Site disturbance effects on a clay soil under radiata pine

Timber harvesting of forested lands can cause impacts which reduce the long-term productivity of the soil. This study examined long-term effects of timber harvesting on soil morphology, soil solutions and clay mineral stability. A disturbance study established in 1981 an Ultisol located in the North Island of New Zealand was examined in 1990. Disturbance treatments were installed following cable logging of radiata pine (Pinus radiata D. Don); treatments consisted of no disturbance (UN), O horizon removed (OR), and O and A horizons removed with compaction of the Bt1/A horizon (OARHC). The morphology of the A and Bt1/A horizons of the OR treatment showed little difference from the UN treatment. Soil solutions were collected using centrifugation and soil mineralogy determined. Soil solutions of the O horizon had nutrient concentrations that were approximately 10 times greater than that of the mineral horizons, indicating that nutrient availability would be reduced by reduced by removal of this horizon during harvesting. Soil solutions of the Bt1/A horizon showed substantially lower nutrient concentrations in the OARHC treatment compared to the UN and OR treatment, at 9-years after treatment. Stability diagrams of soil solutions for clay minerals of the soil showed that smectite was unstable and weatherable with the highest disturbance treatment, but was stable in the no and low disturbance treatment. No disturbance effects were evident in the stability of iron minerals. Results suggest that this soil is capable of returning to pre-disturbance conditions well-within a rotation period when disturbance is limited, but that recovery with the highest disturbance treatment could take substantially longer. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

Influence of compaction from wheel traffic and tillage on arbuscular mycorrhizae infection and nutrient uptake by Zea mays

Interactive effects of seven years of compaction due to wheel traffic and tillage on root density, formation of arbuscular mycorrhizae, above-ground biomass, nutrient uptake and yield of corn (Zea mays L.) were measured on a coastal plain soil in eastern Alabama, USA. Tillage and soil compaction treatments initiated in 1987 were: 1) soil compaction from tractor traffic with conventional tillage (C,CT), 2) no soil compaction from tractor traffic with conventional tillage (NC,CT), 3) soil compaction from tractor traffic with no-tillage (C,NT), and, 4) no soil compaction from tractor traffic with no-tillage (NC,NT). The study was arranged as a split plot design with compaction from wheel traffic as main plots and tillage as subplots. The experiment had four replications. In May (49 days after planting) and June, (79 days after planting), root biomass and root biomass infected with arbuscular mycorrhizae was higher in treatments that received the NC,NT treatment than the other three treatments. In June and July (109 days after planting), corn plants that received C,CT treatment had less above-ground biomass, root biomass and root biomass infected with mycorrhizae than the other three treatments. Within compacted treatments, plants that received no-tillage had greater root biomass and root biomass infected with mycorrhizae in May and June than plants that received conventional tillage. Corn plants in no-tillage treatments had higher root biomass and root biomass infected with mycorrhizae than those in conventional tillage. After 7 years of treatment on a sandy Southeastern soil, the interactive effects of tillage and compaction from wheel traffic reduced root biomass and root biomass infected with mycorrhizae but did not affect plant nutrient concentration and yield. ei]J H Graham     

Availability and uptake of inorganic nitrogen in a mixed old-growth coniferous forest

Old-growth forest stands of mixed species composition provide the opportunity to study species-specific influences on soil properties. We monitored rates of nitrogen mineralization, nitrification and an index of ammonium and nitrate uptake in a mixed old-growth stand of Douglas-fir (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla) and western redcedar (Thuja plicata) over a two-year period. Litter and mineral soil (0–10-cm depth) were sampled adjacent to ten large trees of each species. After initial characterization of litter and soil, buried bags were incubated in both layers for ca. 2-month intervals. Soil and litter pH was lowest near western hemlocks. Nitrification, nitrate concentrations, and percent uptake as nitrate differed among the tree species; rates were highest near western redcedars. For all species, percent nitrification and nitrate uptake rate were higher in soil than in litter. The results indicate species-specific effects on ammonium and nitrate production and uptake within this forest type.The research described in this article has been funded in part by the US Environmental Protection Agency. This document has been prepared at the EPA Environmental Research Laboratory in Corvallis, Oregon, through Contract No. 68-C8-0006 to ManTech Environmental Technology, Inc. It has been subjected to the Agency's peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.The research described in this article has been funded in part by the US Environmental Protection Agency. This document has been prepared at the EPA Environmental Research Laboratory in Corvallis, Oregon, through Contract No. 68-C8-0006 to ManTech Environmental Technology, Inc. It has been subjected to the Agency's peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

A comparison between computer modeled bioaerosol dispersion and a bioaerosol field spray event

The observed deposition pattern from a field spray ofBacillus subtilus var.niger spores is compared with that of a computer simulated bioaerosol particle dispersion model. Using the same meteorological conditions as the field spray, the model produced a bioaerosol deposition pattern estimated to be reasonably similar (R ²=0.66) to the observed field pattern. Reasons for the differences between the deposition patterns are discussed. The comparison indicates that viable airborne particle deposition models may, with future testing, be useful tools for predicting near source aerial microbial dispersal and deposition. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

秸秆覆盖免耕土壤细菌和真菌生物量与活性的研究

土壤微生物生物量在土壤生态系统中具有非常重要的作用。大量的试验研究表明 ,土壤微生物生物量是植物营养元素的一个重要的源与库 ,生物量对土壤养分的调控作用 ,已经成为土壤培肥、耕作制度改革和作物栽培实践中的重要理论依据之一。自从Jenkinson提出了测定土壤微生物量的原理和概念以来 ,Jenkinson和 Powlson提出了测定微生物生物量的方法[16] ,Van De Werf和 Verstraete提出了土壤微生物生物量可以分为全微生物量和活动微生物量[10 ] ,Anderson和 Domsch提出了生物量与生物活性中细菌与真菌的比例为 2 2 /78% [8]。虽然生物量的研…     

Biofilm formation by bacterial contaminants of fuel ethanol production

Commercial fuel ethanol production facilities were previously shown to have characteristic populations of bacterial contaminants which reduce product yield and are difficult to eradicate. Bacterial contaminants were found, for the first time, to form biofilms under laboratory conditions. Fermentor samples from a commercial fuel ethanol production facility were used to inoculate a biofilm reactor and purified bacterial isolates were identified. Biofilms were composed of many of the same species present in production samples, with lactic acid bacteria predominating. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Co-production of Schizophyllan and Arabinoxylan from Corn Fiber

Schizophyllum commune strain ATCC 38548 grew well on a medium containing alkaline H₂O₂-pretreated corn fiber as a sole carbon source, and clarified the culture medium within 7 days. The strain preferentially utilized the starch component of corn fiber for growth and production of schizophyllan. Culture supernatants contained approx. 50 mg schizophyllan and 200 mg arabinoxylan per g corn fiber. These polysaccharides were recovered separately by differential precipitation with ethanol. USDA - Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. Revisions requested 29 November 2005; Revisions received 24 January 2006     

Diversity of arbuscular mycorrhizal fungi along a sand dune stabilization gradient: A case study at Praia da Joaquina, Ilha de Santa Catarina, South Brazil

Species diversity of arbuscular mycorrhizal fungi (AMF) was assessed along a dune stabilization gradient (embryonic dune, foredune and fixed dune) at Praia da Joaquina, Ilha de Santa Catarina. The dunes were chosen as a case study to assess whether diversity and mycorrhizal inoculum potential (MIP) increase along the gradient. Ten soil samples were collected from each stage and pooled, and then six 100-g soil sub-samples were taken to identify and enumerate spores. Twelve AMF species were detected, and all three families in Glomales were represented. Gigasporaceae species dominated the embryonic dune, while Glomaceae species dominated the fixed dune. Total spore numbers and richness increased as the dunes became more stabilized. However, indices of Margalef, Simpson and Shannon reached maximal values at different stages, suggesting that species abundance was different among stages. In both embryonic and fixed dunes, species abundance data fit the broken stick model, while in the foredune the log series model best described the data. The MIP followed spore numbers and increased along the gradient, suggesting that spores are important in initiating root colonization in this system. Relationships between edaphic factors and functional roles of Glomales families as determinants of AMF distribution are discussed. This document was subjected to peer and administrative reviews of the U.S. EPA at the National Health and Environmental Effects Research Laboratory, Western Ecology Division, and was approved for publication. Mention of trade names or commercial products in this paper does not constitute endorsement or recommendation of use.     

Immunogenicity of a novel, bivalent, plant-based oral vaccine against hepatitis B and human immunodeficiency viruses

A synthetic chimeric gene, TBI-HBS, encoding the immunogenic ENV and GAG epitopes of human immunodeficiency virus (HIV-1) and the surface protein antigen (HBsAg) of hepatitis B virus (HBV), was expressed in tomato plants. Tomato fruits containing the TBI-HBS antigen were fed to experimental mice and, on days 14 and 28 post-feeding, high levels of HIV- and HBV-specific antibodies were present in the serum and feces of the test animals. Intraperitoneal injection of a DNA vaccine directing synthesis of the same TBI-HBsAg antigen boosted the antibody response to HIV in the blood serum; however, it had no effect on the high level of antibodies produced to HBV.Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

保护性耕作对土壤微生物量及活性的影响

研究保护性耕作对土壤微生物特性的影响对于土壤管理具有重要意义。试验研究了保护性耕作对麦田土壤微生物量碳、活跃微生物量、土壤呼吸、呼吸商的影响。前3项采用的方法分别是:基质诱导呼吸法、呼吸曲线数学分析法和CO2释放量法。结果表明,保护性耕作土壤微生物量碳0～10cm土层大于10～20cm土层,而常规耕作两土层间无明显差异。秸秆还田在播种前、越冬期和起身期能显著提高土壤微生物量碳,而开花期和收获期则降低土壤微生物量碳。少耕还田10～20cm土层微生物具有较强的养分调控作用。保护性耕作利于0～10cm土层活跃微生物量的提高。秸秆还田和保护性耕作在耕作作业初期(越冬期和起身期)能增强土壤呼吸速率;在耕作作业后期(开花期和收获期)能显著降低土壤呼吸速率。免耕秸秆覆盖在10～20cm土层呼吸商较高,而常规耕作无秸秆还田在0～10cm土层呼吸商较高。土壤微生物量碳和呼吸商是衡量土壤微生物特性的重要指标。     

Cellulose utilization in forest litter and soil: identification of bacterial and fungal decomposers

Organic matter decomposition in the globally widespread coniferous forests has an important role in the carbon cycle, and cellulose decomposition is especially important in this respect because cellulose is the most abundant polysaccharide in plant litter. Cellulose decomposition was 10 times faster in the fungi-dominated litter of Picea abies forest than in the bacteria-dominated soil. In the soil, the added (13)C-labelled cellulose was the main source of microbial respiration and was preferentially accumulated in the fungal biomass and cellulose induced fungal proliferation. In contrast, in the litter, bacterial biomass showed higher labelling after (13)C-cellulose addition and bacterial biomass increased. While 80% of the total community was represented by 104-106 bacterial and 33-59 fungal operational taxonomic units (OTUs), 80% of the cellulolytic communities of bacteria and fungi were only composed of 8-18 highly abundant OTUs. Both the total and (13)C-labelled communities differed substantially between the litter and soil. Cellulolytic bacteria in the acidic topsoil included Betaproteobacteria, Bacteroidetes and Acidobacteria, whereas these typically found in neutral soils were absent. Most fungal cellulose decomposers belonged to Ascomycota; cellulolytic Basidiomycota were mainly represented by the yeasts Trichosporon and Cryptococcus. Several bacteria and fungi demonstrated here to derive their carbon from cellulose were previously not recognized as cellulolytic.     

Isolation, characterization and optimization of culture parameters for production of an alkaline protease isolated from Aspergillus tamarii

Aspergillus tamarii expresses an extracellular alkaline protease that we show to be effective in removing hair from cattle hide. Large quantities of the enzyme will be required for the optimization of the enzymatic dehairing process so the growth conditions for maximum protease expression by A. tamarii were optimized for both solid-state culture on wheat bran and for broth culture. Optimal protease expression occurred, for both cultural media, at initial pH 9; the culture was incubated at 30 °C for 96 h using a 5% inoculum. The crude enzyme was isolated, purified and characterized using MALDI TOF TOF. The alkaline protease was homologous to the alkaline protease expressed by Aspergillus viridinutans. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Reproductive and developmental responses in the self-fertilizing fish,Rivulus marmoratus,induced by the plasticizer,di-n-butylphthalate

Synopsis Specialized life-history attributes of the cyprinodontiform fish, Rivulus marmoratus, allow continuous life cycle testing to reveal effects of chemicals or environmental stresses upon fertilization, fecundity, egg viability, embryonic development, sex ratios, frequency of growth or skeletal anomalies, as well as other biological markers. This study reports responses in fecundity, viability of embryos, and skeletal anomalies during and after exposure of parental fish to the plasticizer, di-n-butylphthalate (DBP). Skeletal anomalies among offspring were classified as mild, moderate, or severe compared with non-deformed normal offspring. The frequency of skeletal anomalies increased from 4% (all categories combined) in controls, to 10% and 19% of the offspring from adults exposed to 1 and 2 mg I^-1 DBP, respectively. DBP treatment was conducted over a 21 week interval, followed by a 9 week post-treatment observation interval. During post-treatment, frequency of skeletal anomalies decreased to less than 5% in all groups. Contributions No. 610, Environmental Research Laboratory, Gulf Breeze, Florida 32561 U.S.A. The information in this document has been funded wholly by the U.S. Environmental Protection Agency, and has been subjected to the Agency's peer and administrative review. Mention of commercial products or trade names does not constitute the Agency's endorsement or recommendation for use.     

Effect of salt nutrients on mannitol production by Lactobacillus intermedius NRRL B-3693

The effects of four salt nutrients (ammonium citrate, sodium phosphate, magnesium sulfate, and manganese sulfate) on the production of mannitol by Lactobacillus intermedius NRRL B-3693 in a simplified medium containing 300 g fructose, 5 g soy peptone, and 50 g corn steep liquor per liter in pH-controlled fermentation at 5.0 at 37°C were evaluated using a fractional factorial design. Only manganese sulfate was found to be essential for mannitol production. Added manganese sulfate concentration of 0.033 g/l was found to support maximum production. The bacterium produced 200.6±0.2 g mannitol, 61.9±0.1 g lactic acid, and 40.4±0.3 g acetic acid from 300 g fructose per liter in 67 h.Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

黄土高原半干旱区轮作休耕模式对土壤真菌的影响

通过田间试验,研究休耕（CK）、残膜覆盖、伏天深耕、施有机肥、秸秆还田和绿肥还田对土壤微生物量碳氮、酶活性及真菌群落的影响。结果表明,除过氧化氢酶外,不同处理对土壤微生物量碳氮、脲酶、碱性磷酸酶、脱氢酶、pH及有机质均有显著影响。从门水平上看,土壤真菌群落主要由子囊菌门、担子菌门和被孢霉门构成。其中伏天深耕、玉米秸秆粉碎还田+施牛羊粪+深翻耕后连续休耕3年处理的子囊菌相对丰度分别为43.23%和69.38%,显著高于CK （33.71%）;从纲水平上看,座囊菌纲、粪壳菌纲、伞菌纲和被孢霉纲为优势菌纲,其中玉米秸秆粉碎还田+施牛羊粪+深翻耕后连续休耕3年处理以座囊菌纲为主（60.69%）,其余处理以粪壳菌纲为主（4.11%-24.79%）;真菌多样性指数施牛羊粪+深翻耕+连续3年种植豌豆（拌根瘤菌粉8.5 g/kg种子）并在盛花期翻压还田、玉米秸秆粉碎还田+施牛羊粪+深翻耕后连续休耕3年、玉米秸秆粉碎还田+施牛羊粪+深翻耕+连续3年种植箭筈豌豆并在盛花期翻压还田处理显著低于CK和其他处理,丰富度指数玉米秸秆粉碎还田+施牛羊粪+深翻耕+连续3年种植毛苕子并在盛花期翻压还田处理显著高于CK和其他处理;真菌营养类型玉米秸秆粉碎还田+施牛羊粪+深翻耕后连续休耕3年处理以腐生营养型为主（62.9%）,其他处理以病理营养型和腐生营养型为主。冗余分析和Monte Carlo置换检验结果显示,土壤微生物量碳、微生物量氮、pH和有机质含量对土壤真菌群落结构影响显著（P<0.05）。与休耕（CK）、残膜覆盖、伏天深耕相比,施有机肥、秸秆还田、绿肥还田结合深耕均降低了土壤中病理营养型真菌的相对丰度,利于保持农田土壤生态系统健康。     

深松和秸秆还田对甘肃引黄灌区土壤物理性状和玉米生产的影响

通过在甘肃引黄灌区灰钙土2015—2017年的田间试验,研究深松35 cm秸秆还田、深松35 cm秸秆不还田与传统旋耕秸秆不还田对土壤紧实度、容重、入渗率和0～100 cm土层土壤水分、玉米产量、养分吸收量的影响.结果表明: 与深松35 cm秸秆不还田及旋耕秸秆不还田相比,深松35 cm秸秆还田使0～40 cm土层土壤紧实度和容重降低最明显,2017年收获后紧实度与容重较2015年试验前分别下降42.6%、7.0%,且2016和2017年播种前与收获后0～40 cm土层紧实度和容重的变幅最小,紧实度变异系数平均为6.1%,容重为3.2%,土壤入渗率较旋耕秸秆不还田提高33.6%;深松35 cm秸秆还田可显著提高春秋两季0～100 cm土层剖面含水量,降低剖面水分变异,0～100 cm土层土壤贮水量较旋耕秸秆不还田春季增加15.5%,秋季增加5.6%,水分利用效率提高32.4%;此外,深松35 cm秸秆还田能促进玉米生产,较旋耕秸秆不还田的经济产量两年平均分别增产25.6%,生物产量提升33.3%,玉米氮、磷、钾养分吸收量分别提高49.6%、51.5%和37.6%.综上,深松35 cm秸秆还田能改善物理土壤特性,稳定耕层物理性状,提高0～100 cm土层剖面水分含量及春秋两季土壤平均贮水量,降低水分变异,是促进玉米水肥高效利用,实现高产的最优措施,为甘肃引黄灌区耕层构建技术的深入研究提供理论依据.     

不同耕作方式对茶园土壤物理性状及茶叶产量的影响

研究了免耕、旋耕和深松3种耕作方式对茶园土壤紧实度、土壤含水率、土壤容重、茶叶产量构成因素及茶叶产量的影响.结果表明: 3种耕作方式对土壤容重和土壤紧实度的影响效果为深松>旋耕>免耕.旋耕和深松能够打破粘盘层,降低深层土壤紧实度.0～30 cm耕层深松土壤容重较免耕下降16.4%,土壤紧实度下降13.4%～27.5%;深松可以显著增加土壤的储水空间,进而增强土壤持水能力,扩大土壤水库容,深松15～30 cm层含水量与免耕相比增加7.7%.不同耕作方式对土壤孔隙度影响不大.旋耕和深松方式下土壤比表面积增加,土壤气体和液体的比例均明显升高.茶叶的光合速率和蒸腾速率的日变化曲线均为“双峰”型,气孔因素是导致“午休”的主要原因.在深松方式下,茶树叶片蒸腾速率降低,芽叶密度增加,百芽干质量和水分利用效率升高,茶叶产量分别比免耕和旋耕增加17.6%和6.8%.深松是皖东地区茶园较为适宜的耕作方式.     

Advanced backcross QTL analysis of a hard winter wheat × synthetic wheat population

Advanced backcross quantitative trait locus (AB-QTL) analysis was used to identify QTLs for yield and yield components in a backcross population developed from a cross between hard red winter wheat (Triticum aestivum L.) variety Karl 92 and the synthetic wheat line TA 4152-4. Phenotypic data were collected for agronomic traits including heading date, plant height, kernels per spike, kernel weight, tiller number, biomass, harvest index, test weight, grain yield, protein content, and kernel hardness on 190 BC₂F_2:4 lines grown in three replications in two Kansas environments. Severity of wheat soilborne mosaic virus (WSBMV) reaction was evaluated at one location. The population was genotyped using 151 microsatellite markers. Of the ten putative QTLs identified, seven were located on homoeologous group 2 and group 3 chromosomes. The favorable allele was contributed by cultivated parent Karl 92 at seven QTLs including a major one for WSBMV resistance, and by the synthetic parent at three QTLs: for grain hardness, kernels per spike, and tiller number. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Conversion of agricultural feedstock and coproducts into poly(hydroxyalkanoates)

Aside from their importance to the survival and general welfare of mankind, agriculture and its related industries produce large quantities of feedstocks and coproducts that can be used as inexpensive substrates for fermentative processes. Successful adoption of these materials into commercial processes could further the realization of a biorefinery industry based on agriculturally derived feedstocks. One potential concept is the production of poly(hydroxyalkanoate) (PHA) polymers, a family of microbial biopolyesters with a myriad of possible monomeric compositions and performance properties. The economics for the fermentative production of PHA could benefit from the use of low-cost agricultural feedstocks and coproducts. This mini-review provides a brief survey of research performed in this area, with specific emphasis on studies describing the utilization of intact triacylglycerols (vegetable oils and animal fats), dairy whey, molasses, and meat-and-bone meal as substrates in the microbial synthesis of PHA polymers.Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.     

Insertion of a heterologous gene construct into a non-functional ORF of the Streptococcus thermophilus chromosome

An integrative vector was constructed for inserting heterologous genes within a non-functional open reading frame (ORF) on the chromosome of Streptococcus thermophilus. The vector, pINTRS, contained a temperature sensitive origin of replication and an erythromycin resistance gene for initial selection in S. thermophilus. The region of the vector containing unique cloning sites, for insertion of recombinant genes, was flanked by homologous DNA sequences corresponding to a pseudogene in S. thermophilus to facilitate chromosomal integration. The gene encoding green fluorescent protein, regulated by a plasmid borne hsp promoter of S. thermophilus, was cloned into pINTRS to demonstrate proper functioning of the vector. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.