scholarly journals Influence of low temperatures on aggregate disruption of heavy clay soils

2010 ◽  
Vol 58 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Jana Kozlovsky Dufková
Keyword(s):  
Wind Erosion ◽  
Freeze Drying ◽  
Soil Aggregates ◽  
Early Spring ◽  
Clay Soils ◽  
Late Winter ◽  
Freezing And Thawing ◽  
Heavy Clay ◽  
Frozen Clay ◽  
Erodible Fraction

Heavy clay soils that are normally resistant to wind erosion, from study site Ostrožská Nová Ves si­tua­ted in the foothills of the Bílé Karpaty Mountains, Czech Republic, were a subject of laboratory analyses. The analyses should found out the influence of overwinter processes on disruption of soil aggregates and thus reason of vulnerability to soil loss by wind. Two overwinter processes were observed – freezing and thawing, and freeze-drying of the soil. Both processes have indicated the increasing of erodible fraction in dependence of water content of analysed soils. Exposed frozen clay soils that freeze-dries during the winter in the foothills of Bílé Karpaty, leaves soils highly erodible in late winter and early spring.

Freeze-drying processes and wind erodibility of a clay loam soil in southern Alberta

1999 ◽  
Vol 79 (1) ◽  
pp. 127-135 ◽  
Author(s):  
Murray S. Bullock ◽  
Francis J. Larney ◽  
Sean M. McGinn ◽  
R. César Izaurralde
Keyword(s):  
Water Content ◽  
Vapour Pressure ◽  
Wind Erosion ◽  
Freeze Drying ◽  
Northern Great Plains ◽  
Clay Loam ◽  
Clay Loam Soil ◽  
Canadian Prairie ◽  
Loam Soil ◽  
Erodible Fraction

Freeze-drying has been implicated as a factor causing soil aggregate breakdown on the Canadian Prairies and northern Great Plains. Aggregates of a Dark Brown Chernozemic clay loam soil sampled in October 1993 and January and April 1994 were subjected to repeated cycles of wetting (to 0.1, 0.2 and 0.3 kg kg−1 water contents) freezing, and freeze-drying under laboratory conditions. The October 1993 samples showed less disruption when initially exposed to freeze-drying cycles compared to samples taken in January and April 1994. Using regression analysis, we predicted that 31 freeze-dry cycles were required for the 0.1 kg kg−1 water content aggregates to reach 60% erodible fraction (EF, % aggregates <0.86 mm), 9 cycles for the 0.2 kg kg−1 aggregates and 2 for 0.3 kg kg−1 aggregates. In a field study, conducted over the 1994–1995 winter on a similar clay loam soil, we estimated the number of freeze-drying cycles using large vapour pressure (VPL) and small vapour pressure (VPS) gradients between the soil surface (which had a mean winter water content of ~0.1 kg kg−1) and the atmosphere. With solar energy adjustments, we predicted that the number of freeze-dry cycles required for the soil to reach 60% EF was 60 for VPL and 37 for VPS conditions. The latter number was similar to the 31 cycles predicted in the laboratory study of aggregates at 0.1 water content. Our results demonstrate that freeze-drying is an important overwinter process in the breakdown of soil aggregates and hence wind erosion risk in the Canadian prairie region. Key words: Freeze-drying, wind erosion, erodible fraction

scholarly journals Determination of wind erosion intensity on heavy clay soils

2010 ◽  
Vol 58 (2) ◽  
pp. 155-160
Author(s):  
Jana Kozlovsky Dufková ◽  
Vladan Jareš ◽  
Petr Húsek
Keyword(s):  
Soil Loss ◽  
Wind Erosion ◽  
Clay Soils ◽  
Soil Erodibility ◽  
Clay Particles ◽  
Heavy Clay ◽  
Deep Soils ◽  
Soil Losses ◽  
Erosion Intensity

Wind erosion, common problem of light-textured soils, was determined on heavy clay soils in the foothills of Bílé Karpaty Mountains, Czech Republic. Soil erodibility by wind was determined from the Map of potential erodibility of soil by wind and from the calculation of potential and real soil loss by wind. All the determinations show underestimation of soil erodibility by wind on heavy clay soils, because methods that are used for this are based above all on the assessment of clay particles content and the presumption the more clay particles soil contains, the less vulnerable to wind erosion is. The potential erodibility of soil by wind is 0,09 t . ha−1 per year. The determined value does not exceed the tolerable soil loss limit 10 t . ha−1 per year for deep soils. The real average erodibility of soil by wind has the highest value 1,47 g . m−2 on November 30th, 2008. Other soil losses that do not exceed the tolerable soil loss limit 1,4 g . m−2, were determined on March 18th and 28th, 2008. Big difficulties come with the assessment of the erodibility of heavy clay soils in the areas, where soil erosion ve­ri­fia­bly exists, but it is not assessable by objective calculating methods. Evident necessity of new know­ledge concerning the determination of wind erosion intensity follows from the results.

scholarly journals TO THE DEFINITION OF DEFORMATION CHARACTERISTICS OF SOILS IN TERMS OF SEASONAL FREEZING AND THAWING

2016 ◽  
Vol 3 (2) ◽  
pp. 87-89
Author(s):  
Александра Мащенко ◽  
Aleksandra Mashchenko
Keyword(s):  
Physical Characteristics ◽  
Clay Soils ◽  
Deformation Characteristics ◽  
Freezing And Thawing ◽  
Seasonal Freezing ◽  
Deformation Properties ◽  
Frozen Clay ◽  
Definition Of

The article presents the method of determining the deformation properties of soils thaw as well as results of the physical characteristics of frozen clay soils and silty sands. The results of the coefficient of compressibility and thawing during thawing soils are given. The article presents the methods for improvement of deformation properties of soils. Keywords: coefficient of thawing, compressibility when thawing, clay soils, silty sands, reinforcement

scholarly journals Using the equation for computing the wind erodible fraction of soils in the conditions of the Czech republic

2021 ◽  
Vol 24 (1) ◽  
pp. 63-70
Author(s):  
Jana Kozlovsky Dufková ◽  
Vít Procházka ◽  
Jan Szturc ◽  
Tomáš Mašíček
Keyword(s):  
Czech Republic ◽  
Calcium Carbonate ◽  
Wind Erosion ◽  
Soil Aggregates ◽  
The Czech Republic ◽  
The Usa ◽  
Statistical Program ◽  
Southern Moravia ◽  
New Equation ◽  
Erodible Fraction

Abstract The erodible fraction (EF) of soil (soil aggregates and particles <0.84 mm) is one of the basic factors according to which the susceptibility of soil to wind erosion can be assessed. The standard method for determining the EF content is the use of a rotary sieve. Nevertheless, its availability is limited by its price and the fact that it is not mass-produced and is necessary to build the sieve to order. An alternative method of determining the EF content is to use an equation based on knowledge of the content of sand, silt, clay, organic carbon, and calcium carbonate. However, this equation has only been tested for US conditions. Therefore, the research focuses on the validation of the equation for the conditions of the Czech Republic, specifically in the territory of Southern Moravia. The results show that the equation validated for the USA cannot be used to determine the EF content in soils of the Czech Republic. Using the statistical program Unistat©, a new equation was proposed with correlation coefficient R = 0.8238 which means good applicability of the equation for the local soils at least in the area of Southern Moravia.

Seasonal activity and estivation of lumbricid earthworms in the midlands of Tasmania

Soil Research ◽  
1994 ◽  
Vol 32 (6) ◽  
pp. 1355 ◽  
Author(s):  
RB Garnsey
Keyword(s):  
Soil Moisture ◽  
Adult Development ◽  
Survival Rates ◽  
Soil Surface ◽  
Early Spring ◽  
Lumbricus Rubellus ◽  
Late Winter ◽  
Cocoon Production ◽  
Density And Biomass ◽  
Earthworm Activity

Earthworms have the ability to alleviate many soil degradational problems in Australia. An attempt to optimize this resource requires fundamental understanding of earthworm ecology. This study reports the seasonal changes in earthworm populations in the Midlands of Tasmania (<600 mm rainfall p.a.), and examines, for the first time in Australia, the behaviour and survival rates of aestivating earthworms. Earthworms were sampled from 14 permanent pastures in the Midlands from May 1992 to February 1994. Earthworm activity was significantly correlated with soil moisture; maximum earthworm activity in the surface soil was evident during the wetter months of winter and early spring, followed by aestivation in the surface and subsoils during the drier summer months. The two most abundant earthworm species found in the Midlands were Aporrectodea caliginosa (maximum of 174.8 m-2 or 55.06 g m-2) and A. trapezoides (86 m-2 or 52.03 g m-2), with low numbers of Octolasion cyaneum, Lumbricus rubellus and A. rosea. The phenology of A. caliginosa relating to rainfall contrasted with that of A. trapezoides in this study. A caliginosa was particularly dependent upon rainfall in the Midlands: population density, cocoon production and adult development of A. caliginosa were reduced as rainfall reduced from 600 to 425 mm p.a. In contrast, the density and biomass of A. trapezoides were unaffected by rainfall over the same range: cocoon production and adult development continued regardless of rainfall. The depth of earthworm aestivation during the summers of 1992-94 was similar in each year. Most individuals were in aestivation at a depth of 150-200 mm, regardless of species, soil moisture or texture. Smaller aestivating individuals were located nearer the soil surface, as was shown by an increase in mean mass of aestivating individuals with depth. There was a high mortality associated with summer aestivation of up to 60% for juvenile, and 63% for adult earthworms in 1993 in the Midlands. Cocoons did not survive during the summers of 1992 or 1994, but were recovered in 1993, possibly due to the influence of rainfall during late winter and early spring.

Field Performance of Five Soil Moisture Instruments in Heavy Clay Soils

2014 ◽  
Vol 79 (1) ◽  
pp. 20-29 ◽  
Author(s):  
E. RoTimi Ojo ◽  
Paul R. Bullock ◽  
John Fitzmaurice
Keyword(s):  
Soil Moisture ◽  
Field Performance ◽  
Clay Soils ◽  
Heavy Clay

TEMPERATURE RESISTANCE OF GOLDFISH MAINTAINED UNDER CONTROLLED PHOTOPERIODS

1959 ◽  
Vol 37 (4) ◽  
pp. 419-428 ◽  
Author(s):  
William S. Hoar ◽  
G. Beth Robertson
Keyword(s):  
Temperature Change ◽  
Seasonal Variations ◽  
Rapid Growth ◽  
Endocrine System ◽  
Early Spring ◽  
Late Winter ◽  
Thyroid Activity ◽  
Temperature Resistance ◽  
Sudden Temperature Change

Goldfish maintained under controlled photoperiods for 6 weeks or longer were relatively more resistant to a sudden elevation in temperature when the daily photoperiods had been long (16 hours) and relatively more resistant to sudden chilling when they had been short (8 hours). The magnitude of the effect varied with the season. Thyroid activity was slightly greater in fish maintained under the shorter photoperiods. The longer photoperiods stimulated more rapid growth of ovaries during late winter and early spring. The endocrine system is considered a link in the chain of events regulating seasonal variations in resistance to sudden temperature change.

Leaf spot and dry rot of lettuce caused by Xanthomonas vitians (Brown) Dowson

1963 ◽  
Vol 14 (6) ◽  
pp. 778 ◽  
Author(s):  
DE Harrison
Keyword(s):  
Leaf Spot ◽  
Early Spring ◽  
Late Winter ◽  
Laboratory Studies ◽  
Dry Rot ◽  
Complete Destruction ◽  
Western Victoria ◽  
Valley Area ◽  
North Western

During the late winter and early spring of 1960, and again to a lesser extent in 1961 and 1962, many lettuce crops in the Murray Valley area of north-western Victoria were seriously affected by a disease characterized by blackening, dry rotting, and collapse of the affected leaves. The incidence of disease varied from about 10% up to practically complete destruction of some plantings. A yellow bacterium was consistently isolated from affected plants and proved to be pathogenic to lettuce. Laboratory studies have shown that the organism agrees closely with the recorded description of Xanthomonas vitians (Brown) Dowson, which has not, apparently, been previously studied in Australia.

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