scholarly journals Pedological Investigations of Pleistocene Glacial Drift Surfaces in the Central Yukon

2007 ◽  
Vol 40 (1) ◽  
pp. 29-37 ◽  
Author(s):  
C. A. S. Smith ◽  
C. Tarnocai ◽  
O. L. Hughes
Keyword(s):  
Boreal Forest ◽  
Small Proportion ◽  
Clay Content ◽  
Strong Relationship ◽  
Soil Horizons ◽  
Glacial Deposits ◽  
Skin Development ◽  
Local Areas ◽  
Forest Regions ◽  
Regional Landscape

ABSTRACT Distinct soil morphologies associated with three different ages of Quaternary glacial deposits are characterized and subsequently named. Properties which provide a basis for distinguishing these in the field include solum depth, B horizon colour, clay skin development, coarse fragment weathering and periglacial features. A strong relationship is evident between the clay content at depth and the age of soil. Low values of Na pyrophosphate-extractable Fe and Al confirm the absence of any active podzol-forming processes even within the reddest (5YR, 2.5YR) soil horizons. Wounded Moose paleosols are the preserved soils observed on pre-Reid Glaciation (.2-1.2 Ma) deposits which show strong paleoargillic horizon development with red colours, high clay content, and common periglacial modification. Diversion Creek paleosols are the preserved soils found on Reid (80-120 ka) glacial deposits which show moderate paleoargillic horizon development and resemble the contemporary Gray Luvisols of the mid and southern boreal forest regions of Canada. Stewart soils are the weakly developed Brunisols formed on stable landform surfaces of McConnell (14-30 ka) glacial deposits. The Wounded Moose and Diversion Creek paleosols, while found commonly in local areas, occupy only a small proportion of the regional landscape.

POTASSIUM STATUS OF SOME QUEBEC SOILS: K RELEASED BY NITRIC ACID AND SODIUM TETRAPHENYLBORON AS RELATED TO PARTICLE SIZE AND MINERALOGY

1984 ◽  
Vol 64 (1) ◽  
pp. 99-106 ◽  
Author(s):  
T. AL-KANANI ◽  
A. F. MacKENZIE ◽  
G. J. ROSS
Keyword(s):  
Nitric Acid ◽  
Ammonium Acetate ◽  
Clay Content ◽  
Mineralogical Composition ◽  
Strong Relationship ◽  
Crop Response ◽  
Surface Samples ◽  
K Fertilizer ◽  
Sodium Tetraphenylboron ◽  
K Release

The K release characteristics of surface samples from five Quebec soils were investigated. Each soil was fractionated by size into six separates. Each separate was extracted with 1 M ammonium acetate (NH4OAc), with 1 M nitric acid (HNO3) and with sodium tetraphenylboron (NaTPB) and the K extracted was determined. The clay separates contained most of the HNO3 and NaTPB-extractable K. The average amounts of K removed by 1 M HNO3 and NaTPB from the clay was up to 16 times more than that released from silt or sand fractions. The strong relationship between extractable K and clay content was probably due to the similarity in mineralogical composition and degree of weathering of these soils. Clay-sized chlorite and vermiculite were destroyed by the HNO3 extraction but not by the NaTPB extraction. Crop response to K fertilizer was generally reduced as clay content and extractable K increased. Key words: Extractable K, NaTPB-K, HNO3-K

scholarly journals The implications of microbial and substrate limitation for the fates of carbon in different organic soil horizon types of boreal forest ecosystems: a mechanistically based model analysis

2014 ◽  
Vol 11 (16) ◽  
pp. 4477-4491 ◽  
Author(s):  
Y. He ◽  
Q. Zhuang ◽  
J. W. Harden ◽  
A. D. McGuire ◽  
Z. Fan ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Soil Carbon ◽  
Microbial Activity ◽  
Forest Ecosystems ◽  
Size Variation ◽  
Pool Size ◽  
Biogeochemical Processes ◽  
Soil Horizons ◽  
Carbon Decomposition ◽  
Decomposition Models

Abstract. The large amount of soil carbon in boreal forest ecosystems has the potential to influence the climate system if released in large quantities in response to warming. Thus, there is a need to better understand and represent the environmental sensitivity of soil carbon decomposition. Most soil carbon decomposition models rely on empirical relationships omitting key biogeochemical mechanisms and their response to climate change is highly uncertain. In this study, we developed a multi-layer microbial explicit soil decomposition model framework for boreal forest ecosystems. A thorough sensitivity analysis was conducted to identify dominating biogeochemical processes and to highlight structural limitations. Our results indicate that substrate availability (limited by soil water diffusion and substrate quality) is likely to be a major constraint on soil decomposition in the fibrous horizon (40–60% of soil organic carbon (SOC) pool size variation), while energy limited microbial activity in the amorphous horizon exerts a predominant control on soil decomposition (>70% of SOC pool size variation). Elevated temperature alleviated the energy constraint of microbial activity most notably in amorphous soils, whereas moisture only exhibited a marginal effect on dissolved substrate supply and microbial activity. Our study highlights the different decomposition properties and underlying mechanisms of soil dynamics between fibrous and amorphous soil horizons. Soil decomposition models should consider explicitly representing different boreal soil horizons and soil–microbial interactions to better characterize biogeochemical processes in boreal forest ecosystems. A more comprehensive representation of critical biogeochemical mechanisms of soil moisture effects may be required to improve the performance of the soil model we analyzed in this study.

Subsoil hydraulic conductivity estimates for the Lower Macquarie Valley

Soil Research ◽  
1996 ◽  
Vol 34 (2) ◽  
pp. 213 ◽  
Author(s):  
TL Bird ◽  
TM Willis ◽  
GJ Melville
Keyword(s):  
Hydraulic Conductivity ◽  
Irrigation Water ◽  
Clay Content ◽  
Strong Relationship ◽  
Saturated Hydraulic Conductivity ◽  
Deep Drainage ◽  
Soil Variation ◽  
Constant Head ◽  
Semi Empirical ◽  
Soil Groups

Field saturated hydraulic conductivity was measured in situ, at two depths in the B horizon, on irrigated soils in the Lower Macquarie Valley. Measurements were made with constant head well permeameters, using the single-head method, and water of moderate sodicity and high salinity. The hydraulic conductivity data were log-normally distributed for all soil groups and there were significant differences between some of these soil groups in mean hydraulic conductivity. Three soils exhibited significant differences in mean hydraulic conductivity between depths. Hydraulic conductivity measurements ranged up to 3 orders of magnitude within a soil. Variation in hydraulic conductivity estimates, both between and within soil groups, confirmed the variation observed in previous predictions of deep drainage, which were obtained using a semi-empirical model. A cluster analysis on hydraulic conductivity indicated that similar morphological soil properties did not necessarily reflect similar hydrologic properties. There was a strong relationship between hydraulic conductivity and exchangeable sodium percentage (ESP), hydraulic conductivity and clay content, and ESP and clay content. A model was developed to predict field saturated hydraulic conductivity from ESP and clay content data. Hydraulic conductivity measured in this study may not have been representative of percolation rates which would occur with low salinity irrigation water, but can be used to assess the risk of recharge from irrigation on different soils in the lower Macquarie Valley. Shallow watertables may potentially develop when the application of irrigation water greatly exceeds crop water requirements. Quantification of groundwater recharge will allow the likelihood of shallow watertable development in the Lower Macquarie Valley to be assessed.

A warmer climate reduces the bioreactivity of isolated boreal forest soil horizons without increasing the temperature sensitivity of respiratory CO2 loss

2015 ◽  
Vol 84 ◽  
pp. 177-188 ◽  
Author(s):  
Jérôme Laganière ◽  
Frances Podrebarac ◽  
Sharon A. Billings ◽  
Kate A. Edwards ◽  
Susan E. Ziegler
Keyword(s):  
Boreal Forest ◽  
Forest Soil ◽  
Temperature Sensitivity ◽  
Soil Horizons

Reworked Middle Wisconsinan (?) plant fossils from the Brampton Esker, southern Ontario

1977 ◽  
Vol 14 (3) ◽  
pp. 426-430 ◽  
Author(s):  
P. F. Karrow ◽  
W. Harrison ◽  
H. C. Saunderson
Keyword(s):  
Boreal Forest ◽  
Radiocarbon Date ◽  
Glacial Deposits ◽  
Radiocarbon Dates ◽  
Southern Ontario ◽  
Plant Fossils ◽  
Gravel Pit

Plant fossils, consisting of abraded pieces of wood, seeds, and pollen, occur near the bottom of the Armbro gravel pit in a till-capped esker near Brampton, Ontario. A radiocarbon date suggests a Mid-Wisconsinan age for the wood, whereas stratigraphic evidence suggests a Port Huron age for the enclosing sediments. The plant fossils indicate conditions similar to those now found in the southern boreal forest. Derivation of the plants from buried Middle Wisconsinan interstadial sediments to the southeast is suggested.Plant remains in glacial deposits should normally be assumed to be reworked; radiocarbon dates on such fossils do not date the enclosing sediment.

Adsorption Characteristics of Atrazine and Alachlor in Kansas Soils

Weed Science ◽  
1995 ◽  
Vol 43 (3) ◽  
pp. 461-466 ◽  
Author(s):  
Leticia S. Sonon ◽  
A. Paul Schwab
Keyword(s):  
Organic Carbon ◽  
Distribution Coefficient ◽  
Linear Function ◽  
Soil Depth ◽  
Equilibrium Concentration ◽  
Clay Content ◽  
Adsorption Coefficient ◽  
Soil Horizons ◽  
Adsorption Affinity ◽  
Different Soils

The adsorption of atrazine and alachlor was studied on samples of three horizons from soils with different textures and organic carbon contents. Soils were equilibrated with five concentrations of atrazine and alachlor using batch techniques. Adsorption affinity for atrazine and alachlor was approximated by the Freundlich constant (Kf), distribution coefficient (Kd), and the normalizedKdbased on organic carbon (Koc). Adsorption was not significantly correlated with soil depth, clay content, or organic carbon. Atrazine adsorption was a linear function of equilibrium concentration for nearly all soil horizons but was nonlinear in most horizons for alachlor. The extent of atrazine adsorption was greater in all horizons of the fine-textured soils (Kd= 1.5 to 5.5) compared to coarse-textured soils (Kd= 0.40 to 0.87). The same general trends with texture were not apparent for alachlor. Conversion ofKdtoKocfailed to reduce the variability in the linear adsorption coefficient for atrazine and alachlor in the different soils of this study.

scholarly journals Considerations for Selecting Potassium Placement Methods in Soil

2020 ◽  
pp. 341-362
Author(s):  
Michael J. Bell ◽  
Antonio P. Mallarino ◽  
Jeff Volenec ◽  
Sylvie Brouder ◽  
David W. Franzen
Keyword(s):  
Clay Content ◽  
Root Proliferation ◽  
Soil Horizons ◽  
Fertilizer Placement ◽  
Placement Decisions ◽  
Fertilized Soil ◽  
Research Findings ◽  
Moisture Conditions ◽  
System Characteristics ◽  
Rotation Sequence

AbstractPlacement strategies can be a key determinant of efficient use of applied fertilizer potassium (K), given the relative immobility of K in all except the lightest textured soils or high rainfall environments. Limitations to K accessibility by plants caused by immobility in the soil are further compounded by the general lack of K-stimulated root proliferation in localized soil zones enriched with K alone, compared with root proliferation due to concentrated N and P. Further, effects of K fixation reactions in soils with certain clay mineralogies and the declining concentration and activity of soil solution K with increasing clay content can also limit plant K acquisition. Variation in root system characteristics among crops in a rotation sequence and fluctuating soil moisture conditions in fertilized soil horizons in rain-fed systems increase the complexity of fertilizer placement decisions to ensure efficient K recovery and use. This complexity has resulted in extensive exploration of fertilizer K application strategies, with this chapter focusing on K applications to the soil. Issues discussed include comparisons of broadcast versus banded applications, depth of fertilizer placement, and the impacts of co-location of K with other nutrients. While research findings are often specific to the crop, soil, and seasonal conditions under which they are conducted, we attempt to identify strategies that most consistently deliver improved crop recovery and utilization of fertilizer K.

scholarly journals Predicting Phosphorus Desorption from Acid Piedmont Rice Soils of Bangladesh

2010 ◽  
pp. 50-60
Author(s):  
MA Islam ◽  
MA Saleque ◽  
AJMS Karim ◽  
ARM Solaiman ◽  
ABS Sarker
Keyword(s):  
Organic Carbon ◽  
Clay Content ◽  
Strong Relationship ◽  
Phosphorus Release ◽  
Good Prediction ◽  
Rice Soils ◽  
Soil Variables ◽  
Phosphorus Desorption ◽  
Almost All ◽  
P Desorption

A laboratory experiment was conducted at the Bangladesh Rice Research Institute, Gazipur during 2003 to determine phosphorus (P) desorption characteristics for 10 acid piedmont rice soils of Bangladesh. Soil samples were analyzed for sand, silt and clay, pH, organic carbon, available P, Mehlich-3 (M3) extractable P and dithionite extractable Fe (FeD). Desorption of phosphorus (release pattern) from different soils varied from 1.34 to 19.17 ppm. Phosphorus desorption was affected by the increased shaking time up to one hour. In almost all the studied soils, the highest desorbed P was extracted at one hour shaking time, beyond which there was again re-adsorption in most of the soils. Soil properties, particularly, pHKCl, ?pH, organic carbon and clay content were found to be important soil variables in determining phosphorus desorption in piedmont soils. The increase in ?pH and organic carbon increased P desorption, while an increase in clay and Fe tended to decrease in P desorption. Equations were proposed for predicting ?, ?, and K of famous Sharpley’s equation and were tested for better prediction of P desorption in Piedmont soils of Bangladesh. Sharpley’s equations for Piedmont soils resulted in a strong relationship (R2 = 0.86) between measured and predicted P desorption. The equations recommended by Sharpley to predict values for ?, ? and K has provided a good prediction of P desorption for our Piedmont rice soils.

A multi-sensor lidar, multi-spectral and multi-angular approach for mapping canopy height in boreal forest regions

2012 ◽  
Vol 121 ◽  
pp. 458-471 ◽  
Author(s):  
David J. Selkowitz ◽  
Gordon Green ◽  
Birgit Peterson ◽  
Bruce Wylie
Keyword(s):  
Boreal Forest ◽  
Canopy Height ◽  
Forest Regions

Distribution of cadmium, lead and zinc amongst the marine sediments, seagrasses and fauna, and the selection of sentinel accumulators, near a lead smelter in South Australia

1986 ◽  
Vol 37 (5) ◽  
pp. 567 ◽  
Author(s):  
TJ Ward ◽  
RL Correll ◽  
RB Anderson
Keyword(s):  
South Australia ◽  
Clay Content ◽  
Strong Relationship ◽  
Trophic Levels ◽  
Marine Animal ◽  
Sample Collection ◽  
Lead Smelter ◽  
Lead And Zinc ◽  
High Concentrations ◽  
Cadmium Lead

The concentrations of Cd, Pb and Zn in 23 species of marine animal and three species of seagrass were determined from samples collected near a large lead smelter. The spatial patterns of metal distribution in sediments, seagrasses, crustaceans and fish could be described in terms of distance from the smelter, although the fit of the mathematical model was often improved by the inclusion of other environmental variables, such as clay content of the sediment or time of sample collection. In the fish and seagrasses, Zn was the most widely dispersed metal, followed by Cd, then Pb, which was least dispersed. In general, organisms at higher trophic levels (fish) had lower metal concentrations than primary producers (seagrass). There was evidence for bioaccumulation of metals in many species, especially in the molluscs, but no biomagnification of any metal could be detected. The strong relationship between distance and metal content of several species of seagrass, fish and crustacean indicates that they are potential sentinel accumulators for monitoring the distribution of Cd, Pb and Zn. Although bivalve molluscs contained high concentrations of Cd, Pb and Zn, their contents did not consistently relate to distance from the smelter, suggesting that, except for Pinna bicolor, they are of little value as sentinel accumulators for these metals. The implications of the results for the design of monitoring programs using sentinel accumulators are discussed.

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