ASPAC | Pacific network of soil laboratories: 1st meeting. Brisbane, Australia, 17 - 18 October 2019, Presenters: Lucrezia Caon, Nopmanee Suvannang

1. Soil and Plant Testing and Diagnostic
Laboratory
College of Natural and Applied Sciences
University of Guam
Mohammad H. Golabi, PhD
Soil and Environmental Scientist
Presented at the
ASPAC
(Pacific Soil Laboratory Network)
Brisbane, Australia
16-18 October, 2019

3. Federated States
of Micronesia
Google Earth image
Palau
Guam
CNMI
Marshal
l
Islands
Micronesi
a

4. Soils of Guam

5. Functions and Challenges for the Soil
and Plant Analysis Laboratories at
UOG

6. Soil & Plant Testing and Diagnostic Laboratory
Service and Functions:
1. Assist Scientist with their research projects by running their research samples.
2. Provide technical assistance to Scientists with their Labs
3. Provide valuable soil and plant analysis for the following:
Farmers,
Golf Courses,
Extension
Construction Companies,
Landscapers, and private contractors,
schools,
off-island clienteles,
4. Analyze Graduate student samples.
5. Provide guidance and services to local school students with science projects.
6. Assist and provide services to other agencies:
US Customs & Quarantine,
NRCS, for their off-island services and needs
Soil & Plant Testing Lab is the only Diagnostic Lab here in Guam and in the Western
Pacific.
Note: When samples are analyzed, Soil & Plant Testing Lab provide sample analysis data.
These data (numbers) will then have to be interpreted to the clients as to what do they
mean. This interpretation of the data numbers is done by Dr. Golabi to make sure that the
clients understand the information that is give to them

7. Methods and Procedures conducted
at the soil Labs

8. Routine Nutrient Analysis:
 Atomic Absorption Spectrometer (AA) Unit:
 Ca
 K
 Mg
 Cole Parmer Unit
 Available Phosphate
 Carbon Nitrogen Analyzer:
 Total Carbon
 Total Nitrogen
 Lachate Unit:
 Nitrate
 Orthophosphate
 Aluminum

9. Soil Lab Settings and Equipment

10. The AA machine
This Atomic Absorption unit is used to test for routine soil
sample analysis

11. Phosphate meter
This Cole Parmer Unit is used to measure the available
phosphate in the soil sample.

12. pH Meter
This unit is used to test for the soil pH

13. EC meter
This EC probe is used to read the electro-conductivity level
of the soil sample

14. FlashEA Carbon/Nitrogen Analyzer

15. Quik Chem Lachate instrument

16. Number of Samples and the extend of the
Services preformed at the UOG soil labs:
 We run samples anywhere between 500 to over a 1000 analysis per
year. This is counting all pH, %OM, available P, K, Ca, Mg, Ec, & Soil
Texture.
 In a routine analysis there are about six (6) different types of
analysis per sample (pH, %O.M., available P, K, Ca, & Mg).
 We run about 250 to 500 samples a year plus, minus about 100
samples.

17. Sample Analyzed since
January 2018
January 2018 to June 2018
Client
No. of
Samples
Type of
sample
Type of
Analysis pH
%
O.M.
Availabl
e P
Availabl
e K
Availabl
e Ca
Available
Mg CN Total Analysis
Manhita Farm 13 soil Routine X X X X X X X 104
LMS 6 soil Routine X X X X X X 36
Dr. Friday HI 24 soil Routine X X X X X X X 192
Dr. Friday Plant
Tissue 6 Plant Tissue X X X X X 36
LMS 4 Soil Routine X X X X X X X 32
Watts Co. 5 Soil Routine X X X X X X X 40
Brian LG. 1 Soil Routine X X X X X X 8
LMS 1 Compost Routine X X X X X X X 8
Roland Q 1 Frass Routine X X X X X X X 8
DR. Golabi 24 Soil Routine X X X X X X X 192
Dr. Golabi 216 Soil CN X 432
Sep-18 0 1088
October
Total Samples 301
Routine Sample analysis include: pH, % Organic Matter, Available P, K, Ca, Mg
CN is analyzed on a dry run using Carbon/Nitrogen Analyzer and data is reported in Total
Percent.
X = Indicates what type of test was done for the
sample
Note: Soil Labs: Soil Research lab and Soil & Plant Testing lab have also aided about three High School Students with their School Science Projects.
All have achieved high marks on their projects and have come in second and first places.

18. Other Supportive Functions (in addition to
supporting researchers) of the Soil Labs at UOG:
Training graduate, undergraduate as
well as Local School students

19. Undergraduate students
conducting assigned soil
analysis lab exercise.

20. High school students are
given the mentoring
opportunity to learn and
use the soil labs for their
science experiments
Mentoring local high school
students with their science
projects:

21. Some of the most common procedures
performed by the graduate/undergraduate
students at the UOG Soil Labs are the
following:

22. AL 380 Principles of Soil Science
Fall Semester 2018
Instructor: M.H. Golabi, PhD
Laboratory Exercise No. 8
SOIL REACTIONS – Soil pH
Introduction to Soil Acidity
Water (H2O) disassociates to hydrogen (H+
) and hydroxyl (OH-
) ions in the
following reaction:
H2O  H+
+ OH-
The concentrations of these two ions are what determine whether a solution is
acidic (a high concentration of H+
) or basic (a low concentration of H+
). The product of
the concentrations of H+
and OH-
is always 1 x 10-14
moles per liter. Therefore, if there is
1 x 10-7
moles/liter of H+
, there will be 1 x 10-7
moles/liter of OH-
and the solution is
neutral. The H+
, concentration will vary from 1 x 100
to 1 x 10-14
moles/liter.
Instead of always expressing the total concentration of H+
in solution, scientists
use the logarithmic scale to express the concentration. This scale is called the pH scale.
pH = Log 10 (1/H+
concentration)
Therefore, if there is 1 x 10-6
moles/liter of H+
, the pH is 6.0. If the H+
concentration is 1 x 10-8
moles/liter, the pH is 8.0. As the pH gets higher, there are less
H+
ions in solution and the solution is basic.
The pH of most soils ranges from 3.5 to 10.0. The attached figure shows the pH
scale and some of its effects on soil conditions for plant growth.
Soil contains several types of acidity. The active acidity is the H+
concentration
in the soil solution. Another source of soil acidity, called exchangeable acidity, is the
exchangeable aluminum and hydrogen ions, which are adsorbed on the negative
exchange sites. Exchangeable aluminum (Al3+
) is a source of acidity because of the
following hydrolysis reactions:
Al3+
+ H2O  AlOH+2
+ H+
AlOH+2
+ H2O  Al (OH)2
+
+ H+
Al (OH)2
+
+ H2O  Al (OH)3(solid gibbsite) + H+
The H+
in solution formed by these reactions then contributes to the active acidity.
EXERCISE 1. MEASURING SOIL PH
Equipment: Buffer standard solutions (pH 4, 7 and 10)
Specimen cups
Balance
pH meter
Glass stirring rods
pH color indicator kit
Three different soil samples
Laboratory Procedure for pH determination
1) Weigh 10.0 g of soil (use three different soil samples) into a sample cup.
2) Using a pipette or dispenser, add 10 ml of distilled water to obtain a 1:1soil: water
ratio. Stir with a glass rod.
3) Allow to stand for 10 minutes and stir again.
4) With the aid of a pH meter, measure the pH.
5) Repeat step 1 – 4 except add 10 ml of 1M KCl instead of water into the cup (use
another set of cup with new sets of soil samples). This step will illustrate the pH
measured with KCl extract as compared to pH measured with water extract.
Results:
pH
______________________________________________
Soil samples 1M KCl Water pH Indicator kit
Sample 1
Sample 2
Sample 3
Calculations:
pH = pHKCl - pHH2O
Where:
If pH < 0 then soil has net negative charge
If pH > 0 then soil has net positive charge
After determining the pH explain the charge characteristics of the soil that you
studied.

23. AL 380 Principles of Soil Science
Fall Semester 2018
Instructor: M.H. Golabi, PhD
Laboratory Exercise No. 8
MEASURING SOIL ORGANIC MATTER
Another method which is commonly used is based on the reaction of K2Cr2O7 and H2SO4
with organic carbon such that:
2 Cr2O7
-2
+ 3 C + 16 H+
 4 Cr+3
+ 3 CO2 + 8 H2O
In this reaction the Cr2O7
-2
is reduced to Cr+3
the more organic carbon that is present.
Excess Cr2O7
-2
is then titrated with FeSO4  7H2O or Fe (NH4)2(SO4)2  7H2O to a
standard endpoint. Several methods utilize this chemical reaction and vary in their use of
heating to insure complete oxidation of the organic carbon.
The Walkley-Black method does not use supplemental heating and therefore only
approximately 76% of the organic carbon is recovered. A correction factor of 1.3 is used
to account for incomplete oxidation of the organic carbon. Problems with the
dichromate-based methods include interferences from the presence of chloride; ferrous
iron and manganese oxides and the difficulty of disposing of toxic chemicals generated
using the method.
Calculations:
% Organic Matter = 10 (1- S/B) * 0.67 * (1/W)
Where:S = ml sample titration
B = ml blank titration
W = weight of sample
RESULTS:
Calculated
Soil 1 weight (g) mL beginning mL end mL used % OM____
Calculated
Soil 2 weight (g) mL beginning mL end mL used % OM
Notes
Procedure:
1) Weigh 0.2g of soil that has passed through a 2mm sieve into a 250 ml
Erlenmeyer flask.
2) Using a volumetric pipette, add 10ml of 1N K2Cr2O7 and swirl the flask gently
to disperse the soil in the solution.
3) Under hood, add 10 ml of concentrated H2SO4.
4) Immediately swirl the flask gently until soil and reagents are mixed, then stir
vigorously for a total of 1 minute.
5) Allow standing for 30 minutes.
6) Add 100 ml of distilled water to the flask.
7) Add 4 drops of O-Phenanthroline indicator.
8) Titrate with 0.5 N FeSO4. The titration will go from orange to green to bluish
before the endpoint. The endpoint will change from blue to red, a maroon or
coffee color.
9) Make a blank determination in the same manner, but without soil to standardize
the potassium dichromate.
10) Repeat Steps 1-9 using (different soil or compost).
EXERCISE 1. The Walkley-Black Method
Equipment: 1 N K2Cr2O7
Concentrated H2SO4
0.5 N FeSO4  7H2O
0.025 M o-phenanthroline -ferrous complex indicator
Burettes
250 mL Erhlenmeyer flasks
Balance
Pipettes
Magnetic stir plate
Graduated cylinder
Reagents:
Potassium Dichromate - 1N. Dissolve 49.04g of the reagent grade K2Cr2O7 (dried at
105C) in distilled water and dilute the solution to a volume of 1000ml.
O-Phenanthroline – Ferrous complex, 0.025 M – Dissolve 14.85g of O-Phenanthroline
monohydrate and 6.95g FeSo4. 7H2O in distilled water and dilute the solution to a volume
of 1000ml.
Ferrous Sulfate, 0.5N – Dissolve 140g of reagent grade FeSO4.7H2O in water, add 15 ml
conc. Sulfuric acid. Cool the solution and dilute it to a volume of 1000ml.

24. AL 380 - PRINCIPLES OF SOIL SCIENCE
Fall Semester 2018
Instructor: M.H. Golabi, PhD
Laboratory Exercise No. 5
SOIL TEXTURE ANALYSIS
Results:
Soil Time Hydrometer (g/L) Temp (F) %Sand %Silt %Clay
Akina 40 sec
2 hr
Guam 40 sec
2 hr
Blank 40 sec
2 hr
Calculations:
%silt + clay = ((Ts - 67) * 0.2 + (Hs - Hb)) x 1 L x 1/50 g soil x 100
(first reading)
%clay = ((Ts - 67) * 0.2 + (Hs - Hb)) x 1 L x 1/50 g soil x 100
(second reading)
%silt = %silt + clay - %clay
%sand = 100% - %silt+clay
Where: Ts = temperature of sample (F) (to convert C to F: F = (C + 17.98) x 1.8)
Hs = hydrometer reading of sample (g/L)
Hb = hydrometer reading of blank (g/L)
Use the attached textural triangle and determine the textural class of each of the two soils.
Akina _________________
Guam _________________
Notes:
Themethodmostcommonlyusedfordeterminingsoiltextureusesthefactthat
therateatwhichsoilparticlessettleinsolutionisdeterminedprimarilybythesizeofthe
particle. Largeparticles settlefasterthansmaller particlesbecausesmaller particles
presentmorespecificsurface area. Theequationtocalculatethesettlingvelocityis
knownasStoke’s Law. Thisequationcouldbeexpressedas:
v=kd2
Where:
v=settlingvelocity(cm/sec)
k =constant(approx.10,000)
d=particlediameter(cm)
Therefore, asandparticle,whichhasamaximumdiameterof0.005 cm,hasthefollowing
settlingvelocity:
v=10,000X(0.005)2
= 0.25cm/sec
Forasandparticletosettle10cm:
Time(sec) =distance/velocity=10cm/0.25cmpersec=40sec
Exercise 1. Determining soil texture
Equipment: 1 L glass cylinders
milk shake mixer
Sodium hexametaphosphate (50 g/L)
Plunger
Balance
Bouyoucos hydrometer
Thermometer
Procedure Comments
1. Weigh 50 g of Akina and Blender will help disperse
50 g of Guam soil and the soil mechanically.
transfer to a blender container.
2. Add 20 ml of sodium hexametaphosphate Sodium hexametaphosphate
(dispersing agent) and 500 ml of distilled disperses the soil chemically.
water.
3. Blend for 15 minutes using the blender.
4. Transfer to a 1 L cylinder and fill cylinder
to the 1 L mark with distilled water.
5. Mix thoroughly with a plunger.
6. Place hydrometer into the solution and take This reading measures the
the first reading after 40 sec. Also take amount of silt and clay in
a temperature reading. suspension.
7. Let the solution in the cylinder stand and take a This reading measures the
second reading for the hydrometer and amount of clay in suspension.
temperature after 2 hours.
8. Make a blank determination with 20 mL of This reading corrects for the
the sodium hexametaphosphate and distilled increased density of the water
water and mix with plunger. Take the due to the addition of the
hydrometer reading as described in steps 6 &7. sodium hexametaphosphate.

25. GLOSOLAN
Collaboration
and
Expectations ?:

26. ARE THEY MOBILE LABORATORIES?
No
ARE SOIL KITS COMMONLY USED?
Sometimes in the field
Soil Analysis in your country:

27. WHAT DO YOU THINK YOUR LAB IS STRONG AT?
As was indicated earlier the soil labs not only support
the UOG researches who are working in the field.
Also supports undergraduate, graduate as well as
local school students.
WHAT DO YOU THINK IT COULD IMPROVE IN
YOUR LAB?
Our major challenge at the soil labs in Guam is the
equipment maintenance and equipment update.
Strength and Weakness of your lab:

28. Among the problems that we have in Guam is access
to technical personal for equipment maintenance.
Is there a way to establish equipment maintenance
cooperation with the ASPAC?
Same questions applies to parts and supplies for the
replacement
Another question is that, if there is a way to establish
a sample analysis being performed at the ASPAC in
case of equipment malfunction in our lab?
Also, would it be possible that the ASPAC could
provide training opportunities for lab technicians and
students from our labs/graduate programs.
EXPECTATIONS FROM THE MEETINGS:?

29. Source ?

30. Courtesy of: Dr. Bob Gavenda, NRCS