GEOG 3360 Lecture Notes - Cation-Exchange Capacity, Soil Horizon, Clay Minerals

32 views6 pages
Published on 20 Apr 2013
School
York University
Department
Geography
Course
GEOG 3360
Professor
YORK UNIVERSITY
Lab 2-Cation Exchange Capacity
GEOG 3600
Paloma D'Silva
3/6/2013
By knowing the CEC of the clay-size fraction in soil, it is possible to find out clay minerals present. In this
report, the CEC per 100 g clay has been compared with the % C/100 g clay in order to find out what clay
minerals might be present in the soil.
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 6 pages and 3 million more documents.

Already have an account? Log in
1
Lab 2-Cation Exchange Capacity
1.0 Introduction
The CEC of a soil, or its cation exchange capacity, is the maximum ability of a soil to hold cations
available for exchange, and is expressed as milliequivalents/100 g soil. Various clay-size minerals
have CECs that fall within certain limits, and by knowing the CEC of the clay-sized fraction in the soil
it is possible to estimate the clay minerals present. CEC varies with clay mineral species, in addition
to organic matter content, and the higher the organic matter content of the soil, the higher CEC will
be (Birkeland, 1999). CEC is used to estimate the clay minerals present in the soil sample by making
use of soils' property to exchange cations. The soils data has been given for %C and CEC for 100g soil
and must be recalculated with respect to 100 g clay. The CEC has been taken as a <2mm fraction,
and recalculated with respect to the clay percentage in the soil samples.
2.0 Methods
In order to calculate the CEC and %C with respect to clay, it is done for 100g of soil. The soil
amount of 100 g clay is divided by the total clay percentage, and then multiplied by the
percentage of carbon to get %C per 100 g clay. Similarly, for CEC/100 g clay, the amount of 100
is divided by the clay percentage and then multiplied by CEC for the <2mm fraction per 100 g
soil, which has been expressed as a percentage in the soil profiles. The calculations have been
graphed for three soil profiles, Profile 44, Profile 99, and Profile 86. All data used here has been
obtained from pages 101-103 of GEOG 3600 course kit (Mahaney, 2013).
3.0 Results
3.1 Clay Mineral Calculations
Both CEC and %C (which represents organic matter content of the soil) have been calculated
as a fraction of 100 g and have been graphed in the corresponding soil profiles.
3.1.1 Profile 44
Table 1
Profile
44
Raw %C
Raw
CEC
%clay
CEC/100g
%C/100g
3.74
38.90
41
94.88
9.12
1.18
37.60
46.2
81.39
2.55
0.51
41.10
51.3
80.12
0.99
0.18
45.60
59.5
76.64
0.30
0.13
45.60
60.1
75.87
0.22
0.1
46.60
59
78.98
0.17
0.1
47.20
56.8
83.10
0.18
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 6 pages and 3 million more documents.

Already have an account? Log in

Document Summary

By knowing the cec of the clay-size fraction in soil, it is possible to find out clay minerals present. In this report, the cec per 100 g clay has been compared with the % c/100 g clay in order to find out what clay minerals might be present in the soil. The cec of a soil, or its cation exchange capacity, is the maximum ability of a soil to hold cations available for exchange, and is expressed as milliequivalents/100 g soil. Various clay-size minerals have cecs that fall within certain limits, and by knowing the cec of the clay-sized fraction in the soil it is possible to estimate the clay minerals present. Cec varies with clay mineral species, in addition to organic matter content, and the higher the organic matter content of the soil, the higher cec will be (birkeland, 1999).

Get OneClass Grade+

Unlimited access to all notes and study guides.

YearlyMost Popular
75% OFF
$9.98/m
Monthly
$39.98/m
Single doc
$39.98

or

You will be charged $119.76 upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.