Queens Catena Soil Lab Report

Categories: Physics

Report, Pages 7 (1574 words)

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Introduction

The Queens Catena soils, located in the Elmsdale area, experience a cold and temperate climate with substantial annual rainfall. The average annual temperature is 6.4 °C, and the area receives approximately 1355 mm of precipitation annually (Climate Data, 2019). These soils are primarily composed of reddish-brown clay loam till, derived from red shales, mudstone, and sandstone fragments (Government of Canada, 2019). The predominant tree species in this region are red maple, black spruce, and birch. Due to the high precipitation levels, the soils are typically wet throughout most of the year, resulting in imperfect drainage.

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Tree roots infiltrate both soil horizons, giving rise to distinctive soil characteristics, including a greyish A horizon and a deeper reddish and stony B horizon.

Site Description

The soil sample site is situated on private property within a young woodlot surrounded by agricultural fields in Elmsdale, Nova Scotia. The GPS coordinates for the site are 20T UTM 0464764 4987203. Soil sampling was conducted on October 13th, 2019, with a recorded temperature of 13⁰C.

The weather conditions on that day were cloudy with light showers (>1mm) and light winds from the SSW at 5-10mph. Vegetation at the site includes goldenrod, wild strawberry, grass, moss, fern, birch, spruce, and maple. Leaf litter covers the ground, along with approximately 5-10% woody debris. The site is positioned at the crest of a gentle slope, as illustrated in Appendix IV. During excavation, various worms and bugs were observed. The soil's moderate stoniness occasionally hindered the digging process. Given the climatic, topographic, and biotic conditions, along with the presence of glaciated till, it appears that all the essential soil-forming factors are present to develop a fertile soil.

This report aims to correlate these factors with the results of various tests to determine the soil classification.

Soil Profile

The soil profile consists of two main horizons: the A horizon and the B horizon. The A horizon is characterized by a greyish color, while the B horizon is deeper and reddish, exhibiting mottled and stony features.

Discussion and Interpretation of Results

It is essential to approach the results with caution due to missing data, particularly the Na+ content in the B horizon, which could not be obtained due to equipment issues. Additionally, some tests were conducted over a 2-month period, which exceeds the usual retention time for certain analyses.

pH and Conductivity

The soil's pH was slightly acidic, with readings of 4.47 in the A horizon and 4.49 in the B horizon. Soil acidity increases with higher hydrogen ion concentrations. These results align with the geological composition of the soil, which has parent material from red shales. Some sedimentary rocks, such as shale, can contain sulfides, which, when hydrated and oxidized, produce sulfuric acid.

The conductivity of the A horizon was measured at 420μs, while the B horizon recorded 92.5μs. Conductivity is strongly associated with soil particle size and texture. It varies depending on the moisture content held by soil particles, with clays having high conductivity, silts exhibiting medium conductivity, and sands showing low conductivity. The substantial difference in conductivity between the A and B horizons could be attributed to their differing textures.

Cation Exchange Capacity

There is a notable difference in cation exchange capacity between the A and B horizons (Appendix II). This difference is likely due to nutrient uptake by plants in the A horizon. The A horizon also contains a significant amount of Mg++. The presence of magnesium in the A horizon can be attributed to leaching, facilitated by its large hydrated radius and weak bond to exchange sites in the soil. Competition from Ca++ and K+ can also reduce Mg++ uptake by plants.

Potassium

Potassium concentrations in the A horizon were measured at 270g/mL, while the B horizon exhibited a lower concentration of 80g/mL. This discrepancy is likely a result of the higher organic content in the A horizon. Potassium is a vital nutrient for plant growth, which may explain its higher concentration in the A horizon.

Organic Carbon

Soil organic carbon plays a crucial role in soil fertility, nutrient release for plant growth, soil structure support, and overall soil health. In this case, the A horizon displayed no organic carbon, while the B horizon contained 26.52mg/g or 2.65% organic carbon. The absence of organic carbon in the A horizon could be due to leaching, influenced by the fluctuating water table resulting from seasonal rainfall. Additionally, mottling was observed within the soil profile.

Moisture Content

The moisture content at field capacity was found to be 43.25% in the A horizon and 48.5% in the B horizon. This difference can be attributed to the higher clay content in the B horizon, allowing it to retain more water. The moisture content by volume in the A horizon was 19%, compared to 11% in the B horizon. The percent moisture by dry weight was 39% for the A horizon and 33% for the B horizon. The inconsistent soil moisture content can be attributed to the soil's imperfect drainage.

Soil Classification

The soil classification for this site falls under the Podzolic order. According to this classification, most Podzolic soils have a reddish-brown to black B horizon, which matches the reddish-brown B horizon observed in this study. At the Great Group level, this Podzol is likely classified as a Humo-Ferric Podzol (HFP). The A horizon's lighter tone and the B horizon's visible red band, transitioning to darker brown with depth, align with the characteristics of a Humo-Ferric Podzol. The reddish-brown Podzolic B horizons are characterized by higher iron content relative to organic matter and are classified as Bf horizons (iron = Fe). Additionally, this soil exhibits a substantial amount of mottling, indicating a gleyed subgroup, as defined by the presence of distinct to prominent mottles within 1 meter of the mineral surface of the soil.

This soil can be further classified as a slightly gravelly loamy sand based on its texture class. Given its sand content, low pH, and imperfect drainage, this soil is not suitable for agriculture. Consequently, the landowner has converted the area into a young tree lot, which can help improve the soil by enhancing cation exchange capacity, organic carbon content, nutrient supply, and water movement within the soil.

Texture Triangle Classification

The texture triangle classification for this soil is as follows:

A horizon: Loamy sand
B horizon: Sandy loam

Conclusion

In conclusion, the analysis of the Queens Catena soil profile provides valuable insights into its characteristics and classification. The soil exhibits distinctive features, such as its slightly acidic pH, conductivity variations between the A and B horizons, and significant differences in cation exchange capacity. These characteristics are a result of the geological composition and the influence of vegetation in the region.

The classification of the soil as a Podzolic order, specifically a Humo-Ferric Podzol (HFP), is consistent with its reddish-brown B horizon, rich in iron relative to organic matter. The presence of mottling also suggests a gleyed subgroup within the soil.

Notably, the soil's unsuitability for agriculture, due to its sandy texture, low pH, and imperfect drainage, has led the landowner to convert the area into a young tree lot. This decision aligns with the need to improve the soil's quality. Trees can contribute to enhancing cation exchange capacity, increasing organic carbon content, improving nutrient supply, and aiding in water movement within the soil.

Overall, this study highlights the complex interplay of geological, climatic, and biotic factors in soil formation. Understanding these factors is crucial for land management decisions and sustainable land use practices in the Elmsdale region and similar environments.

Appendices

Appendix I

Data Table

Units	A Horizon	B Horizon
Sand %	75	61.48
Silt %	25	37.72
Clay %	0	0.8
Db (g/mL)	1.11	1.47
Dp (g/mL)	2.78	2.38
Porosity %	60	64
C.E.C. Cmolc/kg	30.02	5.28
Ca++ (mg/L as Ca++)	120	0
Mg++ (mg/L as Mg++)	160	30
Na+ (g/mL)	85.3 *	*
K+ (g/mL)	270	80
Al+++ (g/mL)	1.02	6.6
pH	4.47	4.49
Conductivity (μs)	420	92.5
% Moisture by dry weight %	19	11
% Moisture by volume %	39	33
% Mweight at field capacity %	43.29	48.5
% Hygroscopic water %	*	*
Organic Carbon (mg/g)	0	26.52