Combined effect of biochar and soil moisture on soil chemical properties and microbial community composition in microplastic-contaminated agricultural soil

Accumulation of microplastics (MPs) in agricultural environments has caused growing concern in recent years because of its detrimental impacts on soil quality, crop productivity and ecosystem function. This study was conducted to assess the impact of biochar on soil chemical and microbial properties in a MP-contaminated soil under two moisture regimes. Soil was contaminated with 1% (w/w) of low-density polyethylene MPs. Four types of standard biochar, that is, oil seed rape (OSR) biochar produced at 550°C (OSR 550) and 700°C (OSR 700) and soft wood pellet (SWP) biochar produced at 550°C (SWP 550) and 700°C (SWP 700), were applied at a rate of 5% (w/w). The control was maintained without MP addition. The samples were incubated in soil with two moisture regimes, that is, at 30% and 70% of the water holding capacity, and the soil chemical and microbiological properties were assessed after 100 days of incubation. OSR biochar application significantly increased soil pH (8.53–8.81) and electrical conductivity (0.51–0.58 dS/m) in both moisture regimes. The effect of biochar application on soil enzyme activity and microbial community composition did not show a clear trend. However, SWP 700 biochar improved soil enzyme activity compared with that of the control and improved bacterial diversity and evenness compared with those of other biochars, which was attributed to the high surface area available for microbial colonization. Low soil moisture content significantly reduced enzyme activity and bacterial richness even with biochar amendment, except for SWP 550 biochar. This study implies the suitability of biochar for improvement of soil quality in MP contaminated soil under both moisture regimes. However, further long-term studies are needed to get a clear understanding on the impact of different types of biochar on MP-contaminated soil.     

农田中的(微)塑料污染:来源、迁移、环境生态效应及防治措施

近年来,继海洋中的微塑料污染受到广泛关注后,土壤微塑料的环境风险逐渐受到重视,有关微塑料对土壤生态环境影响的研究取得了积极进展.本文总结了迄今为止的有关农田土壤中(微)塑料的研究成果和进展,阐明了当前国内外农田微塑料污染现状;详细论述了农田土壤中(微)塑料的来源以及不同源对农田微塑料污染的潜在贡献;对农田微塑料污染现有...     

Microplastics in soil: Impacts and microbial diversity and degradation

Microplastics(MPs) are plastic particles less than 5 mm in size that have become a major environmental pollutant due to their ubiquitous and persistent nature. Microplastic contamination of the aquatic environment has received the most attention so far, whereas the current understanding of MP prevalence and its impacts in the terrestrial environment is largely limited. The MP contamination of soil can cause bioaccumulation and toxicity in terrestrial animals and plants, which can consequently affect human health. This review is aimed towards combining the available information on the occurrence, sources, and effects of MPs on the different aspects of the terrestrial environment and to highlight the limitations in our knowledge regarding the nature and impacts of MPs in soil. The review also highlights microbial degradation of MPs as an advancing research area, with numerous microorganisms being identified as capable of efficiently degrading this persistent contaminant.     

Effect of LDPE microplastics on chemical properties and microbial communities in soil

The accumulation of plastics in the soil ecosystem poses an increasing environmental concern worldwide. However, little is known about the effect of plastic concentrations on soil properties and soil biota. In this study, we investigated the effect of low-density polyethylene (LDPE) microplastics (MPs) on the chemical and microbial properties of agricultural soil using a set of microcosm experiments. The soil was incubated for 100 days with LDPE at concentrations of 0%, 0.1%, 1%, 3%, 5%, and 7% at 25°C with 70% water-holding capacity. Along with soil chemical analysis, we conducted an analysis of soil microbial properties on the first day and again after 100 days of incubation. LDPE concentrations of ≥1% significantly (p < .05) decreased the pH but increased the electrical conductivity of the soil in comparison with the control (0% LDPE at 100 days). Increasing the LDPE concentration did not affect the soil exchangeable cation content or the available Pb concentration. Firmicutes were the most abundant phyla in the soil on the first day, whereas Proteobacteria, Firmicutes and Actinobacteria became dominant in all treatments after 100 days. An increasing LDPE concentration increased the abundance of Actinobacteria and decreased Proteobacteria. Principal component analysis demonstrated that only 7% LDPE was positively correlated with Actinobacteria, indicating that higher concentrations of LDPE contributed to the growth of this phylum. The findings of this study imply that MP contamination could affect soil chemical properties and microbial activity and that these effects primarily depend on MP concentrations in soil.     

Effect of vegetation switch on soil chemical properties

Soil chemical properties were investigated under four types of forest to evaluate the effect of replacement of tree species on soil chemical properties in the north of Japan. Two sites had undergone a vegetation switch around 1960 from broadleaved to coniferous trees (BC) and coniferous to broadleaved trees (CB), while the other two sites had had no vegetation change and carried broadleaved trees (BB) and coniferous trees (CC). Soil samples from the four sites were analyzed for pH (water, H₂O), electrical conductivity (EC), total carbon (C) and nitrogen (N) content, exchangeable cations [Ex. calcium (Ca), magnesium (Mg), potassium (K) and sodium (Na)], inorganic nitrogen (Inorg-N), nitrogen mineralization potential, total phosphorus (P), and available phosphate. Most of the soil chemical properties in both the upper (0–5?cm) and lower (5–10?cm) layers at the BC site had lower values than those at the BB site. Values of soil chemical properties in the upper and lower soil layers were similar at the BC and CC sites. pH, Inorg-N, EC, Ex.Ca and Ex.Mg in the upper layer at the CB site were significantly higher than those at CC site, whereas all soil properties at the CB site except for Inorg-N were similar to those at the BB site. In the lower layer at the CB site, values of soil chemical properties except for the C/N ratio were almost the same as those at the CC site, but lower than those at the BB site. The upper soil layer at sites where a vegetation switch had occurred was affected by the current tree species, whereas in the lower soil layer, the effects differed between the different vegetation switch patterns. At the CB site, where the vegetation switch was from coniferous to broadleaved trees, the soil chemical properties in the lower layer remained similar to those at the coniferous site (CC) 50 years after the vegetation switch, while changes in soil properties have occurred following the switch from broadleaved to coniferous trees. The change in soil nutrient content by vegetation switch was considerably affected by change in not only litter quality but also composition of earthworm community. In particular, a combination of epigeic and endogeic earthworms exhibited important roles for nutrient dynamics to the deeper soil layer.     

用最小可检测差异技术评估耕作方式对土壤C固定的影响

Three long-term field trials in humid regions of Canada and the USA were used to evaluate the influence of soil depth and sample numbers on soil organic carbon （SOC） sequestration in no-tillage （NT） and moldboard plow （MP） corn （Zea mays L.） and soybean （Glycine max L.） production systems. The first trial was conducted on a Maryhill silt loam （Typic Hapludalf） at Elora, Ontario, Canada, the second on a Brookston clay loam （Typic Argiaquoll） at Woodslee, Ontario, Canada, and the third on a Thorp silt loam （Argiaquic Argialboll） at Urbana, Illinois, USA. No-tillage led to significantly higher SOC concentrations in the top 5 cm compared to MP at all 3 sites. However, NT resulted in significantly lower SOC in sub-surface soils as compared to MP at Woodslee （10-20 cm, P =0.01） and Urbana （20-30 cm, P 〈 0.10）. No-tillage had significantly more SOC storage than MP at the Elora site （3.3 Mg C ha^-1） and at the Woodslee site （6.2 Mg C ha^-1） on an equivalent mass basis （1 350 Mg ha^-1 soil equivalent mass）. Similarly, NT had greater SOC storage than MP at the Urbana site （2.7 Mg C ha^-1） on an equivalent mass basis of 675 Mg ha^-1 soil. However, these differences disappeared when the entire plow layer was evaluated for both the Woodslee and Urbana sites as a result of the higher SOC concentrations in MP than in NT at depth. Using the minimum detectable difference technique, we observed that up to 1 500 soil sample per tillage treatment comparison will have to be collected and analyzed for the Elora and Woodslee sites and over 40 soil samples per tillage treatment comparison for the Urbana to statistically separate significant differences in the SOC contents of sub-plow depth soils. Therefore, it is impracticable, and at the least prohibitively expensive, to detect tillage-induced differences in soil C beyond the plow layer in various soils.     

Microplastics in agroecosystems: A review of effects on soil biota and key soil functions

Contamination of soils in agroecosystems with microplastics (MPs) is of increasing concern. The contamination of the environment/farmland soils with MPs (1 µm to 5 mm sized particles) and nanoplastics (NPs; <1 µm sized particles) is causing numerous effects on ecological soil functions and human health. MPs enter the soil via several sources, either from intentional plastic use (e.g., plastic mulch, plastic greenhouses, plastic-coated products) or indirectly from the input of sewage sludge, compost, or irrigation water that is contaminated with plastic. Once in the soil, plastic debris can have various impacts such as changes in soil functions and physicochemical properties and it affects soil organisms due to its toxic behavior. This review paper describes the different effects of plastic waste to understand the consequences for agricultural productivity. Furthermore, we identify knowledge gaps and highlight the required approaches, indicating future research directions on sources, transport, and fate of MPs in soils to improve our understanding of various unspecified abiotic and biotic impacts of MP pollution in agroecosystems.     

Impact of Biomass Combustion on Urban Fine Particulate Matter in Central and Northern Europe

The distribution of nonylphenol ethoxylates (NPEOn) and their derivatives of nonylphenol (NP) and nonylphenoxy ethoxy acetic acids (NPEnC) in the sediments of a relatively closed freshwater reservoir was investigated using sediment layers sliced from undisturbed sediment cores collected with a gravity core sampler at three sampling sites (St. 1, St. 2 and St. 3) along the water flow direction. The relationships between the bound content of these compounds and the sediment organic matter as well as the likely transformation pathways were evaluated. The total content of NPEOn (n?=?1–15) fell in 84.6–336.5, 59.9–135.5 and 77.0–623.4 μg/kg-dry for all sliced layers at St.1, St.2 and St.3, respectively, with the content of individual NPEOn species showing a general decreasing trend with the attached molar number of the ethoxy (EO) chain. Compared to each detected NPEOn species, the bound content of NP was much higher, falling in 73.2–248.4, 79.9–358.2 and 25.5–1,988.4 μg/kg-dry at St. 1, St. 2 and St. 3, respectively. A general increasing trend of the NP content along the water flow direction of the reservoir was revealed. NPEnC (n?=?1–10) varied in 1.93–4.12, 2.85–9.84 and 1.05–19.1 μg/kg-dry for sediment at the respective site of St. 1, St. 2 and St. 3, with the averaged values at these sites (2.91, 4.71 and 6.72 μg/kg-dry) showing an increasing trend from the upstream to the downstream. For NPEnC, a parametric trend of increases in the content of NPE₁C, NPE₂C and NPE₃C with the bound sediment organic matter (9.06–11.8%) seemed to be existent. Furthermore, the computed magnitudes of NPEO_1–2/NPEO_1–15, NP/NPEO_1–15 and NPEC_1–10/NPEO_1–15 suggested that non-oxidative hydrolytic transformation was probably prevailing within the sedimented mud phase of the reservoir, with the oxidative hydrolytic transformation pathway being less involved.     

New classification systems for tropical organic-rich deposits based on studies of the Tasek Bera Basin,Malaysia

Most schemes in common use for field and laboratory classification of peats were developed in boreal and humid temperate regions and do not recognize the distinctive features and specific uses of tropical peats, such as those of the Tasek Bera Basin in tropical Peninsular Malaysia. The important aspects of peat texture (morphology of constituents and their arrangement) and laboratory ash content (residue after ignition) need modification to be valuable for classifying these and other tropical peat deposits. In the Tasek Bera Basin, most of the deposits would not be considered as peat according to some classification schemes, even though most have C contents >25%. We propose a new three-group (fibric, hemic, sapric) field texture classification applicable to tropical organic deposits, which is similar to the system of the US Soil Taxonomy. The classification is based on the following factors: (1) visual examination of the morphology of the peat constituents (texture); and (2) estimates of fiber content and matrix (finest fraction of peat consisting of highly humified organic matter and inorganic material). The classification is applicable to all organic deposits with <65% ash (i.e., >35% loss on ignition). We also present a new laboratory classification of organic soils based on ash and C content. The US Soil Taxonomy classifies organic soils as having more than 12–18% organic C, depending on clay content. Ash content and these limits for organic soils allow the discrimination of four main groups: peat, muck, organic-rich soil/sediment and mineral soil/sediment. Peat is defined as having an ash content of 0–55%, muck 55–65%, organic-rich soil/sediment 65–80% and mineral soil/sediment 80–100%. The peat class is further subdivided into very low ash (0–5%), low ash (5–15%), medium ash (15–25%), high ash (25–40%) and very high ash (40–55%) subclasses.     

红壤坡地新开发果园土壤有机碳迁移对不同管理措施的响应

为探究在南方红壤区不同管理措施对于新开发果园土壤有机碳迁移的影响,以典型红壤坡地柑橘园(建园2年)为研究对象,监测评估自然降雨背景下清耕(CB)、稻草全覆盖(CS)、萝卜花生轮作(CRP)、三叶草条带覆盖(CCS)、三叶草全覆盖(CC)和苔藓覆盖(CT)6种管理措施对开发初期果园水土流失和土壤有机碳迁移的影响。结果表明:(1)6种管理措施CB、CS、CRP、CCS、CC和CT的径流量分别为7.88,4.45,4.64,3.24,3.25,4.70 m³,与CB相比,CS、CRP、CCS、CC和CT措施下截流效益分别为43.51%,41.10%,58.94%,58.82%,40.38%,产沙量分别为71.35,21.27,31.03,14.24,14.18,35.05 kg,产沙量与CB相比分别减少70.18%,56.51%,80.04%,80.13%,50.87%;(2)泥沙有机碳流失强度分别为CB(20.75 g/m²),CS(4.78 g/m²),CRP(8.68 g/m²),CCS(3.52 g/m²),CC(3.38 g/m²),CT(9.94 g/m²),相比于对照组CB分别减少76.94%,58.16%,83.01%,83.71%,52.11%;(3)泥沙有机碳和DOC流失强度均与径流量呈显著正相关关系(R²分别为0.412和0.419)。地面管理措施主要通过调控地表径流的产生来影响红壤坡地新开发果园土壤有机碳的迁移。综合来看,三叶草条带覆盖和全覆盖在抑制土壤侵蚀和土壤有机碳迁移损失方面效果较明显。研究结果可为南方红壤区新开发果园水土流失和土壤有机碳迁移损失的防控提供科学依据。     

Encapsulation of the ethylene inhibitor 1-Methylcyclopropene by cucurbit[6]uril

1-Methylcyclopropene (1-MCP) is an excellent safe and commercially available ethylene antagonist for the preservation of horticultural products. However 1-MCP has to be stored in absorbents due to its gaseous and unstable characteristics. In this paper cucurbit[6]uril (CB[6]) was used as the absorbent to encapsulate 1-MCP, and the resultant inclusion complex was characterized by IR, powder X-ray diffraction, thermal analysis, and fluorescent spectra. The effects of encapsulation conditions on the formation of inclusion complex were also investigated. The amount of 1-MCP encapsulated by CB[6] was about 4.5% by weight when the initial concentration of 1-MCP, encapsulation temperature, CB[6] concentration, and encapsulation time were set at 75 mL/L, 20 °C, 30 mM, and 8 h, respectively. Furthermore, the release of 1-MCP from the complex can be realized with different solutions such as sodium bicarbonate, benzoic acid, and distilled water. CB[6] can be used as an excellent absorbent for encapsulation of 1-MCP.     

Response of organic matter to reduced tillage and animal manure in a temperate loamy soil

The impacts of tillage and organic fertilization on soil organic matter (SOM) are highly variable and still unpredictable, and their interactions need to be investigated under various soil, climate and cropping system conditions. Our work examined the effect of reduced tillage and animal manure on SOM stocks and quality in the 0–40 cm layer of a loamy soil under mixed cropping system and humid temperate climate. The soil organic carbon (SOC) and N stocks, particulate organic matter (POM), and C and N mineralization potential (301 days at 15 °C) were measured in a 8‐yr‐old split‐plot field trial, including three tillage treatments [mouldboard ploughing (MP), shallow tillage (ST), no tillage (NT)] and two fertilization treatments [mineral (M), poultry manure 2.2 t/ha/yr C (O)]. No statistically significant interactive effects of tillage and fertilization were measured except on C mineralization. NT and ST showed greater SOC stocks (41.2 and 39.7 t/ha C) than MP (37.1 t/ha C) in the 0–15 cm increment, while no statistical differences were observed at a greater depth. N stocks exhibited similar distribution patterns with regard to tillage effect. Animal manure, applied at a rate representative of typical field application rates, had a smaller impact on SOC and N stocks than tillage. The mean SOC and N stocks were higher under O than M, but the differences were statistically significant only in the 0–5 cm increment. MP showed lower C‐POM stocks than NT and ST in the 0–5 cm increment, whereas greater C‐POM stocks were measured under MP than under NT or under ST in the 20–25 cm increment. Organic fertilization had no impact on C‐POM or N‐POM stocks. In the 0–25 cm increment, NT showed a lower C and N mineralization potential than MP. Our work shows that the sensitivity of SOM to reduced tillage for the whole soil profile can be relatively small in a loamy soil, under humid‐temperate climate. However, POM was particularly sensitive to the differential effects of tillage practices with depth, and indicative of differentiation in total SOM distribution in the soil profile.     

Soybean expansion impacts on soil organic matter in the eastern region of the Maranhão State (Northeastern Brazil)

Recently, the eastern region of the Maranhão state (Northeastern Brazil) became a hotspot of land-use change (LUC) directly from native vegetation to soybean cultivation, but due to the soil characteristics, LUC has caused substantial soil organic carbon (SOC) and nitrogen depletion. Therefore, we quantified these impacts arising from two factors: (i) different timeframes after LUC and (ii) contrasting soil management practices. For the first study, soil samples (0–30 cm; six replicates) were taken on soybean fields year one, year eight and 15 years after LUC. It the second study, another area was sampled, of which part was managed under no-tillage (NT) and the other using a mouldboard plough (MP). For both studies, native vegetation (NV) was sampled as the control. NV stored about 50 Mg of carbon (C) ha⁻¹; but LUC reduced C stocks by 35% (after 8 and 15 years); moreover, labile-C decreased between 20% and 45%, while, microbial-C decreased between 20% and 60%, considering the interval between year one and 15 years. Regarding soil management, the MP did not cause differences on C stock (24 Mg C ha⁻¹) in comparison to NT; however, both labile-C and microbial-C decreased by 15% to NT, while, decreased by 40% to MP. These results lead us to believe that, since LUC is inevitable, we suggested the adoption of the best agricultural management practices, in order to preserve/increase the SOC, reducing the impacts on GHG emissions and, thus, achieving sustainability and profitability.     

Atmospheric dust in modern soil on aeolian sandstone,Colorado Plateau (USA): Variation with landscape position and contribution to potential plant nutrients

Rock-derived nutrients in soils originate from both local bedrock and atmospheric dust, including dust from far-distant sources. Distinction between fine particles derived from local bedrock and from dust provides better understanding of the landscape-scale distribution and abundance of soil nutrients. Sandy surficial deposits over dominantly sandstone substrates, covering vast upland areas of the central Colorado Plateau, typically contain 5–40% silt plus clay, depending on geomorphic setting and slope (excluding drainages and depressions). Aeolian dust in these deposits is indicated by the presence of titanium-bearing magnetite grains that are absent in the sedimentary rocks of the region. Thus, contents of far-traveled aeolian dust can be estimated from magnetic properties that primarily reflect magnetite content, such as isothermal remanent magnetization (IRM). Isothermal remanent magnetization was measured on bulk sediment samples taken along two transects in surficial sediment down gentle slopes away from sandstone headwalls. One transect was in undisturbed surficial sediment, the other in a setting that was grazed by domestic livestock until 1974.Calculation of far-traveled dust contents of the surficial deposits is based on measurements of the magnetic properties of rock, surficial deposits, and modern dust using a binary mixing model. At the undisturbed site, IRM-based calculations show a systematic down-slope increase in aeolian dust (ranging from 2% to 18% of the surface soil mass), similar to the down-slope increase in total fines (18–39% of surface soil mass). A combination of winnowing by wind during the past and down-slope movement of sediment likely accounts for the modern distribution of aeolian dust and associated nutrients. At the previously grazed site, dust also increases down slope (5–11%) in sediment with corresponding abundances of 13–25% fines. Estimates of the contributions of aeolian dust to the total soil nutrients range widely, depending on assumptions about grain-size partitioning of potential nutrients in weathered bedrock. Nevertheless, aeolian dust is important for this setting, contributing roughly 40–80% of the rock-derived nutrient stocks (P, K, Na, Mn, Zn, and Fe) in uppermost soil over most of the sampled slope at the undisturbed site, which shows no evidence of recent wind erosion.     

Oxidation of skeletal muscle myofibrillar proteins in oil-in-water emulsions: interaction with lipids and effect of selected phenolic compounds

The effect of selected phenolic compounds, namely, gallic acid, cyanidin-3-glucoside, (+)-epicatechin, chlorogenic acid, genistein and rutin (50 and 200 microM), and alpha-tocopherol (50 microM) against the oxidation of oil-in-water emulsions (37 degrees C/10 days) containing 1% myofibrillar proteins (MPs), was investigated. Emulsions containing 1% bovine serum albumin (BSA) were also prepared for comparative purposes. Protein oxidation was assessed by measuring the loss of natural tryptophan fluorescence and the protein carbonyl gain by using fluorescence spectroscopy. Lipid oxidation was concurrently analyzed by measuring the increase of conjugated dienes (CDs) and hexanal. Proteins inhibited lipid oxidation in oil-in-water emulsions, and MPs showed a more intense antioxidant activity than BSA. MPs were also more resistant to oxidative deterioration than BSA. The different antioxidant capacity of MPs and BSA and their susceptibility to suffer oxidative reactions might be derived from their different amino acid composition and three-dimensional structures. The addition of the phenolic compounds resulted in a variety of effects, including both antioxidant and pro-oxidant effects. Gallic acid, cyanidin-3-glucoside, and genistein were the most efficient inhibitors of lipid and protein oxidation. The chemical structure of the phenolic compounds as well as the nature and conformation of the proteins were greatly influential on the overall effect against oxidative reactions.     

The significance of various sediment magnetic mineral fractions for tracing sediment sources in Killimicat Creek

The mineral magnetic properties of sediment are increasingly being used to determine the sources of sediment, and associated nutrients and contaminants in drainage basins. This study was undertaken to measure the relative contributions of the magnetic mineral components in sediment (i.e., components associated with surface bound Fe, the heavy mineral fraction, and as inclusions in particles) to determine the extent to which they represent the bulk of the sediment. Deposited channel sediment samples from the tributaries and downstream reach at the first major confluence in the headwaters of Killimicat Creek, New South Wales, were sieved to separate 6 particle size fractions, and the mineral magnetic properties measured to determine the relative contribution of sediment from the smaller tributary basin. The finest sand component (63–125 μm) was then separated into light and heavy mineral fractions, and magnetic measurements made on each fraction. Magnetic parameter data from the 63–125 μm fraction, measured before density separation, show a dominance of sediment (70±12%) derived from the smaller tributary basin. Measurements of the light sediment fraction give a similar result (73±13%). The proportion of the heavy mineral fraction delivered from the smaller tributary is 78±38%. The light mineral fraction of all of the samples were treated with HCl to remove surface bound Fe, and subsequent magnetic measurements show that 41–94% of the mass specific magnetic susceptibility is attributable to magnetic minerals associated with surface bound Fe. The heavy mineral component, while <4% by weight of the 63–125 μm fraction, contributes 5–40% of the total magnetic susceptibility. The results show that most of the magnetic mineral component (>60%) is associated with sediment particles, rather than the discrete heavy mineral component.     

Effect of Wheat Bran Fiber and Bran Particle Size on Fat and Fiber Digestibility and Gastrointestinal Tract Measurements in the Rat

The effect of wheat bran (AACC hard red) and bran particle size on fat and fiber digestibility and gastrointestinal tract measurements were investigated with diets containing 5.7–10.7% dietary fiber. Fifty‐six male weanling Sprague‐Dawley rats were randomly assigned to four diets containing 5% cellulose (C5); 10.5% cellulose (C10); 21.5% coarse (2 mm) wheat bran (CB); or 22.2% fine (0.5 mm) wheat bran (FB) in a sixweek study. Dietary fiber digestibilities were significantly different (P < 0.05) among treatment diets (CB > FB > C5 > C10) but there was no effect in fat digestibility among treatments. High‐fiber diets fed to rats resulted in significantly greater wet and dry fecal weights than low‐fiber diets. Bran diets resulted in significantly higher fecal moisture than cellulose diets. Cecum lengths increased significantly with bran diets compared with cellulose diets. The CB diet resulted in significantly higher stomach weights than with cellulose diets. Stomachs were heavier and cecal lengths were greater with bran diets than with cellulose diets; however, a high‐cellulose diet resulted in increased colon weight. Except for higher fiber digestibility of coarse bran, bran particle size had no significant effects. Healthful effects of wheat bran may be associated with gastrointestinal morphology and function. Fecal bulking and decreased intestinal transit time can prevent constipation and may dilute or reduce absorption of toxic or carcinogenic metabolites, thus improving gastrointestinal health and lowering the risk of tumor development and cancer.     

Methyl jasmonate reduces chilling injury and maintains postharvest quality of mango fruit

Exposure of mango (Mangifera indica cv. Tommy Atkins) fruit to methyl jasmonate (MJ) vapors (10(-)(4) M) for 24 h at 25 degrees C reduced chilling injury during subsequent storage for 21 days at 7 degrees C and after 5 days of shelf life at 20 degrees C. The chilling tolerance induced by MJ was positively correlated with the reduction in the percent ion leakage of mango tissue. The overall quality of MJ-treated fruit was also better than that of control fruit. MJ treatment increased the total soluble solids but did not affect titratable acidity or pH. MJ also did not change the normal climacteric rise in respiration, water loss, and softening rates. The efficacy of MJ to reduce chilling injury and decay of mango could be related to the tolerance induced at low temperature. It was concluded that MJ treatment may prevent chilling injury symptoms of mango without altering the ripening process.     

Buried paleosols of the Upper Paleolithic multilayered site Kostenki-1

The morphology and chemical and physicochemical properties of paleosols buried at the Upper Paleolithic multilayered site Kostenki-1 in Kostenki–Borshchevo district of Voronezh oblast were studied. Four in situ paleosols formed 20–40(45) ka ago were separated in the archaeological excavation. Together with the surface soils, they characterized two different epochs of pedogenesis—the interstadial and interglacial (Holocene) epochs—and three shorter cycles of pedogenesis. The traces of human occupation in the studied hollow in the Late Paleolithic were found in the layers corresponding to the interstadial epoch. The buried paleosols had a simple horizonation: A(W)–C. A shallow thickness of the soil profiles could be due to relatively short periods of pedogenesis and to the shallow embedding by the carbonate geochemical barrier. The degree of the organic matter humification in the paleosols varied from 0.6 to 1.5, which corresponded to the mean duration of the period of biological activity of 60 to 150 days per year characterizing the climatic conditions of the tundra, taiga, forest-steppe, and steppe natural zones. In the excavation Kostenki-1 (2004–2005), soil–sediment sequences composed of five series of lithological layers with soil layers on top of them were found. Their deposition proceeded in two phases—the water phase and the aerial phase—that predetermined the morphology and composition of the soil–sediment sequences. The history of sediment accumulation in the studied hollow consisted of five stages. Similar morphologies and compositions of the soil–sediment sequences corresponding to these stages attest to the cyclic pattern of their development. The stages of sedimentation and soil formation corresponded to cyclic climate fluctuations with changes in the temperature and moisture conditions. A comparative analysis of the morphology and properties of the paleosols and soil–sediment sequences made it possible to characterize the environmental conditions of ancient humans and the dynamics of the climate during the past 50 ka.     

Impact of organic inputs on wettability characteristics and structural stability in silty vineyard topsoil

Organic inputs were used for 10 years on a French vineyard topsoil to improve structural stability and thus to protect against erosion. The three types of organic inputs (mulches) included: conifer compost, CC (100 m³ ha^?1 every 3 years); conifer bark, CB (300 m³ ha^?1 every 5 years); and cereal straw, S (10 t ha^?1 every 2 years). The other two types of organic inputs were cover crops of clover (C) and fescue (F). The impacts of these organic inputs on soil organic carbon (SOC) content, wettability (capillary rise and X‐ray photoelectron spectroscopy (XPS)) and structural stability were studied. The SOC content was twice as large in the CC, C and F topsoils (SOC content of 2.56–3.24%) as in the reference (R) topsoil (SOC content of 1.39%). Both apparent contact angle (θ) and surface OH:C mass ratio indicated that the R and S topsoils were hydrophilic (θ of 27.4–33.4°, surface OH:C ratio of 3.20–4.41), whereas the CB, C and F topsoils were partially hydrophobic (θ of 69.1–79.8°, surface OH:C ratio of 1.36–2.86), and the CC topsoil had intermediate values (θ of 46.9°, surface OH:C ratio of 2.43–2.81). Moreover, the greater the θ value, the smaller the water sorptivity value and the greater the proportion of water‐stable aggregates, Ag_w. The increase in SOC content had beneficial effects on Ag_w, particularly for the partially hydrophobic C and F topsoils (Ag_w of 22.3–44.5%) against the hydrophilic R and S topsoils (Ag_w of 8.2–12.7%). Development of hydrophobicity, correlated with the decrease in the surface OH:C ratio and the increase in the C–O, C–N proportion on surface C, should be attributed to humified organic matter or/and to plant and microbial polysaccharides. As the XPS and aggregate stability data describe soil physical processes at small scales (nm to mm), we suggest an experimental and modelling framework for upscaling these results for practical improvement and management of vineyard soils.