1. Proper collection and preparation of soil samples is extremely important for meaningful soil test results and accurate fertilizer recommendations. A representative soil sample is obtained by collecting 10-20 subsamples from different areas of a field and mixing them together. 2. Soil samples should be air dried, crushed, and sieved to 2mm before storing and analyzing to determine fertilizer needs and application rates through soil testing. 3. Many factors including slope, texture, drainage, and crop history must be considered when delineating sampling areas and collecting subsamples to ensure a representative composite sample.

1. Soil Laboratory No. 1
Collection and Preparation of Soil Samples
I. Introduction
To ensure efficient crop production, soils must have an adequate supply of plant nutrients.
Where no soil can sustain high yields if it is deficient in nutrients, an evaluation or inventory of its
nutrient supply is essential. Not only must nutrient elements be present in the forms that plants can
take from the soil, but they should be present in proper amounts and in the proper balance in
accordance with the amount needed for the growth of the specified plants. Thus, if any of those
nutrient elements are lacking in the soil, itshould be supplied in the soil in the form of fertilizers. The
kind and amount of fertilizers to be applied to the soil can be determined through soil testing. Soil
testing is primarily a fertility management tool that has value because it helps predict fertilizer needs
and in predicting fertilizer application rates.
Soil sampling is an integral part of soil testing. Since the accuracy of nutrient recommendation
depends to a large degree on the collection and preparation of soil samples, proper collection and
preparation of soil samples intended for analysis are extremely important. a representative soil
sample is a prerequisite for a meaningful analytical result and an accurate fertilizer recommendation.
Therefore, taking a representative soil sample is both the first step and the largest source of error in
the soil fertility evaluation program.
This exercise discusses the prescribed guidelines or procedures in the collection and
preparation of a representative soil sample.
II. Objectives:
At the end of this exercise the student should be able to:
1. Explain the importance of soil testing in crop production.
2. Discuss the basic concepts in the collection and preparation of soil samples for analysis.
III. Materials
1. Soil Auger 4. Bolo
2. 2 pcs of manila paper 5. Pentel Pen
3. 2 pcs plastic bags (about 2 kg capacity) 6. 2 wide-mouth plastic jars with
Cover

2. IV. Procedure
a) Collection of Soil Samples
i. Inspect the farm and take note of its land features such as topography or slope,
texture, drainage condition, and crop raised.
ii. If the area varies in any or all of the characteristics above then, divide the area into
homogeneous lots and each lotshould be sampled separately. A farm seldom has
uniform land features. It may have level as well as sloping portions. Collect a
sample that represents an area uniform in slope, texture, drainage, and crop
raising.
iii. From each lot, collect 10-20 subsamples that will be mixed thoroughly to form a
“composite soil sample”. In collecting a composite soil sample, each of the lots on
the farm should be represented. A composite soil sample is obtained following the
step below:
1. Scrape away grass or plan residues from the surface of the soil to be
sampled.
2. Get a sample ofthe soil with the use of a soil auger to a depth of 15-20cm
and place itin a pail or sampling bag. Ifa soil auger is not available, dig a
V-shaped hole with the use of a bolo or shovel and discard enough soil so
that a clean side about 15-20 cm deep is exposed.
3. Remove from the smooth side a thin slice of soil about 3cm thick and
about 15-20cm deep.
4. Trim the sides of the soil slice, leaving about a 3 cm or 1-inch strip in the
middle.
5. Discard the sides of the soil slice and place the 1-inch middle strip in the
sampling bag. When deep-rooted crops are or will be planted, composite
subsoil should be collected. To collect this sample, the pit left after
collecting the surface soil sample is continued to the desired depth usually
between 60 cm to 90 cm as the subsoil sample, and placed in a separate
sampling bag.
6. Repeat steps (1) to (5) until 10-20 subsamples are taken. These samples
should be taken at random at equally distant points throughout the lot in a
zigzag direction.
7. Mix all soil collected from 10-2- points ofthe sampling lotin a clean plastic
sheet and divide it into four quadrants. Discard the two quadrats and
retain the other 2. Repeat the process until the remaining sample is only
one kilogram.
8. Place the composite surface and subsoil samples in a plastic bag
separately. Attach to the sample a soil information sheet as:
a. Farmer’s name and address
b. Location of the farm

3. c. Area of farm
d. Surface or subsoil sample
e. Date collected
f. Crops are grown or to be grown
g. Yield record of past crop
h. Past treatment like fertilization, liming, etc.
i. Length of time the land was cultivated for a particular crop
j. Slope condition and other physical features of the lot
b) Preparation of soil samples
i. Separate the sample on a drying board in a soil preparation room. Crush the clods
occasionally during the drying process. It takes about a week for soil to dry.
ii. After a week when the soil is already dried, pulverize the soil using a wooden
malle and let it pass through a 2-mm sieve. Discard the particles that do not pass
through the sieve. All stony materials (gravel, rock fragments, and other special
features) should be picked out.
iii. Store the sample in a plastic bag or jar with the appropriate labels. This sample is
ready for analysis.
V. Reference:
BRADY, N.C. and R.R. WEIL. 2001. The Nature and Properties of Soils. 13th ed. Prentice-Hall
Inc., New Jersey.
PCAARRD. 1980. Standard Methods of Analysis for Soil, Plant Tissue, Water and Fertilizers.
Laguna, Philippines.
DAQUIADO N. and CAGMAT R., 2018. Introduction to Soil Science Laboratory Manual.
Central Mindanao University, University Town, Musuan, 8710 Bukidnon.

4. Exercise No. 1: COLLECTION AND PREPARATION OF SOIL SAMPLES
Name:_____________________________________________Score:__________________________
Section:____________________________________________Date Performed:__________________
1. Make a sketch ofthe area from where you took your soil samples and indicate the sampling points.
2. Fill out the information needed in the label of the soil samples you have collected.
a. Farmer’s name and address: ____________________________________________________
b. Location of the farm:___________________________________________________________
c. Area of farm:_________________________________________________________________
d. Surface or subsoil sample:______________________________________________________
e. Date collected:_______________________________________________________________
f. Crops grown or to be grown:____________________________________________________
g. Yield record of past crop:_______________________________________________________
h. Past treatment like fertilization, liming, etc.:_________________________________________
___________________________________________________________________________
i. Length of time the land was cultivated for a particular crop:_____________________________
___________________________________________________________________________
j. Slope condition and other physical features of the lot:_________________________________
___________________________________________________________________________

5. 3. Give at least three characteristics of a representative soil sample.
a.
b.
c.
4. Enumerate at least five precautions in the collection and preparation of soil samples.
a. ________________________________________________________________________
________________________________________________________________________
b. ________________________________________________________________________
________________________________________________________________________
c. ________________________________________________________________________
________________________________________________________________________
d. ________________________________________________________________________
________________________________________________________________________
e. ________________________________________________________________________
________________________________________________________________________
5. Attach the documentation of step-by-step procedures of collecting soil samples.