bluuebunny/crossref_metadata_2025 huggingface dataset:
Extraction, identification, and quantification of volatile fatty acids (VFA) in rumen fluid samples using Reverse Phase High-Performance Liquid Chromatography with Diode Array Detector (RP HPLC-DAD)
Authors: Vargas Julián Andrés Castillo , Araújo Tiago Costa de , Mezzomo Rafael
Published: September 2020

In ruminant animals, volatile fatty acids (VFA) or short-chain fatty acids (SCFAs) are derived from the protein and carbohydrate fermentation by rumen microorganism. Hence, the VFA determination in rumen fluid allows the evaluation of the nutritional quality of a diet, as well as its potential impact on the chemical composition of ruminant milk and meat. Thus, we developed a protocol to extract, identify, and quantify acetic, propionic, butyric, valeric, and caproic acids in ruminal fluid samples using RP-HPLC-DAD. Despite literature findings had shown that the most suitable column for VFA chromatographic separation under HPLC-DAD is an ion-exchange column, our protocol showed that a C18 column also allows an efficient VFA separation of the aforementioned acid, except for butyric and iso-butyric acids. This condition may constitute a limitation of the Hypersil GOLD C18 column use for VFA determination. However, considering that the concentration of iso-butyric acid is significantly lower than that of butyric acid, a good estimation of butyric acid can be obtained.
Protocol for optical percutaneous needle biopsy of the liver
Authors: Dremin Viktor , Potapova Elena , Zherebtsov Evgeny , Kandurova Ksenia , Shupletsov Valery , Alekseyev Alexander , Mamoshin Andrian , Dunaev Andrey
Published: September 2020

Liver cancer remains one of the most widespread cancer types worldwide. The time spent on the diagnosis is one of crucial factors ensuring the effectiveness of treatment. As percutaneous needle biopsy remains the gold standard for liver diagnosis, it is necessary to develop new methods for improving this procedure. One of the most promising directions is multimodal optical biopsy. The proposed protocol describes the methodology of real-time in vivo optical measurements of liver lesions during the percutaneous needle biopsy of the liver. The multimodal approach combines the methods of fluorescence and diffuse reflectance spectroscopy and conventional histological analysis.
Anais III COPB - III Congresso de Odontologia da Paraíba - Edição Exclusive 2020
Authors: Santos Thayana Karla Guerra Lira dos , Macêdo Filho Robeci Alves , Silva Maria das Graças Barbosa da , Macedo João Lucas de Araújo , Santos Eduardo Augusto dos , Silva Rayssa Maria Pinheiro da , Santos Júnior Emiliano Marinho dos
Published: September 2020

EditorialO III COPB, maior encontro de Odontologia já realizado no Nordeste, ocorreu nos dias 6 e 7 de março de 2020, no Hotel Garden de Campina Grande em um grande teatro reunindo profissionais e acadêmicos estimulando a troca de conhecimentos, trazendo o que há de mais moderno e abordando os mais diversos temas. Com a presença de grandes palestrantes nacionais e internacionais, grandes nomes da Odontologia no Brasil e no mundo, contou com a participação de mais de 1,5 mil profissionais e estudantes de Odontologia.Comissão Organizadora - III COPB - Edição Exclusive 2020
Water Flux below the Root Zone vs. Drip‐Line Spacing in Drip‐Irrigated Corn
Authors: Darusman  , Khan Akhter H. , Stone Loyd R. , Lamm Freddie R.
Published: September 2020

Use of microirrigation (drip) is increasing, prompted by factors such as a greater ability to control losses of water and nutrients from the root zone. The cost of drip can be reduced by using wider drip‐line spacings. Our objective was to evaluate water flux below the root zone (1.5‐m soil depth) with a subsurface drip irrigation system having drip‐line spacings of 1.5, 2.3, and 3.1 m near Colby, KS. The soil is a deep silt loam that formed in loess. The crop was corn (Zea mays L.), planted in rows spaced 0.76 m apart. Water flux at the 1.5‐m soil depth was determined in five treatments (Trt.): 1.5‐m spacing, full irrigation; 2.3‐m spacing, 67% of full irrigation; 2.3‐m spacing, full irrigation; 3.1‐m spacing, 50% of full irrigation; and 3.1‐m spacing, full irrigation. With full irrigation, irrigation plus effective rain equaled calculated corn evapotranspiration (ET). Tensiometers were placed below the drip line and at increments of 0.4 m from the drip line at soil depths of 1.4 and 1.7 m. Water flux was calculated by using a hydraulic conductivity (K) vs. matric potential (ψm) relationship, ψm data from tensiometers within the corn plots, and Darcy's equation of water flow. In‐season water fluxes below the root zone (1.5 m) were 51, 118, and 124 mm at drip‐line spacings of 1.5, 2.3, and 3.1 m, respectively. In 1990, corn grain yield was not significantly affected by spacing. In 1991, with drier initial soil‐water conditions, corn yielded significantly less grain at spacings of 2.3 m (11.5 Mg ha‐1) and 3.1 m (10.7 Mg ha‐1) than at a drip‐line spacing of 1.5 m (13.1 Mg ha‐1). If spacing between drip lines is increased beyond 1.5 m in the silt loam soils of western Kansas, there would be an associated increase in internal drainage from the root zone and decrease in corn yields.
Color Identification of Iron Oxides and Hydroxysulfates
Authors: Scheinost A.C. , Schwertmann U.
Published: September 2020

Colors are widely used to describe soil profiles but seldom to identify minerals. This study was conducted to determine whether color measurements with a colorimeter could be employed to identify Fe oxides and hydroxysulfates, either as monomineralic samples or in soils. We measured the color of 277 Fe oxide and hydroxysulfate mineral samples, as well as 309 soils and soil fractions. Discriminant analysis was employed to separate the minerals in three different color systems: CIE‐Yxy, CIE‐L*a*b*, and Munsell. Using the color of monomineralic samples, 100% of maghemites and jarosites could be correctly classified, 95% of goethites, 90% of feroxyhites, 84% of lepidocrocites, 83% of hematites, 56% of ferrihydrites, 50% of akagan e ´ ites, and 44% of schwertmannites. In soil samples, goethite (90% correct classifications) could be reliably distinguished from hematite–goethite mixtures (82% correct classifications), and from lepidocrocite–goethite mixtures (89%). The identification of ferrihydrites, akagan e ´ ites, and schwertmannites largely failed because of similar average colors and because of high color variability. Because the color variability is a mineral‐intrinsic property rather than produced by errors of measurement, color is in principle unsuited for identifying ferrihydrites, akagan e ´ ites, and schwertmannites. However, color may be used to identify goethite, hematite, lepidocrocite, jarosite, maghemite, and feroxyhite with a relatively high reliability. The choice of color system is not crucial for this type of analysis.
Bioactivation of Poorly Soluble Phosphate Rocks with a Phosphorus‐Solubilizing Fungus
Authors: Goenadi Didiek H. , Siswanto  , Sugiarto Yudho
Published: September 2020

Many studies have demonstrated ineffectiveness of finely ground phosphate rock (PR) use due to the low solubility of its P contents. This study was conducted to develop a simple, effective, and environmentally sound process to improve P availability of PR to crops by using a phosphate‐solubilizing fungus (PSF),Aspergillus nigerBCC F.194, isolated from tropical acid soils. The optimum incubation period and the optimum level of PR were determined. The P‐solubilizing effect of the supernatant of 9‐d‐old liquid culture supernatant (LCS) of the fungus was also determined by reacting it at various concentrations with Morrocan phosphate rock (MPR). The inoculation of the growth media with the PSFA. nigerresulted in the highest P solubility of the rock after 9 d of culturing at 2.5 g L−1MPR. Up to a certain degree, direct inoculation of fungal biomass and its LCS onto MPR caused a remarkable increase in 2% citric acid–soluble P, but not in water‐soluble P content. The possibilities of using the LCS instead of H2SO4in superphosphate (SP) production and using both with lower H3PO4concentrations were investigated with MPR as raw materials. Replacement of H2SO4by the LCS in the SP production process yielded a comparable 2% citric acid–soluble P content. Combining the LCS and H2SO4reduced the consumption of H3PO4that occurs in standard SP production. This LCS technique provides a practical means for an effective bioactivation of PR intended for both as a P fertilizer and a raw material of the SP.
Optimal Phosphorus Management Strategies for Wheat–Rice Cropping on a Loamy Sand
Authors: Yadvinder-Singh  , Dobermann A. , Bijay-Singh  , Bronson K. F. , Khind C. S.
Published: September 2020

Knowledge about optimal P rates for wheat (Triticum aestivum L.)–rice (Oryza sativa L.) cropping is insufficient because of nutrient availability differences between aerobic and anaerobic soil. We assessed P management strategies in a wheat–rice rotation on a Typic Ustochrept at Ludhiana, India. Seven P fertilizer treatments applied to wheat and rice, respectively, (P0‐0, P0‐26, P13‐13, P26‐0, P26‐13, P39‐0, and P26‐26; treatment abbreviations used include P applied to wheat followed by P applied to rice, both in kg ha−1) were compared from 1990 to 1997. Grain yield and seasonal P accumulation by wheat were highest for higher P rates and remained stable in treatments with P applied to wheat. Phosphorus application to rice increased P accumulation by rice, but did not consistently increase rice yields because flooding decreased soil P sorption and increased P diffusion resulting in higher P supply to rice relative to wheat. Indigenous soil P supply measured in wheat was 5.8 to 8.0 kg P ha−1, as compared with 14.9 to 18.1 kg P ha−1 in rice. Phosphorus adsorbed by ion‐exchange resin capsules placed in situ was five times greater under rice than under wheat. Applying only 26 kg P ha−1 to wheat and no P to rice was not economical and led to a negative P balance and a decline in soil P. Applying 32 kg P ha−1 to wheat and 15 kg P ha−1 to rice was optimal for achieving short‐term economic and long‐term agronomic goals when both grain and straw were removed from the field. These findings require further validation at other sites, at higher rice yield levels, and for different straw management.
Yield and Soil Nutrient Changes in a Long‐Term Rice‐Wheat Rotation in India
Authors: Bhandari A. L. , Ladha J. K. , Pathak H. , Padre A. T. , Dawe D. , Gupta R. K.
Published: September 2020

Major improvements in the productivity of rice (Oryza sativaL.) and wheat (Triticum aestivumL.) have occurred in South Asia since 1965–1966 when the Green Revolution began. However, after the 1980s, yield stagnated or declined. We analyzed grain yield trends, soil C, N, P, and K status, and P and K balances in a 14‐yr rice–wheat experiment conducted at Punjab, India with 11 treatments comprised of various combinations of inorganic and organic sources of nutrients. Recommended levels of N, P, and K were supplemented with N through farmyard manure (FYM), wheat chopped straw (WCS), or sesbania (Sesbania cannabinaLinn. & Merrill). Soil parameters were analyzed in archived soil samples collected periodically from 1988 to 1999. Rice yield declines ranged from 0.07 to 0.13 Mg ha−1yr−1dependent on treatment. Wheat yields declined by 0.04 Mg ha−1yr−1with applications of 75 and 100% N‐P‐K fertilizer but were maintained over the 14‐yr period in the other treatments. Total soil N and available P and K declined in all the treatments except with FYM, in which total N was maintained and available P increased. Total soil C was either maintained or increased with time. Nitrogen and K depletion may have collectively contributed to the yield decline. Stable wheat yields may have been because of continuing variety improvement, resulting in higher harvest index (HI). Results show that current fertilizer recommendations are inadequate for maintaining yields. This cropping system may not be sustainable without increased K input to maintain soil K above sufficiency levels.
Erosion Patterns on Cultivated and Reforested Hillslopes in Moscow Region, Russia
Authors: Olson K. R. , Gennadiyev A. N. , Jones R. L. , Chernyanskii S.
Published: September 2020

The severity of accelerated erosion is affected by tillage practices, slope gradient, shape, and length. Our hypothesis is that fly ash, the product of high temperature coal combustion, magnetic minerals, magnetic susceptibility, and organic C content of a soil can be used to estimate the extent of soil loss as a result of human activities. The objectives of the current study near Pushkino, Russia were: (i) to determine the extent and local variability of soil removal from a hillslope because of accelerated erosion using closely spaced duplicate transects, and (ii) to determine subsequent deposition of sediments on a lower landscape position using the presence, depth distribution, and concentration of fly ash, magnetic minerals, organic C, and magnetic susceptibility. The study was done by comparing the amount of fly ash contained in soil profiles at different landscape positions of a cultivated site with that at a reforested site planted to spruce [Picea abies(L.) Karst] trees ∼60 to 80 yr ago. Deposition of fly ash derived from distant railway traffic started in or about 1851 and increased in 1870 because of construction of a closer railway. Considering the whole transect, the cultivated site had 12% less fly ash in the upper 20‐cm soil layer as compared with the reforested site. The fly‐ash results indicated that only 2.4 cm or 12% of the upper soil layer has been removed from the hillslope because of accelerated erosion associated with the last 60 to 80 yr of cultivation. Deposition of sediment rich in fly ash on the lower and upper footslopes suggests accelerated erosion has occurred at the cultivated site.
Mid‐Infrared and Near‐Infrared Diffuse Reflectance Spectroscopy for Soil Carbon Measurement
Authors: McCarty G. W. , Reeves J. B. , Reeves V. B. , Follett R. F. , Kimble J. M.
Published: September 2020

The ability to inventory soil C on landscapes is limited by the ability to rapidly measure soil C. Diffuse reflectance spectroscopic analysis in the near‐infrared (NIR, 400–2500 nm) and mid‐infrared (MIR, 2500–25000 nm) regions provides means for measurement of soil C. To assess the utility of spectroscopy for soil C analysis, we compared the ability to obtain information from these spectral regions to quantify total, organic, and inorganic C in samples representing 14 soil series collected over a large region in the west central United States. The soils temperature regimes ranged from thermic to frigid and the soil moisture regimes from udic to aridic. The soils ranged considerably in organic (0.23–98 g C kg−1) and inorganic C content (0.0–65.4 g CO3‐C kg−1). These soil samples were analyzed with and without an acid treatment for removal of CO3 Both spectral regions contained substantial information on organic and inorganic C in soils studied and MIR analysis substantially outperformed NIR. The superior performance of the MIR region likely reflects higher quality of information for soil C in this region. The spectral signature of inorganic C was very strong relative to soil organic C. The presence of CO3 reduced ability to quantify organic C using MIR as indicated by improved ability to measure organic C in acidified soil samples. The ability of MIR spectroscopy to quantify C in diverse soils collected over a large geographic region indicated that regional calibrations are feasible.
Sorption and Desorption of Pesticides by Clay Minerals and Humic Acid‐Clay Complexes
Authors: Li Hui , Sheng Guangyao , Teppen Brian J. , Johnston Cliff T. , Boyd Stephen A.
Published: September 2020

In soils, organic matter and minerals are often associated such that it is unclear how the presence of the former component influences the sorptive properties of the latter one. In this study, sorption and desorption of the herbicides 4,6‐dinitro‐o‐cresol (C7H6N2O5) and dichlobenil (C7H3Cl2N) by Ca2+–, K+–smectites, and humic acid–smectite complexes, was investigated using batch‐equilibrations and x‐ray diffraction (XRD). Greater sorption of 4,6‐dinitro‐o‐cresol compared with dichlobenil was observed for both smectites and humic acid–smectite complexes. For both pesticides, K+ smectites were more effective sorbents than Ca2+ smectites, with the lower charge‐density clay (SWy‐2) displaying a greater sorption capacity than the higher charge‐density clay (SAz‐1). The presence of humic acid did not impact pesticide sorption by K+ clays, but could enhance or suppress pesticide sorption by Ca2+–clays. A composite model for estimating pesticide sorption, which assumes mineral and organic matter function individually as sorbent phases, predicted sorption within a factor of 0.8 to 1.5 times the measured values. Humic acid did not contribute to pesticide desorption hysteresis in K+–humic acid–clay complexes, but was a source of hysteresis in the corresponding Ca2+ complexes. The basal spacings of K‐SWy‐2 and humic acid‐modified K‐SWy‐2 increased gradually from approximately 10.4 to 12.2 Å with increasing 4,6‐dinitro‐o‐cresol loadings. Also, XRD patterns of humic acid‐modified and unmodified K‐SWy‐2 smectite clays were found identical. These results demonstrate the intercalation of 4,6‐dinitro‐o‐cresol and suggest that humic acids are restricted to the external surfaces of clay tactoids. Together, these results indicate that clay mineral fractions in soils, including those with organic coatings, may play an important role in the retention of certain pesticides.
The Role of Particulate Organic Matter in Phosphorus Cycling
Authors: Salas A. M. , Elliott E. T. , Westfall D. G. , Cole C. V. , Six J.
Published: September 2020

In tropical cropping systems, a better understanding of P transformations and short‐term P cycling during decomposition of incorporated residues is pertinent. The primary objectives of this study were (i) to assess P immobilization in decomposing residues of sorghum (Sorghum bicolor(L.) Moench.) and crotalaria (Crotalaria junceaL.), (ii) to establish the role of soil fungi in the process, and (iii) to determine the contribution of P immobilization in explaining differences in soil P availability from plant residues in two weathered soils (Ultisol and Alfisol). Phosphorus associated with particulate organic matter (POM‐P) was measured at different residue decomposition stages. Irradiated and nonirradiated residues were utilized to evaluate the origin of fungal colonization of particulate organic matter (POM). Results indicate a significant release of P from the residues at early stages of decomposition. An average of 93 and 76% of the initial POM‐P was released after 5 d of decomposition in the Ultisol and Alfisol, respectively; and no significant differences were found between the residue types. After this initial 5‐d period, significantly higher values of POM‐P were observed for sorghum (5.8 and 7.9 mg P kg−1) as compared with crotalaria (1.9 and 2.8 mg P kg−1) in the two soils, suggesting a higher P immobilization in decomposing sorghum residue. Phosphorus immobilization represented up to 30% of the P in the residues and it could account for observed differences in P availability in the amended soils. A correspondence between patterns of P accumulation and fungal colonization of POM suggested that soil fungi might be responsible for this P immobilization. Further research is required however, to identify the mechanisms regulating this fungal colonization and P immobilization of plant residues in tropical acid soils.
A Markov Chain‐Based Probability Vector Approach for Modeling Spatial Uncertainties of Soil Classes
Authors: Li Weidong , Zhang Chuanrong , Burt James E. , Zhu A-Xing
Published: September 2020

Due to our imperfect knowledge of soil distributions acquired from field surveys, spatial uncertainties inevitably arise in mapping soils at unobserved locations. Providing spatial uncertainty information along with survey maps is crucial for risk assessment and decision‐making. This paper introduces a novel probability vector approach for spatial uncertainty modeling of soil classes based on an existing two‐dimensional Markov chain model for conditional simulation. The objective is to find an accurate and efficient way to represent spatial uncertainties that arise in mapping soil classes. Joint conditional probability distribution (JCPD) represented by a set of occurrence probability vectors (PVs) of soil classes is directly calculated from conditional Markov transition probabilities, rather than the conventional approximate estimation from a limited number of simulated realizations. By visualizing the calculated PVs, information reflecting spatial uncertainty of soil distribution can be quickly assessed. We hypothesize that these directly calculated PVs are equivalent to the PVs estimated from an infinite number of realizations and thus realizations visualized from the calculated PVs represent the spatial variation of soil distribution. This hypothesis is supported by simulation results showing that: (i) with increasing the number of realizations generated by the Markov chain model from 10 to 100 and to 1000, PVs estimated from these realizations gradually approach the calculated PVs; (ii) similar to simulated realizations, realizations visualized from calculated PVs also can reflect the spatial patterns of soil classes and approximately reproduce the complex indicator variograms of soil classes of the original soil map.
Denitrification and Organic Carbon Availability in Riparian Wetland Soils and Subsurface Sediments
Authors: Hill Alan R. , Cardaci Mia
Published: September 2020

The influence of organic C quantity and quality on denitrification in riparian environments is poorly understood. We measured denitrification potential (DNP), organic matter, and several fractions of organic C in surface soils and subsurface sediments in a river riparian zone. Surface soils in conifer forest peat, mixed forest, and marsh sites had similar DNP, although mean organic matter ranged from 9.4% (marsh) to 19.6% (mixed forest) and 36.6% (peat). These soils also differed widely in organic C, water‐extractable C, and anaerobic mineralizable C. Mean DNP in peat at depths of 0.8 to 1.4 m was four times lower than in the surface peat. Mean organic matter and organic C were significantly greater in the deep peat than at the surface, whereas the other C fractions were similar. Mean organic matter content of buried channel sediments at depths of 2 to 3 m was 3.6%; however, mean DNP was 75 to 80 times lower than in the surface mixed forest and marsh soils. When the three surface soil sites were considered separately, anaerobic mineralizable C showed the highest correlation with DNP in the marsh soils (r= 0.87) and the conifer peat soil (r= 0.82). Water‐extractable C was also highly correlated with DNP in the marsh soils (r= 0.81). Correlations between DNP and either organic matter or the three C fractions were not significant in the deep peat, whereas the former channel sediments showed a significant relationship between DNP and both organic matter (r= 0.81) and water‐extractable C (r= 0.81). These results show that C quantity and quality influence DNP, but no single index was a good predictor for all soil types.
The Effects of Salinity on the Accuracy and Uncertainty of Water Content Measurement
Authors: Hook W. R. , Ferré T. P. A. , Livingston N. J.
Published: September 2020

We used an automatic network analyzer (ANA) operated in both time and frequency domain modes to investigate the measurement accuracy of metallic time domain reflectometry (TDR) probes operated in sands saturated with NaCl solutions of varying electrical conductivity (EC). We chose to use time domain transmission (TDT) measurements for this investigation to separate the effect of the bulk soil‐probe interaction from the effect of the large reflection typically found at the air–soil boundary for a TDR configuration. Pulse travel times and their variability increase with increasing pore‐water EC. The source of travel time variability arises from the extreme variability in pulse shape, thereby introducing a high degree of uncertainty to curve fitting routines used to determine travel times. Pulse shape distortion is due primarily to attenuation of high frequency components through conductive loss rather than by dispersion. There is generally good correspondence between pulse rise time and the average water content measurement error over a 0‐ to 40‐dS m−1 EC range. For rise times <6 ns, measurement errors are <0.1 m3 m−3 Given that rise times can be determined easily, we recommend that they be reported routinely as indicators of data quality. Because the variability of travel time measurements at a given EC is on the same order as the average difference between the travel time measured at that EC and that measured at zero salinity, pulse rise times cannot be used to correct for individual travel time measurements at high salinity. Similarly, knowledge of the EC of the medium may allow for identification of erroneous water content measurements, but does not allow for error correction.
Long‐Term Effects of Organic Inputs on Yield and Soil Fertility in the Rice–Wheat Rotation
Authors: Yadvinder-Singh  , Bijay-Singh  , Ladha J. K. , Khind C. S. , Gupta R. K. , Meelu O. P. , Pasuquin E.
Published: September 2020

The sustainability of the rice (Oryza sativaL.)–wheat (Triticum aestivumL.) rotation is important to Asia's food security. Intensive cropping with no return of crop residues and other organic inputs result in the loss of soil organic matter (SOM) and nutrient supply, and is assumed to be nonsustainable. We evaluated seven treatments comprised of various combinations of green manure (GM;Sesbania cannabinaL.); wheat straw (WS), farmyard manure (FYM), and urea on yields and yield trends; P and K balance; and soil fertility in a rice–wheat experiment (1988–2000) on a loamy sand in Punjab, India. Rice yields were comparable with GM + urea, WS + GM + urea, and urea alone, but yields were reduced when FYM was supplemented with N. Except during 1 yr, integrated use of FYM and GM produced equal or higher rice yields than other GM based treatments. Wheat straw incorporation reduced average rice yields by 7% compared with WS removal. After 5 yr of continuous application, FYM and WS were at par in increasing rice yields. Organic materials applied to rice had no residual effect on wheat yields except FYM, which increased yield by about 6% compared with urea alone. Rice yield declined by 0.02 to 0.13 Mg ha−1yr−1but wheat yields remained unchanged. Soil C increased with the application of WS and FYM. Potassium balance was highly negative. Although the causes of yield decline are unknown, inadequate K applications and changes in the climatic parameters are possible reasons.
Effects of Residue Decomposition on Productivity and Soil Fertility in Rice–Wheat Rotation
Authors: Yadvinder-Singh  , Bijay-Singh  , Ladha J. K. , Khind C. S. , Khera T. S. , Bueno C. S.
Published: September 2020

Rice (Oryza sativa L.)–wheat (Triticum aestivum L.) farmers in India burn or remove residues to facilitate seedbed preparation. Incorporation of residues before planting of the next crop generally decreases yields due to N immobilization. Since a window of about 40 d is available between rice harvest and wheat planting, the effect of time of incorporation on rice residue decomposition and N mineralization–immobilization was studied in 1992–1993. The mass loss of residue was 25% for a 10‐d, 35% for a 20‐d, and 51% for a 40‐d decomposition period before wheat planting. Nitrogen release from residue ranged from 6 to 9 kg ha−1 during the wheat season. The immobilization of urea N decreased when residue was allowed to decompose for 10‐d or longer. Based on these studies, a long‐term (1993–2000) experiment was conducted on a sandy loam soil to examine the effect of time of residue incorporation before sowing wheat when compared with burning or removal of residue on yields, N‐use efficiency, and soil fertility. The effect of wheat residue incorporation with green manure (GM, Sesbania cannabina L.) on subsequent rice yields was also determined. Residue incorporation for 10 to 40 d had no effect on wheat yields. Rice yields increased (0.18–0.39 Mg ha−1) when wheat residue was incorporated with GM. Starter N applied at residue incorporation did not influence wheat yields but decreased N recovery efficiency. Physiological efficiency was higher when rice straw was incorporated in wheat and when wheat straw plus GM were incorporated in rice than when rice straw was incorporated for 10 d or when the straw was burned. The long‐term application of rice residue increased C accumulation in soil.
Soil Carbon and Nitrogen Pools in Response to Tall Fescue Endophyte Infection, Fertilization, and Cultivar
Authors: Franzluebbers A. J. , Stuedemann J. A.
Published: September 2020

Tall fescue (Festuca arundinacea Schreb.) is an important cool‐season perennial forage used for grazing animals in the humid regions of the USA and throughout the world. The fungal endophyte Neotyphodium coenophialum Glenn, Bacon, & Hanlin naturally inhabits the majority of tall fescue stands producing a variety of alkaloids in leaf tissue that can cause animal health disorders on ingestion. We hypothesized that endophyte infection would modify the stock and activity of various soil C and N pools (total, particulate, microbial biomass, and mineralizable), but that fertilization (13.4–1.5–5.6 vs. 33.6–3.7–13.9 g N–P–K m−2 yr−1) and cultivar (‘Kentucky‐31’, K‐31; ‘AU‐Triumph’; and ‘Johnstone’) might alter these responses. Soil organic C and total N at a depth of 0 to 20 cm under K‐31 with high fertilization were greater with high (4197 g C m−2 and 266 g N m−2) than with low (3872 g C m−2 and 242 g N m−2) endophyte infection at the end of 20 yr. Under low fertilization, soil organic C and total N were not different between low and high endophyte infection. Differences in C and N pools among cultivars with low fertilization were as large as among K‐31 fertilization‐endophyte comparisons, but appeared to be related to factors other than endophyte infection frequency. Carbon and N contents of small macroaggregates (0.25–1.0 mm) were the only soil properties that were related (r = 0.70, P = 0.001) to endophyte infection frequency (range of 1–79%) across all treatments. Soil C and N pools can be modified by endophyte infection, but these results narrowed this phenomenon to (i) conditions of higher fertility and (ii) predominantly in small macroaggregates.
Precipitation of Dissolved Organic Matter by Aluminum Stabilizes Carbon in Acidic Forest Soils
Authors: Scheel T. , Dörfler C. , Kalbitz K.
Published: September 2020

Dissolved organic matter (DOM) is often neglected as a factor in the formation of stable soil organic matter (OM). Precipitation of DOM by dissolved Al could contribute substantially to C retention in acidic forest soils; however, no information is available on the stability of precipitated OM against microbial decay. We investigated the stability of Al–OM precipitates against microbial decay as related to (i) DOM composition, (ii) Al speciation, and (iii) the dissolved Al/C ratio. We produced Al–OM precipitates by adding AlCl3(molar Al/C ratios: 0.05–0.3) at pH values of 3.8 and 4.5 to DOM solutions derived from Oi and Oa horizons, from either beech (Fagus sylvatica L) or spruce [Picea abies(L.) Karst.] litter. Between 13 and 84% of the C was precipitated, depending on pH, Al/C ratio, and the type of DOM. Precipitates were found to be enriched in aromatic C and mostly depleted in N when compared with DOM. Only 0.5 to 7.7% of precipitated C was mineralized during 7 wk of incubation. Mineralization of Al–OM precipitates was up to 28 times less than that of the respective DOM solutions. The extent of mineralization of Al–OM precipitates formed at pH 3.8 was reduced by 50 to 75% when compared with those formed at pH 4.5. The stability of precipitates against microbial decay increased with larger aromatic C content and larger C/N ratios. Our study clearly demonstrated that a large fraction of DOM can be precipitated and is thereby substantially stabilized against microbial decay.
Soil Carbon Inventory by Wet Oxidation and Dry Combustion Methods: Effects of Land Use, Soil Texture Gradients, and Sampling Depth on the Linear Model of C‐Equivalent Correction Factor
Authors: Tivet Florent , Carlos de Moraes Sá João , Borszowskei Paulo Rogério , Letourmy Philippe , Briedis Clever , Ferreira Ademir Oliveira , Burkner dos Santos Thiago Massao Inagaki Josiane
Published: September 2020

Monitoring C content is essential for carrying out surveys and inventories on C storage in soils under different land uses (LUs). The objectives of the present study, which was conducted in five agro‐ecoregions in Brazil with contrasting climates, LU managements, soil texture gradients, and soil depths, were to: (i) develop a C‐equivalent correction factor (CF) between total organic carbon determined by dry combustion (TOCDC) and organic carbon by wet oxidation recorded by the Walkley–Black (OCWB) method, and (ii) assess the influence of LU, soil texture gradients, and sampling depth on a C‐equivalent CF based on a linear model adjusted for each experimental location. The results indicated an effect of LU at almost all sites, except for one subtropical location where clay content and sampling depth were the most important factors. Additionally, there were LU × clay and LU × sampling depth interactions on the C‐equivalent CF. The linear models computed to estimate the CF from this set of qualitative (LU) and quantitative variables (soil texture gradient and soil depth) differed among and within the agro‐ecoregions and LU managements. The C‐equivalent CF in subtropical sites ranged from 1.37 to 1.55, while for tropical sites ranged from 1.13 to 1.60. These models are site specific, and the results demonstrate the need to develop models calibrated for each site before extrapolating to other agro‐ecoregions to recalculate past soil C inventories and to evaluate temporal changes of SOC stocks.
Mechanism for developing an adaptive strategy in cognitive management of the it companies’ competitiveness
Authors: Pylypenko Andriy , Iermachenko Iegor
Published: September 2020

In the context of the sectoral policy of Ukraine’s economic development, experts identify the IT sector as one of the drivers of economic growth. The sector is characterized by higher than the global aver¬age economic growth rates, growth rates of tax deductions to local and state budgets, and growing growth rates in the share of exports in the overall structure of Ukraine’s exports. It was revealed that, along with positive trends, the development model of the IT sector in Ukraine remains extremely vulnerable to external “shocks”, since about 98% of orders are generated from the external market. In addition, outsourcing rather than product specialization is inherent in the IT sector of Ukraine. And in this case, the level of operational and financial efficiency, as shown by global statistics, is the lowest. This model of development of the IT sector is due to the low level of competitiveness of IT companies, a decrease in competitiveness in the global market, which necessitates the development of adequate mechanisms for managing the competitiveness of companies in the Ukrainian IT sector. The mechanism of forming an adaptive strategy in cognitive management of IT companies’ competitiveness is offered. This mechanism, in contrast to the existing ones, takes into account the contour of anticipation (warning), which allows determining the stability of competitive positions of companies in Ukraine’s IT sector and developing a proactive adaptive strategy aimed at maintaining a high level of competitiveness of IT companies in both local and global markets, increasing their business value. The blocks structure of the mechanism, the range of problems of each block and methods of their solution are determined.
Water geochemical markers allow estimation of the impact of climate change on the hydrological regime of an Alpine river (River Arve, France, Switzerland)
Authors: Nirel Pascale , Iorgulescu Ion , Filella Montserrat
Published: September 2020

The impact of climate change upon the hydrological regimes of streams has become an issue of major concern that requires adapted tools to detect and follow the scale of possible changes. In this study, we use a geochemical approach that exclusively relies on measurements of chemical concentrations in order to investigate the effect of climate change on the hydrological regime of the River Arve, a Franco-Swiss river running from the Alps to the River Rhône. Our method relies on the use of a dimensionless parameter, the ratio of uranium and barium concentrations in river waters. This marker has the advantage of not needing the measurement of river discharges. Its application to 25 years of data collected in the River Arve by Canton Geneva, Switzerland, leads to the conclusion that the glacio-nival signature is appearing earlier in the year and lasts for longer periods.
Future drought analysis using SPI and EDDI to consider climate change in South Korea
Authors: Won Jeongeun , Kim Sangdan
Published: September 2020

Prediction of drought is important for efficient water management, as the occurrence of droughts affects large areas over a long period. According to various climate change scenarios, it is reported that in the future, Korea's climate is likely to increase in temperature with increasing rainfall. This increase in temperature will have a big impact on evapotranspiration. The occurrence of drought begins mainly with two causes: lack of rainfall or an increase in evapotranspiration. Therefore, in this study, the impact of climate change on future droughts is revealed through the Standardized Precipitation Index (SPI) and the Evaporative Demand Drought Index (EDDI). These two drought indices with different characteristics are used to examine the trend of future drought, and a drought Severity-Duration-Frequency (SDF) curve was derived to quantitatively analyze the depth of future drought. Future droughts are projected by applying future climate data generated from various climate models.
Efficiency of horizontal subsurface flow constructed wetlands cultivated with grasses of different root systems
Authors: de Jesus Fernanda Lamede Ferreira , de Matos Antonio Teixeira , de Matos Mateus Pimentel
Published: September 2020

The objective of this study was to evaluate the influence of stoloniferous and fasciculated root systems, of Tifton 85 and vetiver grass respectively, on pollutant removal for primary treatment of sewage in horizontal subsurface flow constructed wetlands (HSSF-CWs). For this, three HSSF-CWs measuring 4 m × 1 m × 0.25 m, filling with gneiss gravel # 0 (D60 of 7.0 mm and 48.4% porosity) as substrate, were used. One unit was cultivated with Tifton 85 grass (HSSFT-CW), one with vetiver grass (HSSFV-CW) and one remained uncultivated (HSSFC-CW) as a control. Sewage was applied at a flow rate of 0.53–0.80 m3 d−1, corresponding to an organic loading rate of approximately 350 kg ha−1 d−1 (biochemical oxygen demand – BOD), which resulted in a hydraulic retention time of 0.6–0.9 day. The HSSFV-CW was more efficient than the HSSFC-CW in removing dissolved solids (measured as electrical conductivity) and reducing the total suspended solids (TSS), BOD5, turbidity and sodium concentration, while the HSSFT-CW was not superior in any way. The results indicate that cultivation of vetiver grass provided increased efficiency for removing pollutants from sewage when compared with Tifton 85-grass, in the HSSF-CW.
Ranking of hybrid wavelet-AI models by TOPSIS method for estimation of daily flow discharge
Authors: Farajpanah Hiwa , Lotfirad Morteza , Adib Arash , Esmaeili-Gisavandani Hassan , Kisi Özgur , Riyahi Mohammad Mehdi , Salehpoor Jaber
Published: September 2020

This research uses the multi-layer perceptron–artificial neural network (MLP-ANN), radial basis function–ANN (RBF-ANN), least square support vector machine (LSSVM), adaptive neuro-fuzzy inference system (ANFIS), M5 model tree (M5T), gene expression programming (GEP), genetic programming (GP) and Bayesian network (BN) with five types of mother wavelet functions (MWFs: coif4, db10, dmey, fk6 and sym7) and selects the best model by the TOPSIS method. The case study is the Navrood watershed in the north of Iran and the considered parameters are daily flow discharge, temperature and precipitation during 1991 to 2018. The derived results show that the best method is the hybrid of the M5T model with sym7 wavelet function. The MWFs were decomposed by discrete wavelet transform (DWT). The combination of AI models and MWFs improves the correlation coefficient of MLP, RBF, LSSVM, ANFIS, GP, GEP, M5T and BN by 8.05%, 4.6%, 8.14%, 8.14%, 22.97%, 7.5%, 5.75% and 10% respectively.
Geochemical characteristics of arsenic in groundwater during riverbank filtration: a case study of Liao River, Northeast China
Authors: Lu Shuai , Feng Xiaoyu , Su Xiaosi
Published: September 2020

Affected by groundwater exploitation in the riverside, the infiltration of river water to recharge groundwater will cause changes in the groundwater environment, which has an important impact on the geochemical behavior of arsenic in groundwater. In this study, the groundwater environment zones in the process of river water infiltration were divided, and the arsenic content in groundwater in the study area had a good correlation with the environment zones. In the weak oxidation environment zone and the weak reductive environment zone, as the distance from the riverbank increased, the arsenic content gradually increased. In the reduction environment zone, there was a decreasing trend in arsenic content in groundwater. The arsenic content in groundwater varied significantly with the seasons, and its dynamic characteristics were closely related to the water level. The arsenic content in groundwater decreased with the rise in groundwater level, and it responded obviously to the change of water level in the shallows. Overall, arsenic entered the groundwater from the solid phase through adsorption and desorption of exchangeable arsenic and exchangeable iron, and reductive dissolution of iron or manganese oxides bound iron in the medium during riverbank filtration.
Vermiproductivity, maturation and microbiological changes derived from the use of liquid anaerobic digestate during the vermicomposting of market waste
Authors: Crutchik Dafne , Rodríguez-Valdecantos Gustavo , Bustos Gabriela , Bravo Javier , González Bernardo , Pabón-Pereira Claudia
Published: September 2020

Recently, it has been suggested that the liquid fraction of anaerobic digestate, derived from the treatment of wastewater and solid wastes, could be used in vermicomposting as a solution to its disposal, and even for its valorization. Nevertheless, the literature does not provide enough information about its impact on the process of vermicomposting itself and on the final quality of the end-product. In this study, the effect of different doses of digestate in the vermicomposting process treating market waste is assessed measuring earthworm population dynamics, the bacterial community succession present in the vermibeds, as well as maturation and the end-quality of the vermicompost. Our results show that the addition of liquid digestate to the vermibeds increased the earthworms biomass, i.e. 71%, 94% and 168% in control, and vermibeds with 30% and 60% digestate, respectively. Further, the increase in the amount of N in the vermicompost decreased as the digestate addition increased, i.e. 75%, 8%, 3%. The maturity achieved was high in all treatments as shown by the C/N ratio, 7.98, 7.40 and 10.20, and the high seed germination rate, above 90%. Finally, the succession of the microbial community was not disturbed and compositional stabilization was reached after 92 days.
Los nuevos retornados de la migración maya yucateca en Estados Unidos
Authors: Cruz-Manjarrez Adriana , Baquedano-López Patricia
Published: September 2020

En este artículo investigamos la migración de retorno de niñas y niños de origen maya del estado de Yucatán que nacieron en Estados Unidos, que emigraron a México con sus familias cuando eran menores de edad entre las décadas de 1990 y 2010, y que en la actualidad (2018) son nuevos retornados en Estados Unidos. Con base en la perspectiva del retorno transnacional se analiza el retorno familiar a México, el retorno a Estados Unidos y la movilidad transnacional de esta generación. Se demuestra una gran movilidad familiar en el circuito migratorio península de Yucatán-California-Oregón; el regreso a Yucatán por causas familiares, sociales y económicas; el retorno a Estados Unidos por cuestiones económicas, educativas, y laborales; y, la integración de los nuevos retornados en las dinámicas familiares transnacionales que posibilitan la reproducción generacional y el sustento familiar en California y Yucatán.
Building an Associative Classification Data Model Based on the Apriori Method
Authors: Mulyukova K. V. , Kureichik V. M.
Published: September 2020

The purpose of the workis to explore the current problems and prospects of mining solution, big web data in real time, as well as the possibility of practical implementation of Web Mining technology for big web data on a practical example.Materials and methods.The study included a review of bibliographic sources on big data mining. We used Web Mining technology for associative analysis of large web data, as well as computer modeling of the practical task of transaction analysis using a general-purpose scripting language (PHP).Results.During the work, the specifics of the Data Mining technology were described, and a modern approach to the analysis of large web data –Web Mining was analyzed. A brief classification of tasks solved using Web Mining technology is given. The problem of data mining of large web data in a general-purpose scripting language (PHP) has been solved: the lack of libraries for data mining, the difficult normalization of data to the form necessary for associative analysis, interaction with the database management system. Also, an example showing an approach to the mining of large web data was implemented. Based on the understanding of Web Mining technology and the described difficulties of analyzing web data in the PHP language, methods for effectively solving the practical problem of analyzing web data based on transactions committed in a dynamic web application have been proposed. A module for associative analysis of customer transactions in the programming language PHP was developed. The module includes an intelligent data processing class. The structural scheme of the module and system architecture were developed. The constructed module allows us to solve the main part of the problem of associative analysis of large web data using Web Mining technology in order to solve the problem of identifying patterns in a large array of web data. Associative analysis of web data is much faster because of the combination of a general-purpose scripting language and an object-oriented approach.Conclusion.According to the results of the study, it can be argued that the current state of the technology for the analysis of large web data allows efficiently process data objects, identify patterns, obtain hidden data and receive complete statistical data in real time. The results can be used both for the purpose of the initial research of technologies for analyzing large web data, and as an addition to the content management system for the intelligent analysis of web data. The usage of the technology of associative analysis and the created universal handler class makes the created module flexible, while the possibility of manual integration makes this module universal. With manual integration, the database management system is not important. Algorithm methods work with selected data. This factor greatly simplifies the further development of program code.