scholarly journals Accumulation of physically protected organic carbon promoted biological activity in macro-aggregates of rice soils under long term rice cultivation

2016 ◽  
Author(s):  
Yalong Liu ◽  
Ping Wang ◽  
Lianqing Li ◽  
Kun Cheng ◽  
Jufeng Zheng ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Clay Fraction ◽  
Fine Sand ◽  
Coarse Sand ◽  
Rice Cultivation ◽  
Sand Fraction ◽  
Rice Soils ◽  
Size Fractions ◽  
Silt Fraction ◽  
Gene Abundance

Abstract. While carbon stabilization had been increasingly concerned as ecosystem properties, the link between carbon stabilization and soil biological activity had been yet poorly assessed in soil dynamics of carbon and aggregation. In this study, topsoil samples were collected from rice soils derived from salt marsh under different lengths of rice cultivation up to 700 years from a coastal area of China. Particle size fractions (PSF) of soil aggregates were separated using a low energy dispersion protocol. Carbon fractions in the PSFs were analyzed with either FTIR spectros copy or chemical fractionation. Soil microbial community of bacterial, fungal and archaeal were analyzed with molecular fingerprinting using specific gene primers. Soil respiration and carbon gain from maize straw amendment as well as enzyme activities were respectively measured, using lab incubation protocols. While the PSFs were dominated by fine sand (200–20 μm) and silt (20–2 μm) fractions, the mass proportion both of sand (2000–200 μm) and clay (< 2 μm) fraction increased with prolonged rice cultivation. Soil organic carbon was enriched mostly in coarse sand fraction (40–60 g/kg), followed by the clay fraction (20–25 g/kg), but depleted in the silt fraction (~ 10 g/kg). Contents of recalcitrant C pool were higher (33–40 % of total SOC) in both coarse sand and clay fractions than in fine sand and silt fractions (20–29 % of total SOC). However, the ratio of LOC/SOC showed a weak decreasing trend with decreasing size of the PSFs. Total soil DNA content in the size fractions followed a similar trend to that of SOC. Bacterial and archaeal gene abundance were concentrated in both sand and clay fractions but that of fungi in sand fraction only, but increased with prolonged rice cultivation in both sand and clay fractions. Change in community diversity with sizes of the PSFs was found of fungi and weakly of bacterial but not of archaeal. Soil respiration quotient (Respired CO2-C to SOC) was highest in silt fraction, follo wed by the fine sand fraction but lowest in sand and clay fractions in the rice soils cultivated over 100 years. Whereas, scaled by total DNA concentration, respiration was higher in silt fraction than in other fractions for these rice soils. For the size fractions other th an clay fraction, soil DNA concentration, archaeal gene abundance, normalized enzyme activity and carbon sequestration was seen increased but SOC- and DNA-content scaled soil respiration decreased, more or less with prolonged rice cultivation. Carbon chemical stability and respiration were in a similar between sand and clay fractions but correlations of total DNA contents and bacterial gene abundance as well as normalized enzyme activity to SOC and labile OC content were only observed in sand fraction only. Our findings suggested that carbon accumulation and stabilization was prevalent in both sand and clay fraction, only the coarse sand fraction was found responsible for bioactivity dynamics in the rice soils.

scholarly journals Microbial activity promoted with organic carbon accumulation in macroaggregates of paddy soils under long-term rice cultivation

2016 ◽  
Vol 13 (24) ◽  
pp. 6565-6586 ◽  
Author(s):  
Yalong Liu ◽  
Ping Wang ◽  
Yuanjun Ding ◽  
Haifei Lu ◽  
Lianqing Li ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Organic Carbon ◽  
Soil Respiration ◽  
Soil Aggregates ◽  
Fine Sand ◽  
Coarse Sand ◽  
Rice Cultivation ◽  
Rice Soils ◽  
Size Fractions ◽  
Gene Abundance

Abstract. While soil organic carbon (SOC) accumulation and stabilization has been increasingly the focus of ecosystem properties, how it could be linked to soil biological activity enhancement has been poorly assessed. In this study, topsoil samples were collected from a series of rice soils shifted from salt marshes for 0, 50, 100, 300 and 700 years from a coastal area of eastern China. Soil aggregates were fractioned into different sizes of coarse sand (200–2000 µm), fine sand (20–200 µm), silt (2–20 µm) and clay (< 2 µm), using separation with a low-energy dispersion protocol. Soil properties were determined to investigate niche specialization of different soil particle fractions in response to long-term rice cultivation, including recalcitrant and labile organic carbon, microbial diversity of bacterial, archaeal and fungal communities, soil respiration and enzyme activity. The results showed that the mass proportion both of coarse-sand (2000–200 µm) and clay (< 2 µm) fractions increased with prolonged rice cultivation, but the aggregate size fractions were dominated by fine-sand (200–20 µm) and silt (20–2 µm) fractions across the chronosequence. SOC was highly enriched in coarse-sand fractions (40–60 g kg−1) and moderately in clay fractions (20–25 g kg−1), but was depleted in silt fractions (∼ 10 g kg−1). The recalcitrant carbon pool was higher (33–40 % of SOC) in both coarse-sand and clay fractions than in fine-sand and silt fractions (20–29 % of SOC). However, the ratio of labile organic carbon (LOC) to SOC showed a weakly decreasing trend with decreasing size of aggregate fractions. Total soil DNA (deoxyribonucleic acid) content in the size fractions followed a similar trend to that of SOC. Despite the largely similar diversity between the fractions, 16S ribosomal gene abundance of bacteria and of archaeal were concentrated in both coarse-sand and clay fractions. Being the highest generally in coarse-sand fractions, 18S rRNA gene abundance of fungi decreased sharply but the diversity gently, with decreasing size of the aggregate fractions. The soil respiration quotient (ratio of respired CO2–C to SOC) was the highest in the silt fraction, followed by the fine-sand fraction, but the lowest in coarse-sand and clay fractions in the rice soils cultivated over 100 years, whereas the microbial metabolic quotient was lower in coarse-sand-sized fractions than in other fractions. Soil respiration was higher in the silt fraction than in other fractions for the rice soils. For the size fractions other than the clay fraction, enzyme activity was increased with prolonged rice cultivation, whereas soil respiration appeared to have a decreasing trend. Only in the coarse-sand fraction was both microbial gene abundance and enzyme activity well correlated to SOC and LOC content, although the chemical stability and respiratory of SOC were similar between coarse-sand and clay fractions. Thus, biological activity was generally promoted with LOC accumulation in the coarse-sand-sized macroaggregates of the rice soils, positively responding to prolonged rice cultivation management. The finding here provides a mechanistic understanding of soil organic carbon turnover and microbial community succession at fine scale of soil aggregates that have evolved along with anthropogenic activity of rice cultivation in the field.

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 MECHANICAL COMPOSITION OF THE SOILS FORMED ON LIMESTONES AND DOLOMITES IN THE REPUBLIC OF MACEDONIA

2017 ◽  
Vol 36 (1) ◽  
Author(s):  
Mile Markoski ◽  
Tatjana Mitkova ◽  
Kole Vasilevski ◽  
Zorica Tomić ◽  
Marjan Andreevski ◽  
...  
Keyword(s):  
Clay Fraction ◽  
Fine Sand ◽  
Coarse Sand ◽  
Parent Material ◽  
Sand Fraction ◽  
Terra Rossa ◽  
Physical Clay ◽  
Average Value ◽  
Fine Soil ◽  
The Republic

The paper presents results from the research of the influence of the parent material on the mechanical compo-sition of calcomelanosols, calcocambisols and terra rossa. The contents of the fine soil separates in the calcomelano-sols vary depending on the subtype. The physical sand fraction (coarse sand + fine sand) in the Amo horizon amounts 44.81% in the organomineral calcomelanosols, 40.13% in the organogenic and brownised calcomelanosols 36.52%. In the (B)rz horizon in the brownised calcomelanosols it amounts 32.64%. The content of clay + silt or physical clay in the Amo horizon amounts 55.19% in the organomineral calcomelanosols, 59.87% in the organogenic and the high-est content is in the brownised calcomelanosols 63.48%. The average value of this fraction in the horizon (B)rz in the brownised calcomelanosols amounts 67.36%. In the calcocambisols the average content of the fraction physical sand in the Amo horizon amounts 33.43%, and in the cambic horizon (B)rz 22.50%. In the terra rossa the fraction physical clay is represented with a greater percentage related to the physical sand fraction. In the Amo horizon, in the physical clay fraction, the clay fraction is predominant, average 43.08%, and 52.13% in the cambic horizon, and 24.90% in the Amo horizon and 19.37% in the (B)rz horizon for the silt fraction. From a research soils 36% of the soils are formed on massive limestone, 13% are formed on dolomitic limestone and bituminous marbles, 16% on plate (flat) limestone, 10% on dolomitic marbles and 12% on laminated (plate) dolomite and calcite.

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.

EVALUATION OF PROFILE DEVELOPMENT OF SOME SOLONETZIC SOILS OF SOUTH CENTRAL ALBERTA

1976 ◽  
Vol 56 (3) ◽  
pp. 149-158 ◽  
Author(s):  
A. BRUNELLE ◽  
S. PAWLUK ◽  
T. W. PETERS
Keyword(s):  
Particle Size ◽  
High Stability ◽  
Clay Fraction ◽  
Fine Sand ◽  
Size Reduction ◽  
Particle Size Reduction ◽  
Sand Fraction ◽  
South Central ◽  
Gain Reduction ◽  
Index Mineral

The process of solodization was studied with respect to its chemical, physical, and mineralogical aspect and with particular emphasis upon the clay fraction. The net gain or loss of clay occurring in each profile upon solodization was calculated with quartz in the fine sand fraction serving as index mineral. Preferential translocation of montmorillonite over illite was evident in all profiles. K2O content in the total clay fraction indicated that illitization had taken place. For each of three sampling sites, the more solodized members of the sequence of Solonetzic profiles showed a net gain of clay while the least solodized members showed either a deficit or a much smaller gain. Reduction in size of the coarse material (sand size) was evident in most profiles studied. In some profiles, particle size reduction of the sand fraction was accompanied by an increase in clay size quartz in the eluvial horizons which suggests that quartz distribution is to some degree also affected by solodization. Although the use of quartz as an index mineral may therefore not provide an absolute degree of accuracy in quantitative pedology, it was felt that its abundance and its high stability insured useful results.

scholarly journals Sediment Characterization and Monsoonal Impact on Beach Morphology at the Three Beaches along the Karachi Coast, Pakistan

2021 ◽  
Vol 12 (1) ◽  
pp. 8185
Author(s):  
Sumera Farooq ◽  
Nazia Arshad
Keyword(s):  
Monsoon Season ◽  
High Tide ◽  
Fine Sand ◽  
Coarse Sand ◽  
Sediment Characteristics ◽  
Sand Fraction ◽  
South West ◽  
South West Monsoon ◽  
Tide Level ◽  
West Monsoon

Sediment characteristics plays important role in the determination and functioning of coastal ecosystems. The present study is an attempt to evaluate the variability in sediment characteristics of the three beaches: Clifton, Sandspit and Buleji, at the Karachi coast. The samples were collected during pre-monsoon and south-west monsoon seasons to evaluate the seasonal differences. The sediments of the three sites showed variations in moisture content, organic matter and grain size. The highest mean moisture (27.17%) and organic contents (3.5 %) were recorded from the sediments of Clifton. The maximum fraction of sediments (> 80 %) consist of fine to very fine sand at all studied sites. The sediments of Clifton were high in very fine sand fraction and low in coarse sand fraction as compared to Sandspit and Buleji. The sediments of all the three studied sites are moderately sorted, negatively coarse-skewed and showed leptokurtic distribution. The studied beaches of Clifton, Sandspit and Buleji shows dissimilarity in sediment characteristics as indicated through Cluster and PCA analysis. The monsoonal influence on sediment characteristics was also observed at all the three studied beaches. The strong wave action during SW monsoon season results in the deposition of the coarser sediments at the high tide level thus increasing the steepness of the beaches.

scholarly journals The manifestation of VIS-NIRS spectroscopy data to predict and map soil texture in the Triffa plain (Morocco)

2020 ◽  
Vol 48 (1) ◽  
Author(s):  
Ayoub Lazaar ◽  
◽  
Kamal El Hammouti ◽  
Zakariae Naiji ◽  
Biswajeet Pradhan ◽  
...  
Keyword(s):  
Soil Texture ◽  
Near Infrared ◽  
Prediction Models ◽  
Root Zone ◽  
Clay Fraction ◽  
Coefficient Of Determination ◽  
Good Prediction ◽  
Sand Fraction ◽  
Silt Fraction ◽  
North East

The use of standard laboratory methods to estimate the soil texture is complicated, expensive, and time-consuming and needs considerable effort. The reflectance spectroscopy represents an alternative method for predicting a large range of soil physical properties and provides an inexpensive, rapid, and reproducible analytical method. This study aimed to assess the feasibility of Visible (VIS: 350-700 nm) and Near-Infrared and Short-Wave-Infrared (NIRS: 701-2500 nm) spectroscopy for predicting and mapping the clay, silt, and sand fractions of the soils of Triffa plain (north-east of Morocco). A total of 100 soil samples were collected from the non-root zone of soil (0-20 cm) and then analyzed for texture using the VIS-NIRS spectroscopy and the traditional laboratory method. The partial least squares regression (PLSR) technique was used to assess the ability of spectral data to predict soil texture. The results of prediction models showed excellent performance for the VIS-NIRS spectroscopy to predict the sand fraction with a coefficient of determination R2 = 0.93 and Root Mean Squares Error (RMSE) =3.72, good prediction for the silt fraction (R2=0.87; RMSE = 4.55), and acceptable prediction for the clay fraction (R2 = 0.53; RMSE = 3.72). Moreover, the range situated between 2150 and 2450 nm is the most significant for predicting the sand and silt fractions, while the spectral range between 2200 and 2440 nm is the optimal to predict the clay fraction. However, the maps of predicted and measured soil texture showed an excellent spatial similarity for the sand fraction, a certain difference in the variability of clay fraction, while the maps of silt fraction show a lower difference.

Characterization of the angle of repose of binary granular materials

2005 ◽  
Vol 42 (2) ◽  
pp. 683-692 ◽  
Author(s):  
Zamri Chik ◽  
Luis E Vallejo
Keyword(s):  
Granular Material ◽  
Average Diameter ◽  
Fine Sand ◽  
Friction Angle ◽  
Lateral Spreading ◽  
Coarse Sand ◽  
Angle Of Repose ◽  
Sand Fraction ◽  
Angle Of Internal Friction ◽  
Modes Of Failure

When a heap or pile of granular material accumulates at the toe of a failed slope, the pile rests at its angle of repose. The gradual build up of a heap of soil in the laboratory simulates the formation of the heap at the toe of a slope. In this study, the angle of repose developed by binary granular mixtures of coarse sand (1.16 mm in average diameter) and fine sand (0.10 mm in average diameter) was measured in the laboratory. The influence on the angle of repose by the roughness of the base on which the mixtures were placed was also investigated. When the mixtures were placed on a rough surface, the heap developed its angle of repose by two different modes of failure. When the mixtures were controlled by the coarse sand fraction, failure took place on a layer located at the free surface of the heap. When the fine sand fraction controlled the composition of the mixture, the heap developed its angle of repose after the material failed by lateral spreading. When the mixture was placed on a smooth surface, the heap developed its angle of repose by a single mode of failure, namely lateral spreading at the interface of the mixture and the smooth base. A theoretical analysis relating the angle of repose, the internal angle friction of the mixtures, and the interface basal friction angle is also presented.Key words: angle of repose, binary granular material, quartz sand, angle of internal friction, interface friction angle, Rankine earth pressure theory.

scholarly journals Total mercury distribution among soil aggregate size fractions in a temperate forest podzol

2018 ◽  
Vol 8 ◽  
Author(s):  
Antía Gómez Armesto ◽  
Lucía Bibián-Núñez ◽  
Claudia Campillo-Cora ◽  
Xabier Pontevedra-Pombal ◽  
Manuel Arias-Estévez ◽  
...  
Keyword(s):  
Temperate Forest ◽  
Aggregate Size ◽  
Fine Sand ◽  
Soil Aggregate ◽  
Coarse Sand ◽  
Coarse Silt ◽  
Fine Silt ◽  
Size Fractions ◽  
Total Hg ◽  
Sand Size

This study determined the distribution of total Hg (Hg<sub>T</sub>) among aggregate size fractions in the A, E, Bh and Bs horizons of a representative temperate forest podzol. The aggregate distribution was dominated by the coarse sand size fraction (average of 55%) followed by fine sand (29%), fine silt (10%), coarse silt (4%) and clay (2%). In general, Hg<sub>T</sub> mean values increased as the aggregate size become smaller: clay (170 ng g<sup>-1</sup>) &gt; fine silt (130 ng g<sup>-1</sup>) &gt; coarse silt (80 ng g<sup>-1</sup>) &gt; fine sand (32 ng g<sup>-1</sup>) &gt; coarse sand (14 ng g<sup>-1</sup>). Total Hg enrichment in clay-sized aggregates ranged from 2 to 11 times higher than the values shown by the bulk soil (&lt; 2 mm). The accumulation of Hg<sub>T</sub> in the finer size aggregates was closely related to total organic C, Na-pyrophosphate extracted C, metal (Al, Fe)-humus complexes and Al and Fe oxyhydroxides. Indeed, these parameters varied significantly (<em>p </em>&lt; 0.05) with the aggregate size and their highest values were found in the finer fractions. This suggested the role of these soil compounds in the increase of the specific surface area per mass unit and negative charges in the smallest aggregates, favouring Hg retention. Mercury accumulation factor (Hg<sub>AF</sub>) values reached up to 10.8 in the clay size aggregates, being close to 1 in sand size fractions. Regarding Hg enrichment factors (Hg<sub>EF</sub>), they were &lt; 4 (“moderate pollution” category) in most of the horizons and aggregate sizes. Grain size mass loading (GSF<sub>Hg</sub>) revealed that finer fractions had a higher Hg loading than their mass fractions, with a notable contribution of fine silt which made up &gt; 50% of Hg<sub>T</sub> in Bh and Bs horizons. The potential ecological risk index (PERI<sub>Hg</sub>) increased as the aggregate size decreased, with the highest values in the illuvial horizons (45-903) and lowest in the E horizon (3-363). Heterogeneous distribution of Hg in the soil aggregate size fractions must be considered for Hg determination for purposes such as critical loads, background values or environmental risk indices. In addition, Hg accumulation in finer aggregates could be of concern due to its potential mobility in forest soils, either transferred by leaching to groundwater and freshwaters or mobilized by runoff in surface horizons.

A STUDY OF THE MINERALOGICAL COMPOSITION OF SAND IN SOUTHERN ONTARIO

1959 ◽  
Vol 39 (2) ◽  
pp. 185-196 ◽  
Author(s):  
Carol I. Dell
Keyword(s):  
Mineralogical Composition ◽  
Fine Sand ◽  
Coarse Sand ◽  
Heavy Minerals ◽  
Plant Nutrient ◽  
Coarse Silt ◽  
Medium Sand ◽  
Sand Fraction ◽  
Southern Ontario ◽  
Mineralogical Study

A mineralogical study of the fine sand fraction of unweathered tills and stratified sands chosen to represent the deposits of the major ice lobes of southern Ontario was carried out. In addition, a few analyses were made of the coarse silt and coarser sands.In general there was the same variety of minerals in all samples and they varied only in their proportions. Tills overlying Palaeozoic bedrock contained abundant carbonates and shale fragments constituting up to 70 per cent of some fine sands. In the coarse sands, carbonates and shale increased sharply. In the coarse silt and fine sand, feldspars were more abundant than quartz whereas in the medium and coarse sand the reverse was true. Quartz increased in quantity with increasing grain size and reached a maximum in the medium sand. Heavy minerals usually constituted less than 15 per cent of the fine sand. Some of the minerals present in the coarse silt and fine sand were not found in the coarser sands. Usually the order of abundance of the heavy minerals was: hornblende, garnet, micas, magnetite, pyroxenes and sphene. Epidote, rutile, apatite, tourmaline, staurolite, kyanite and others were also noted. A chart listing the plant nutrient elements found in these minerals was prepared.

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