The document discusses soil sampling methods and procedures for soil analysis. It describes various sampling methods like random sampling, dividing fields into squares or triangles, and zigzag patterns. Samples should be collected from a depth of 0-30 cm for nutrient analysis and 0-200 cm for classification. Composite samples consist of mixing several single samples. Undisturbed samples preserve the soil's natural structure while disturbed samples have been altered. Key steps in sample preparation are drying, grinding, sieving, mixing or partitioning samples, and storing them at 4°C until analysis.

1. Faculty of Science
University of Zakho, UOZ Zakho,
Kurdistan Region – Iraq
Lecturer: Mr. Marwan Basheer
Department of Ecology

2. Soil Sample: Amount of soil taking from the field
represents natural state and most
properties of the soil which take for
analysis.
The aim of taking samples for analysis soil " Chemical,
Physical and biological'' so can be know the fertility of
the soil by analysis.
Soil Sampling
Contd…
Lab. 1: Soil Testing – Collection and Preparation of soil samples.
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3. Objectives of soil analysis:
Determination minerals and organic components of the soil.
Identify origin and classification of the soil.
Determination the effect of environment factors on the soil.
Determination soil fertility.
Determination types and numbers of micro organisms which
living in the soil.
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4. Sampling Methods
1-Randomize method: Use the wood in square field for
collected the samples from different places in the field this
method not represent all the field because of some areas not
survey and some samples may be taken from border the
field.
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5. 2- Dividing the field to squares'' or equal length and width
distances (dimensions)'' then taking the samples from
contribution point of length and width'' intersection point'' so
can be taking the sample from the center of each square in this
method avoid taking the sample from border the field.
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6. 3- Dividing the field to triangles: Dividing the field to
squares then dividing these squares by slope lines on
condition slope lines passing through the intersection point
of width and length lines [vertical and horizontal lines] of
squares after that take the samples on the slope lines with
equal distances , avoid taking the samples from border the
field.
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7. 4-Dividing the field by two diametrical lines on
condition each diameter cut others in intersection
(contribution) point, then take the samples on each
diameter with equal distances, avoid taking the
samples from border the field.
Contd…
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8. 5- Drawing the zigzag lines, then collected the
samples from these lines, avoid taking the samples
from border of the field. It's a good method for
collecting samples, not wanted much effort , rapid
method.
Generally if you taking great numbers of samples in the case
you obtain best and accurate results .
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9. Sampling depth
In general, The depth of sampling depends on
the purpose of soil testing. For example:
 For studying soil genesis, morphology
and classification the soil sample should
be taken from 0 – 2 m depth.
 For testing the availability of nutrients (N, P,
K, ..etc), chemical analysis (pH, EC, O.M) and
fertilizer recommendation usually the soil
sample taken from 0-30 cm because most plant
roots grow to that depth.
A
B
C
30 cm
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10. Time and frequency of sampling
The correct time of sampling cannot be decisively specified.
 Ideally, take the soil samples 3 to 4 weeks
before planting or fertilizing the crop.
For annual crops, especially vegetables, test soil each year before
planting. For perennial crops such as orchards, trees, alfalfa, grass
seed, test soil once every 2-3 years.
 However, soil samples may be taken either in
the fall or spring.
 Early spring is a good time to take soil samples
for summer crops, and summer is a good time to
sample for fall and winter crops.
What season of the year?
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11. Types of samples according to location:
1-Surface samples: samples collected for chemical and biological
analysis, so used for evaluating the fertility
state of the soil usually take from depth (0-30)
cm.
2-Sub-surface samples: samples collected for survey and
classification soils, usually take from
(0-200) cm
Contd…
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12. Types of samples according to Number:
1-single samples: one sample take for analysis.
2-Composite samples: consist of several single or subsurface
samples, then mixed these samples and
take one sample from them, in this case all
single samples must be equal in volume
and weight.
Contd…
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13. Types of samples according to state
2. Disturbed soil sample: is defined as the soil that
its natural status has been destroyed or
disturbed during the sampling process.
1. Undisturbed soil sample: defined as the soil that
collect from the field in a natural state Without
disturbing the natural conditions of a soil
sample.
- Usually used for studying physical properties
of soil (bulk density, structure, permeability).
- Usually used for studying chemical properties
of soil or soil fertility (pH, EC, K, N, P ..etc)
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14. Notes must be followed when collecting the
samples:
Sample volume must be equal of each layer or horizon.
Avoid taking the samples from region which contain disturbed
soil, Wet soil [Irrigated soil], saline regions in the field.
Avoid taking the samples from up to the hill and down to the hill.
Avoid taking the samples near the roads in the field, fertilizer stores.
Samples must be collected at the same time.
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15. Notes must be write on the label of sample
1- project name 2- Name of the person who collect the samples.
3- Location. 4- Date of sampling.
5- Depth of sample. 6- Land use of the field.
7- Number of sample.
* Notes: Two label must be write of each sample
Label pattern for collecting the samples:
project name
Name
Location
Date
Depth
Number of sample
Land use
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16. Equipments of collected the soil samples:
1- Auger. 2- Core or tube. 3- Shovels.
Properties of the Equipments:
1- Small volume (size) and suitable for
taking the sample.
2- Easy cleaning.
3- Rust resistance.
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17. Preparing samples for analyzing:
Preparing process of samples will pass through following steps:-
1- Drying: Air drying.
The samples will spread on a drying tray, or sheet paper, or plastic
(Nylon) sheets, and place in a drying cabinet (room) or on
laboratory until air dry for 18 – 24 hours.
Notice: Samples should be kept away from water, moisture, and
dust or chemical and physical factors that changes its properties.
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18. 2. Grinding and Sieving:
After the soil samples become homogenous break down clods
with a porcelain or a wood hammer, then sieve the soil through a
sieve of (2 mm).
3. Mixing:
In case of single samples will not mixed together, only should be
prepared singly one by one for analyzing, but in case of
composite samples should be mixed single samples in order to
prepare compose sample.
4. Partitioning: by quartering
Spread the sieving soil on a plastic (Nylon) sheet in one direction,
divided it into four squares, take tow square and neglect the
others, and carefully left one sample, then puck it in a plastic box
and label it.
Preparing samples for analyzing
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19. 5. Storage:
The labeled samples should be storage in a laboratory, it's
preferable to store it at 4C because at this degree of temperature,
the activity of more organisms will stopped.
Preparing samples for analyzing:
• pH, EC, K, Mn, Fe, N, O.M. measure at once because of
these properties change when the sample storage.
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20. Thanks for Listening
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