilbenes in canes of Pinot noir from southern Chile until now are higher than those reported previously for this red variety. However, the highest concentration of total stilbenes observed in the analyzed samples was in the canes of white variety Gewürztraminer with 7857 ± 498 mg kg(-1). Preliminary results indicate that these levels can evolve if canes are left for some months on the vineyard after pruning, observing an increase during the first 2 months and a decrease after this period.     

The highly toxic Aconitum carmichaelii Debeaux as a root vegetable in the Qinling Mountains (Shaanxi, China)

Aconitum spp. are highly toxic due to the presence of aconitine-type alkaloids. Aconitum carmichaelii Debeaux is one of the most important and most studied Chinese medicines. However the scientific literature contains only anecdotal references to the use of A. carmichaelii as a food plant. The aim of the study was to document the traditional alimentary use of the species. Fifty people from three adjacent villages on Mount Taibai of the Qinling range (Shaanxi) were interviewed about the local use of the Aconitum. Most of them eat it on a regular basis every winter. The plant is widely cultivated in the area for food and nearly every family grows it. The tubers are cooked a few times during winter. Usually around 5 kg are prepared at one time and boiled, adding water four times, each time for at least 2 h, over a high flame. People usually eat one bowl a day (ca. 200 g). Respondents claim they eat them for two reasons: they heat the body in winter (they are “hot by nature”) and they are nourishing like other staples.     

A combined hydraulic and toxicological approach to assess re-suspended sediments during simulated flood events—part II: an interdisciplinary experimental methodology

Purpose

Flood events are expected to increase both in intensity and frequency due to climate change in the near future. From an environmental toxicology perspective, there is concern that such flood events could lead to the remobilization of contaminated sediment layers in rivers. The aim of this pilot study was to establish a novel and interdisciplinary framework combining methods of hydrodynamic engineering and ecotoxicological assessment to enable investigation of the potential risks associated with such remobilization events.

Materials and methods

Formulated sediment was prepared according to OECD guideline 218 and spiked with a mixture of four polycyclic aromatic hydrocarbons (phenanthrene, chrysene, pyrene, benzo[a]pyrene) at concentrations of 3.3?C8.3?mg?kg^?1 dry weight. Rainbow trout (Oncorhynchus mykiss) were exposed as test animals to re-suspended sediments in three out of five experiments. The experiments were carried out in an annular flume designed to investigate transport behaviour of fine-grained sediments. Several physicochemical (e.g. pH) and sedimentological (e.g. turbidity) parameters were measured to characterise environmental conditions and erosion behaviour of sediments. Furthermore, exposure concentrations were measured by means of an in vitro assay (7-ethoxyresorufin-o-deethylase (EROD), RTL-W1 cell assay) and chemical analysis.

Results and discussion

Preparation and spiking of large amounts of formulated sediments were feasible but not practical. Successful spiking could be confirmed by the bioanalytical methods with the spiked sediments showing significantly elevated EROD induction compared to control sediments. Conditions within the annular flume remained stable throughout all experiments and were adequate to support rainbow trout. Flood events were successfully simulated, resulting in re-suspension of formulated sediment. Different erosion behaviours of sediments during the simulated flood events were observed and could be associated with changes in microbial composition of sediments due to differences in storage conditions. Therefore, maintaining constant storage conditions of formulated sediments is crucial to enable consistency and comparability among erosion experiments.

Conclusions

This study clearly demonstrated the feasibility of a combined hydro-toxicological approach in support of the investigation of the potential ecotoxicological relevance of sediment re-suspension events. However, based on the results presented here, it is recommended to include additional physicochemical parameters, such as redox potential and conductivity, and to extend the experimental setup to natural sediments and different aquatic organisms. Future studies will use natural sediments containing representative microbial communities and extracellular polymeric substances to enable extrapolation from the annular flume to conditions in natural flowing waters.     

Evidence of plaggen soils in SW Norway

This study aimed at clarifying whether a notable group of soils of the Jæren region, SW Norway, with deep humus‐rich top soils support a man‐made genesis. Four sites were investigated. The soils are characterized by thick top soils of 45, 70, 80, and 90 cm, which are enriched in soil organic matter and often also in artifacts, like fragments of potter's clay, indicating an anthropogenic origin. Soil pH ranges from 5.4 to 6.2 (H₂O) and 4.4 to 5.3 (CaCl₂), respectively. Soil organic C (SOC) contents range from 6.4 to 51.6 g kg^?1 and N contents vary between 0 and 2.9 g kg^?1. Increased P contents of up to 2,924.3 mg kg^?1 total P (P_t) and 1,166.4 mg kg^?1 citric acid‐soluble phosphorus (P_c) in the humus‐rich top soils support the assumption of an anthropogenic influence. Although many characteristics indicate an anthropogenic genesis, one soil lacks the required depth of 50 cm of a plaggen horizon and cannot be classified as Plaggic Anthrosol (WRB) and Plagganthrept (US Soil Taxonomy). As the requirement is 40 cm in the German system, all soils can be classified as Plaggenesch. The formation of these soils is related to human activity aiming at increasing soil fertility and overcoming the need of bedding material, the basic aims of the plaggen management in Europe. Highest P contents ever found for this kind of soils and references from the literature indicate that the formation of the soils in Norway started at Viking time, hence, being older than most other Plaggic Anthrosols.     

Analysis of Flavan-3-ols and procyanidins in food samples by reversed phase high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (RP-HPLC-ESI-MS/MS)

Concentrations of the main dimeric and trimeric procyanidins (PC) and their monomeric constitutive units catechin (CT) and epicatechin (EC) were determined in food samples by using reversed phase high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (RP-HPLC-ESI-MS/MS). In a first step, 12 PCs (PC B1, B2, B3, B4, B5, B6, B7, B8, C1, C2, and A2 and cinnamtannin B1), of which most are not commercially available, were isolated from plant materials or synthesized and purified by a combination of column chromatographic separation techniques with different stationary phases. These PCs in combination with CT and EC were used as standard substances for identification and quantification during the following screening of food samples by RP-HPLC-ESI-MS/MS analysis. The main focus of the newly developed RP-HPLC-ESI-MS/MS method is the compensation of matrix effects by using the echo-peak technique simulating internal standard injection. The suitability of this new method was demonstrated by the determination of recovery rates being 90% or higher. Use of this method allowed the determination of patterns and concentrations of PCs in 55 food samples.