scholarly journals Spatial variability of particle size fractions of an Oxisol cultivated with conilon coffee

Revista CERES ◽  
2012 ◽  
Vol 59 (6) ◽  
pp. 867-872 ◽  
Author(s):  
Julião Soares de Souza Lima ◽  
Rone Batista de Oliveira ◽  
Samuel de Assis Silva
Keyword(s):  
Particle Size ◽  
Spatial Variability ◽  
Clay Fraction ◽  
Soil Samples ◽  
Landscape Configuration ◽  
Sand Fraction ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Average Value ◽  
Significant Difference

Information on the spatial distribution of particle size fractions is essential for use planning and management of soils. The aim of this work to was to study the spatial variability of particle size fractions of a Typic Hapludox cultivated with conilon coffee. The soil samples were collected at depths of 0-0.20 and 0.20-0.40 m in the coffee canopy projection, totaling 109 georeferentiated points. At the depth of 0.2-0.4 m the clay fraction showed average value significantly higher, while the sand fraction showed was higher in the depth of 0-0.20 m. The silt showed no significant difference between the two depths. The particle size fractions showed medium and high spatial variability. The levels of total sand and clay have positive and negative correlation, respectively, with the altitude of the sampling points, indicating the influence of landscape configuration.

STUDIES ON THE DYNAMICS OF "RECENTLY" CLAY-FIXED NH4+ USING 15N

1980 ◽  
Vol 60 (1) ◽  
pp. 61-70 ◽  
Author(s):  
C. G. KOWALENKO ◽  
G. J. ROSS
Keyword(s):  
Particle Size ◽  
Clay Fraction ◽  
Extraction Methods ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Fine Clay ◽  
Tracer Methods ◽  
Field And Laboratory Conditions ◽  
The Relationship ◽  
Fast Release

The dynamics of fixation and release of NH4+ in soils were studied using tracer N under field and laboratory conditions. Field data showed that release of fixed NH4+ was relatively slow after an initial moderately fast release. Forty months of field weathering of Bainsville soil left 3.48 kg 15N/ha in the 75-cm profile of the 13.5 kg 15N/ha applied and most (76%) of this recovered 15N was fixed NH4+–N. The relative quantitative importance of recently fixed NH4+ in the various particle size fractions was not in the same order as the native fixed NH4+. The fine silt fraction (2–5 μm) fixed a larger amount (whole soil basis) than the fine clay fraction (< 0.2 μm). The coarse clay fraction (0.2–2 μm) fixed the most NH4+ added as well as being the fraction containing the most native fixed NH4+. Sand size fractions were shown to contain native fixed NH4+ and were capable of fixing a small amount of added NH4+. Measurements of recently fixed NH4+–N in various particle sizes covering four time intervals (up to 40 mo) of field weathering under fallow showed that the 0.2 to 2-μm fraction was quantitatively most important, the < 0.2-μm fraction most readily released recently fixed NH4+ and the 2 to 5-μm fraction was the most stable with respect to recently fixed NH4+. Plant growth affected the relative stability of the recently fixed NH4+ in the various particle size fractions. Laboratory studies of three Brookston soil samples revealed higher estimates of fixation of NH4+ by direct tracer methods than by indirect extraction methods. This discrepancy was assumed to have been caused by some exchange of added NH4+ with native fixed NH4+ and by some NH4+ being fixed on other sites. The relationship between mineralogical and related analyses to fixation of NH4+ was discussed.

Distribution of Organic Matter in the Particle Size Fractions of Lateritic Soil (Plinthosol)

2012 ◽  
Vol 63 (4) ◽  
pp. 9-15 ◽  
Author(s):  
Zygmunt Brogowski ◽  
Wojciech Kwasowski
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Organic Compounds ◽  
Soil Profile ◽  
Clay Fraction ◽  
Basaltic Rock ◽  
Lateritic Soil ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Opposite Trend

Abstract The distribution of organic matter in the genetic horizons of lateritic soil within a 100-cm profile to the basaltic parent rock is almost except for horizon Ap. Assuming that the sum of organic matter in 100 cm of the soil profile is 100%, 25.7% of these compounds occur in horizon Ap, whereas in the remaining horizons this value varies within 18-19.2%. In all size fractions, except the clay fraction in diameter of <0.002 mm, the content of organic matter decreases to a certain depth, and increases again in the deepest horizon located directly on the solid basaltic rock. The clay fraction displays an opposite trend; the content of organic matter in them increases with depth. In the horizon at the depth of 60-80 cm, the clay fraction <0.002 mm accumulates half of the total sum of organic compounds of all the remaining fractions. Such distribution of organic matter in soil and among its particle size probably results from the character of the basaltic weathered debris, as well as climate and vegetation covering the studied area.

Assessment of sediment toxicity by metal speciation in different particle-size fractions of river sediment

2003 ◽  
Vol 47 (7-8) ◽  
pp. 233-241 ◽  
Author(s):  
J.G. Lin ◽  
S.Y. Chen ◽  
C.R. Su
Keyword(s):  
Heavy Metals ◽  
Particle Size ◽  
Aquatic Ecosystem ◽  
Metal Speciation ◽  
Sediment Toxicity ◽  
Clay Fraction ◽  
Potential Toxicity ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Mn Oxide

Mobility and toxicity of metals associated with sediments are generally affected by metal speciation and granular compositions. Due to the various speciation patterns of heavy metals in sediments, it is not reliable to assess the potential toxicity of heavy metals on the aquatic environment with the total concentrations of heavy metals in sediments. The purposes of this study were to investigate the distribution of metal speciation in different particle-size fractions of sediments collected from two rivers (the Ke-Ya River and Ell-Ren River) in Taiwan, and to assess their potential toxicity to the aquatic ecosystem. Metals in the exchangeable, carbonate-bound and Fe/Mn oxide-bound forms obtained by sequential extraction were considered to be mobile and related with anthropogenic pollution. The degree of metal pollution and potential toxicity of sediments were higher in the lower reaches of both rivers. The metal speciation in sediments had a bimodal distribution over particle-size fractions. Heavy metals were subject to accumulation in the silt/clay fraction (&lt;25μmm) and coarse sand (420-2,000μmm). By normalizing the sum of the exchangeable, carbonate-bound, and Fe/Mn oxide-bound metals, it suggested that the potential toxicity to the aquatic ecosystem was caused by the fine sediments as well as coarse sediments.

scholarly journals PROBABILITY OF PARTICLE-SIZE FRACTIONS OCCURRENCE IN DIFFERENT LANDFORMS

2018 ◽  
Vol 26 (4) ◽  
pp. 352-359
Author(s):  
Julião Soares de Souza Lima ◽  
Samuel Assis Silva ◽  
Daniel Pena Pereira ◽  
Marcelo Soares Altoé
Keyword(s):  
Particle Size ◽  
Clay Fraction ◽  
Spherical Model ◽  
Fine Sand ◽  
Coarse Sand ◽  
Indicator Kriging ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Probability Of Occurrence ◽  
Present Pattern

Knowing the variation of particle-size fractions, considering the relief forms, contributes for understanding the variation of other soil attributes. This work aimed to study the spatial distribution of the probability of particle-size fractions occurrence (clay, silt, very fine sand, fine sand, coarse sand, and total sand) in a clayey Oxisol with predominance of concave and convex curvatures. A sampling grid with 94 sampling points in 33x33m spacing at a depth of 0–0.20 m was built using a GPS. The spatial analysis was performed through indicator kriging. The spherical model was fit for all soil fractions, with ranges varying from 130 m to 280 m. In the region of convex curvature, the clay fraction presented the highest probability of occurrence (0.75 to 1.00), whereas in the concave region the coarse sand and total sand fractions presented the highest probability of occurrence. The very fine sand fraction and the silt did not present pattern of distribution in relation to the dominant curvatures of the relief.

scholarly journals Distribution of inorganic phosphorus in profiles and particle-size fractions across an established riparian buffer and adjacent cropped area at the Dian lake

2015 ◽  
Vol 7 (4) ◽  
pp. 3223-3244
Author(s):  
G. S. Zhang ◽  
J. C. Li
Keyword(s):  
Particle Size ◽  
Land Use Changes ◽  
Soil Layer ◽  
Clay Fraction ◽  
Inorganic Phosphorus ◽  
Riparian Buffer ◽  
Sand Particle ◽  
Particle Fraction ◽  
Size Fractions ◽  
Particle Size Fractions

Abstract. Riparian buffer can trap sediment and nutrients sourced from upper cropland and minimizing eutrophication risk of water quality. This study aimed to investigate the distributions of soil inorganic phosphorus (Pi) forms among profile and particle-size fractions in an established riparian buffer and adjacent cropped area at the Dian lake, Southwestern China. The Ca-bound fraction (62 %) was the major proportion of the Pi in the riparian soils. Buffer rehabilitation from cropped area had a limited impact on total phosphorus (TP) concentrations after 3 years, but has contributed to a change in Pi forms. At 0–20 cm soil layer, levels of the Olsen-P, nonoccluded, Ca-bound and total Pi were lower in the buffer than the cropped area; however, the Pi distribution between the cropped area and the buffer did not differ significantly as depth increased. The clay fraction corresponded to 57 % of TP and seemed to be both a sink for highly recalcitrant Pi and a source for labile Pi. The lower concentration of Pi forms in the silt and sand particle fraction in the surface soil was observed in the buffer area, which indicating that the Pi distribution in coarse particle fraction has sensitively responded to land-use changes.

scholarly journals Investigation of the dependence of the activity concentration of natural and artificial radionuclides on particle size in surface soil

2019 ◽  
Vol 24 ◽  
pp. 217
Author(s):  
I. K. Mitsios ◽  
D. J. Karangelos ◽  
M. J. Anagnostakis
Keyword(s):  
Particle Size ◽  
Activity Concentration ◽  
Surface Soil ◽  
Soil Samples ◽  
Size Fractionation ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Activity Concentrations ◽  
Particle Size Fractionation ◽  
Natural And Artificial Radionuclides

Surface soil radioactivity is being studied at NED-NTUA since almost thirty years. The last few years this research has expanded to the study of soil particle size fractionation of radionuclides. The purpose of the present work was to study the tendency of many radionuclides to accumulate in the smaller particle size fractions. To this end, soil samples were collected from an area in the NTUA Campus where 241Am contamination, due to a failed 241Am-tipped lightning rod, had been previously detected. The samples were separated into size fractions using a sieving machine and analyzed by gamma spectrometry to determine 210Pb, 241Am, 234Th, 228Ra, 228Th, 226Ra, 7Be, 137Cs and 40K. The activity concentrations of these nuclides were found to significantly differ among the size fractions examined.

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