scholarly journals Sorption and mobility of thiabendazole in a Brazilian Oxisol

2020 ◽  
Vol 42 ◽  
pp. e44
Author(s):  
Bianca Veloso Goulart ◽  
Wallace Nikolas dos Santos Nascimento ◽  
Ana Carolina Pinto ◽  
Patrícia Maralyne Lopes Lisboa Fagundes ◽  
Larissa Silva Maciel ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Adsorption Capacity ◽  
Clay Content ◽  
Soil Columns ◽  
Adsorption And Desorption ◽  
Adsorption Capacities ◽  
Study Results ◽  
Minas Gerais State ◽  
Ph Conditions

Thiabendazole is a benzimidazole class drug that is widely used due to its vermifugal and fungicidal properties. The present study investigates the behaviour of TBZ in the A and B horizons of a Red-Yellow Latosol typical of southern Minas Gerais State, Brazil. Adsorption and desorption assays were performed under different pH conditions (3.0, 4.2-5.1, and 8.5) and a leaching study was conducted using soil columns. The results demonstrated that the behaviour of TBZ in the soil was influenced by the pH, soil organic matter and clay content. The Freundlich constants  indicated that the adsorption capacities for horizons A and B were high (50-149 mg1-1/n.L1/n.kg-1) and low (0-24 mg1-1/n.L1/n.kg-1), respectively. The leaching study results indicated that for both horizons, TBZ presented higher sorption in the initial fractions of the column (0-2 cm), and that the B horizon had a lower adsorption capacity, compared to the A horizon.

scholarly journals Twenty-Five Years of Radiocarbon Dating Soils: Paradigm of Erring and Learning

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 541-549 ◽  
Author(s):  
H. W. Scharpenseel ◽  
Peter Becker-Heidmann
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Formation ◽  
Clay Content ◽  
Solvent System ◽  
Total Carbon ◽  
Earthworm Casts ◽  
Initiation Point ◽  
Organic Matter Fractions ◽  
Soil Dating

Soil organic matter sequesters close to three times the carbon existing totally in the living biomass and nearly the same for the total carbon in the atmosphere. Models, such as Jenkinson's or Parton's Century model, help to define soil organic matter fractions of different functions, based on residence time/14C age. Rejuvenation of soil carbon was felt to be the principal impediment to absolute soil dating, in addition to the ambiguity of the initiation point of soil formation and soil age. Recent studies, for example, of Becker-Heidmann (1989), indicate that a soil 14C age of >1000 yr cannot have >0.1% rejuvenation in the total soil organic matter compartments/fractions to be possible and sustainable. Always problematic in earlier observations were age vs. depth increases, in 14C profile curves showing an inflection of reduced age in the deepest samples, i.e., from the rim of the organic matter containing epipedon. We attribute this phenomenon, in mollic horizons, to earthworm casts in the terminal part of the escape tube. Becker-Heidmann (1989) has shown, in thin layer soil profile dating, a highly significant correlation between the highest 14C ages and the highest clay content. Thus, optimization of soil dating is, to a lesser degree, related to the applied extracting solvent system than to soil texture fractions. Such observations allow us to mitigate error ranges inherent in dating dynamic soil systems.

scholarly journals Relationship of soil properties to fractionation, bioavailability and mobility of lead and zinc in soil

2008 ◽  
Vol 53 (No. 5) ◽  
pp. 225-238 ◽  
Author(s):  
N. Finžgar ◽  
P. Tlustoš ◽  
D. Leštan
Keyword(s):  
Organic Matter ◽  
Regression Analysis ◽  
Soil Organic Matter ◽  
Soil Properties ◽  
Multiple Regression ◽  
Contaminated Soils ◽  
Organic Matter Content ◽  
Clay Content ◽  
Exchange Capacity ◽  
Matter Content

Sequential extractions, metal uptake by <i>Taraxacum officinale</i>, Ruby&rsquo;s physiologically based extraction test (PBET) and toxicity characteristic leaching procedure (TCLP), were used to assess the risk of Pb and Zn in contaminated soils, and to determine relationships among soil characteristics, heavy metals soil fractionation, bioavailability and leachability. Regression analysis using linear and 2nd order polynomial models indicated relationships between Pb and Zn contamination and soil properties, although of small significance (<i>P</i> < 0.05). Statistically highly significant correlations (<i>P</i> < 0.001) were obtained using multiple regression analysis. A correlation between soil cation exchange capacity (CEC) and soil organic matter and clay content was expected. The proportion of Pb in the PBET intestinal phase correlated with total soil Pb and Pb bound to soil oxides and the organic matter fraction. The leachable Pb, extracted with TCLP, correlated with the Pb bound to carbonates and soil organic matter content (<i>R</i><sup>2</sup> = 69%). No highly significant correlations (<i>P</i> < 0.001) for Zn with soil properties or Zn fractionation were obtained using multiple regression.

Spatial organization of soil microaggregates

2020 ◽  
Author(s):  
Eva Lehndorff ◽  
Nele Meyer ◽  
Andrey Radionov ◽  
Lutz Plümmer ◽  
Peter Rottmann ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Spatial Organization ◽  
Inorganic Compounds ◽  
Spatial Relationship ◽  
Clay Content ◽  
Spatial Arrangement ◽  
C Sequestration ◽  
Spatial Correlations ◽  
Soil Minerals

&lt;p&gt;The physical arrangement of soil compounds in microaggregates is important in many ways, e.g. by controlling soil stability and C sequestration. However, little is known about the spatial arrangement of organic and inorganic compounds in soil microaggregates, due to the lack of in-situ analyses in undisturbed material. Here we hypothesize that microaggregates are spatially organized, resulting in deterministic, predictable spatial patterns of different organic matter and mineral phases and that this organization depends on the abundance of specific phases such as on clay mineral content. We separated the water stable, occluded large and small microaggregate fractions from Ap horizons of a sequence of sandy to loamy Luvisols (19 to 35% clay, Scheyern, Germany) and subjected in total 60 individual aggregates to elemental mapping by electron probe micro analysis (EPMA), which recorded C, N, P, Al, Fe, Ca, K, Cl, and Si contents at &amp;#181;m scale resolution. Spatial arrangements of soil organic matter and soil minerals were extracted using cluster analyses. We found a pronounced heterogeneity in aggregate structure and composition, which was not reproducible and largely independent from clay content in soil. However, neighborhood analyses revealed close spatial correlations between organic matter debris (C:N app. 100:10) and microbial organic matter (C:N app. 10:1) indicating a spatial relationship between source and consumer. There was no systematic relationship between soil minerals and organic matter, suggesting that well-established macroscale correlations between contents of pedogenic oxides and clay minerals with soil organic matter storage do not apply to soil microaggregates.&lt;/p&gt;

SOIL ORGANIC MATTER, MOISTURE, AND TEMPERATURE: EFFECT ON WILD OATS CONTROL WITH TRIFLURALIN

1979 ◽  
Vol 59 (3) ◽  
pp. 763-768 ◽  
Author(s):  
J. R. MOYER
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Soil Organic Matter ◽  
Soil Moisture Content ◽  
Clay Content ◽  
High Moisture ◽  
Dose Rates ◽  
Wild Oats ◽  
Dose Recommendations ◽  
Dose Levels

The effect of soil organic matter (OM), clay content, temperature, and soil moisture on dose levels of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) required for 90% control of wild oats (Avena fatua L.) was assessed in growth chamber experiments. In the first experiment, where soil moisture was constant, variation in soil OM accounted for 94% of the variability in trifluralin dose rates required for 90% reduction in fresh weight of wild oats (GR90) whereas clay content and temperature had no significant effect. In a second experiment, where temperature was constant, required dose rates were slightly higher at low and high moisture levels than at intermediate levels. Variation in OM explained 80% of the variability in GR90 while the inclusion of moisture and (moisture)2 terms in the multiple regression analysis explained an additional 7% of the variability. The results indicate that trifluralin efficacy was primarily related to OM content and that current recommendations for trifluralin could be improved if based on this parameter. An even more accurate trifluralin dose could be predicted from OM content and soil moisture content but the improvement in efficacy would be slight. Soil OM content determined the amount of trifluralin, dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine), and fluchloralin [N(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)-aniline] adsorbed to soil. This suggests that dose recommendations and efficacy of dinitramine and fluchloralin could be predicted from OM content.

Dependence of soil respiration on soil moisture, clay content, soil organic matter, and CO2 uptake in dry grasslands

2011 ◽  
Vol 43 (5) ◽  
pp. 1006-1013 ◽  
Author(s):  
J. Balogh ◽  
K. Pintér ◽  
Sz. Fóti ◽  
D. Cserhalmi ◽  
M. Papp ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Soil Organic Matter ◽  
Soil Respiration ◽  
Clay Content ◽  
Co2 Uptake ◽  
Dry Grasslands

scholarly journals Adsorption and Desorption Behavior of Herbicide Mefenpyr-diethyl in the Agricultural Soils of Morocco

2018 ◽  
Vol 7 (5) ◽  
pp. 386-395 ◽  
Author(s):  
Abdellah El Boukili ◽  
Nidae Loudiyi ◽  
Ahmed El Bazaoui ◽  
Abderrahim El Hourch ◽  
M'Hamed Taibi ◽  
...  
Keyword(s):  
Organic Matter ◽  
Adsorption Capacity ◽  
Agricultural Soils ◽  
Organic Matter Content ◽  
Matter Content ◽  
Isotherm Models ◽  
Desorption Process ◽  
Adsorption And Desorption ◽  
Total Percentage ◽  
Adsorption Isotherm Models

The present study was conducted in order to investigate the adsorption and desorption behavior of Mefenpyr-diethyl (MFD) using the batch equilibration technique in four soils, with different ranges of organic matter content, from different regions of Morocco orders of Benimellal (Soil 1), Settat (Soil 2), Sidi Bettach (Soil 3) and EL Hajeb (Soil 4). The adsorption isotherm models Langmuir, linear and Freundlich were used to compare the adsorption capacity of the soils. The results indicated that the Freundlich equation provided the best fit for all adsorption data. The values of KF and Kd ranged from 4.45 to 15.9 and 4.30 to 18.30 L.kg-1 , respectively. The calculated total percentage of desorption values from the Soil 1, Soil 2, Soil 3 and Soil 4 after the four desorption process were 59 %; 55,6 %; 37,5 % and 52,5%, respectively. Highest adsorption and desorption were observed in soil 1, and the lowest was in soil 3. According to the adsorption and desorption results, organic matter and clay seemed to be the most important factors influencing the adsorption capacity of MFD.

scholarly journals Adsorption Characteristics of Oxytetracycline by Different Fractions of the Organic Matter from Humus Soil: Insight from Internal Structure and Composition

2020 ◽  
Vol 17 (3) ◽  
pp. 914
Author(s):  
Mengya Luo ◽  
Shengke Yang ◽  
Siqi Shen ◽  
Yu Li
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Adsorption Capacity ◽  
Internal Structure ◽  
Batch Experiments ◽  
N2 Adsorption ◽  
Sem Images ◽  
Organic Fractions ◽  
Adsorption Desorption ◽  
Humus Soil

For minimizing the transport of antibiotics to groundwater, the migration of antibiotics in soils should be investigated. Soil organic matter can affect the migration of antibiotics. To date, the influence of aromatics and aliphatic content of organic matter on the adsorption of antibiotics has been controversial. To better understand the reaction mechanism of soil organic matter with antibiotics, this study investigated the adsorption of oxytetracycline (OTC) by humus soils (HOS) and their fractions. HOS were sequentially fractionated into four organic fractions, including the removal of dissolved organic matter (HRDOM), removal of minerals (HRM), removal of free fat (HRLF), and nonhydrolyzable organic carbon (HNHC). Moreover, batch experiments revealed that adsorption capacity was ordered by HNHC > HOS > HRDOM > HRLF > HRM. SEM images and N2 adsorption/desorption isotherms indicate that adsorption capacity is independent of the external structure. However, adsorption capacity is related to the internal structure and composition. Combination analysis with elemental composition and infrared spectroscopy showed that the adsorption capacity of HRM, HRLF, and HNHC had a good positive correlation with aromaticity, but a negative correlation with polarity and hydrophilicity. Additionally, the rule of binding affinity between OTC and functional groups with different properties was summarized as aromatic > polarity > hydrophilic.

scholarly journals Development of a composite soil degradation assessment index for cocoa agroecosystems in southwestern Nigeria

Solid Earth ◽  
2017 ◽  
Vol 8 (4) ◽  
pp. 827-843 ◽  
Author(s):  
Sunday Adenrele Adeniyi ◽  
Willem Petrus de Clercq ◽  
Adriaan van Niekerk
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Properties ◽  
Cation Exchange ◽  
Cation Exchange Capacity ◽  
Soil Degradation ◽  
Clay Content ◽  
Exchange Capacity ◽  
Southwestern Nigeria ◽  
Assessment Index

Abstract. Cocoa agroecosystems are a major land-use type in the tropical rainforest belt of West Africa, reportedly associated with several ecological changes, including soil degradation. This study aims to develop a composite soil degradation assessment index (CSDI) for determining the degradation level of cocoa soils under smallholder agroecosystems of southwestern Nigeria. Plots where natural forests have been converted to cocoa agroecosystems of ages 1–10, 11–40, and 41–80 years, respectively representing young cocoa plantations (YCPs), mature cocoa plantations (MCPs), and senescent cocoa plantations (SCPs), were identified to represent the biological cycle of the cocoa tree. Soil samples were collected at a depth of 0 to 20 cm in each plot and analysed in terms of their physical, chemical, and biological properties. Factor analysis of soil data revealed four major interacting soil degradation processes: decline in soil nutrients, loss of soil organic matter, increase in soil acidity, and the breakdown of soil textural characteristics over time. These processes were represented by eight soil properties (extractable zinc, silt, soil organic matter (SOM), cation exchange capacity (CEC), available phosphorus, total porosity, pH, and clay content). These soil properties were subjected to forward stepwise discriminant analysis (STEPDA), and the result showed that four soil properties (extractable zinc, cation exchange capacity, SOM, and clay content) are the most useful in separating the studied soils into YCP, MCP, and SCP. In this way, we have sufficiently eliminated redundancy in the final selection of soil degradation indicators. Based on these four soil parameters, a CSDI was developed and used to classify selected cocoa soils into three different classes of degradation. The results revealed that 65 % of the selected cocoa farms are moderately degraded, while 18 % have a high degradation status. The numerical value of the CSDI as an objective index of soil degradation under cocoa agroecosystems was statistically validated. The results of this study reveal that soil management should promote activities that help to increase organic matter and reduce Zn deficiency over the cocoa growth cycle. Finally, the newly developed CSDI can provide an early warning of soil degradation processes and help farmers and extension officers to implement rehabilitation practices on degraded cocoa soils.

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