Faculty of Science

University of Zakho, UOZ Zakho,

Kurdistan Region – Iraq

Lecturer: Mr. Marwan Basheer

Department of Ecology

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.

2

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.

Contd…

3

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.

Contd…

4

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.

Contd…

5

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.

Contd…

6

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…

7

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 .

Contd…

8

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

Contd…

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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?

Contd…

10

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…

11

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…

12

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)

Contd…

13

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.

Contd…

14

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

Contd…

15

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.

Contd…

16

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.

Contd…

17

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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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.

Contd…19

Thanks for Listening

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