This document describes a field study on soil sampling techniques and measuring bulk density. It discusses taking both disturbed and undisturbed soil samples using various tools. Bulk density, porosity, and soil water content were calculated using sample mass and volume measurements. The bulk density was found to be 1.2 g/cm3, porosity was 55%, and water-filled porosity was 68%, indicating a fine-textured soil. Proper soil sampling and analysis of physical properties provides valuable information for agriculture and construction.

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BAHIR DAR UNIVERSITY
COLLEGE OF AGRICULTURE AND ENVIRONMENTAL
SCIENCE
Graduate Program in Agronomy(MSc.)
Field Report for the Course of Advanced Soil Science
Practical on Soil sampling, sampling types and Measuring of Bulk
Density
BY
Getalew Ayizengaw (ID, BDRU1018259PR)
Submitted to; - Field Assistant
Solomon Afework (Msc.)
December, 2017
Bahir Dar, Ethiopia

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Table of Contents
LIST OF TABLES....................................................................................................................................... iii
1. INTRODUCTION ....................................................................................................................................1
1.1 OBJECTIVES OF FILED WORK .....................................................................................................2
2. MATERIAL AND METHODS................................................................................................................3
2.2 MATERIALS AND METHODS USED FOR DISTURBED AND UNDISTURBED SOIL
SAMPLING..............................................................................................................................................3
2.21 Materials used for Disturbed soil samples ....................................................................................3
2.22 Techniques used to take Disturbed soil samples...........................................................................3
2.23 Materials used for Undisturbed soil samples ................................................................................4
2.24 Methods used to take Undisturbed samples for Bulk Density Measurements..............................4
3. RESULT AND DISCUSION ...................................................................................................................5
3.1 BULK DENSITY................................................................................................................................5
3.2 SOIL POROSITY (Ø).........................................................................................................................7
3.3 SOIL WATER ....................................................................................................................................8
4. CONCLUSION AND RECOMMENDATION ................................................................................................11
5. REFERENCE.............................................................................................................................................12

3. iii
LIST OF TABLES
Table 1 shows that the laboratory result data of the mass of sample before and after dry and soil
moisture contents. ........................................................................................................................... 5
Table 2 summary of the soil properties determined for our sample ............................................... 9

4. 1
1. INTRODUCTION
Soil testing in Agriculture has become an important tool for assessing soil fertility and arriving at
proper fertilizer recommendations, and also its significant in construction sectors for engineers as
A pre- request before they are going to installing buildings and other projects in specific areas. It's
also a valuable management aid for studying soil changes resulting from cropping practices and
for diagnosing specific cropping problems. Soil sampling technique, timing of sampling and type
of analysis need to be considered for accurate results. The biggest problem in the effective use of
soil testing is proper and representative sampling. Proper soil sampling will provide accurate soil
test results and reliable nutrient recommendations. Soil variability is a major concern when
deciding how to collect a representative soil sample. Soil samples submitted for analysis should
be representative of the field or portion of a field. Therefore, by sampling from an area of the field
where it represents typically on average, soil test results should come back with an average
representation of the field. Identifying areas that are representative can be difficult without a first-
hand knowledge of the field. If the person taking the soil samples does not take the time or have
the knowledge required to take a sample in the appropriate location, the results can come back
somewhat unrepresentative (Tracy Barhart,2011).
In our field work in collaboration with department field Assistants, and which is organized by
Bahir Dar University college of Agriculture and Environmental science, soil science department
we had practiced in the department field site on how representative soil sample is taken, types of
sampling techniques, and samples, necessary equipment’s to take each sampling, and how we
measure Bulk Density using sample soils.

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1.1 OBJECTIVES OF FILED WORK
The major objectives of these field work will be to have Practical knowledge on how, when, where
and to which purpose representative soil sample will be taken.
Furthermore, specifically, its objective will be to know both the disturbed and un disturbed soil
sampling and purposes of both types of soil sampling techniques, to be familiarize with sampling
materials and how and when did sampled soil will be going to laboratories for further works, how
soil physical parameter specifically how Bulk density is measured.

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2. MATERIAL AND METHODS
2.2 MATERIALS AND METHODS USED FOR DISTURBED AND
UNDISTURBED SOIL SAMPLING
2.21 Materials used for Disturbed soil samples
The following materials are used in our practical field works to take disturbed soil samplings;
 Auger
 Shovel
 Pestle and mortar
 Hoe
 Rope
 Meter
 “Chekale” etc.
2.22 Techniques used to take Disturbed soil samples
The structure of the soil is disturbed to the considerable degree by the action of the sampling
tools or the excavation materials (Tracy Barhart,2011).
Among the various soil sampling techniques like zig zag methods, diagonal method, S-shape
methods, star methods and Grid methods etc. For our practical works fortunately, we prefer to use
the diagonal methods in our field work to take disturbed soil samples. However, before we are
going to take soil samples we just observe the topographic nature and stratified of our field, i.e.
the pre-request to choose our sample taking techniques (diagonal methods), and sample size. Then
using “chekale” and rope we just prepared our field design and bisect our field in equal dimension
diagonally, here after we took a total of 9 Representative samples in that field where as 5 samples
in one dimension and rest 4 samples from the adjacent areas or we take one sample in the center
and 2 samples in each 4 dimensions within a uniform distance in depth of 20cm using Auger (the
sampling depth depends on our study purposes and nature of the crops) and then after we took the
samples to take 1 kg of the representative amount of sampled soil we are going to bulk (mix) and
divide in to 4 and discard one of each side repeatedly and mix and again divided in to 4 part until
we get the desired amount of sampled weight( 1kg). After that using pestle and mortar we tried to

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mill it and prolapse the grinded soil in the sieve which have 2mm hole diameter and discarded the
which cannot pass through in that diameter sieves because we cannot consider it as soil. After we
took our sample with proper sampling techniques and with proper labeling in these ways we are
going dray the sample in drying room with air drying to avoid sun drying and minimize volatility
of soil nutrients for further analysis.
2.23 Materials used for Undisturbed soil samples
While we took the sample soil without disturbing and keeping the structural integrity of the soil,
we were used materials to take sample like;
 Hoe
 Core sampler (5cm*5cm diameters)
 Scrapers
 Plastic hammer (malleus hammer)
2.24 Methods used to take Undisturbed samples for Bulk Density
Measurements
Undisturbed soil samples retain the structural integrity of the in-situ soil and have a high recovery
rate within the sampler. Collecting a perfectly undisturbed sample is difficult and the samplers
may contain a small portion of undisturbed soil at the top and bottom of the sample length (Tracy
Barhart,2011).
Using hoe we dig and tried to remove the top soil and debris on the surface of the soil and after
that we put on the core sampler on one side of the wall (profile) of soil and hit the core sampler
using malleus hammer until it get in to deep, and it took enough volume of sample , after we are
certain that our core sampler get in deep and filled with soil , using crowbar we uplift and remove
the edge part of the sample with maximum care and using Scrapers properly flapping the core
sampler and we took and measure it in the laboratory for Bulk density analysis, which is one of
the most important soil physical properties and vital for further explanation and measurement
might be taken using representative sample for farmers and engineers. But when I come with the
points, using sensitive balance we weight our sample soil before dry and it measures 158.1 gram,
and after it dried using oven dry with 105o
c for 24 hrs. it measures 120.5grams

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3. RESULT AND DISCUSION
3.1 BULK DENSITY
Bulk density is the mass of a given volume of dry soil in its natural condition (the mass of the
solids and the pore space). It is determined by removing a block of soil from site, allowing no
compaction or crumbling. This is often done by hammering a can or metal ring (in our field work
we use core sampler) into the soil and digging the ring or can out when full of soil. The soil is
then dried in an oven and weighed.
The volume is determined by measuring the volume of the container used to extract the soil. The
bulk density is expressed in unit’s grams of oven-dry soil per cubic centimeter (Blake & Hartge,
1986):
Bulk Density = oven-dry soil (g) / soil (cm3)
Bulk densities of soils range from about 1.0 g/cm3 (fine-textured soils) to 1.4 or 1.7 g/cm3
(coarse-textured soils). Tillage that loosens soil can temporarily decrease bulk density, while
compaction will increase it (Brady & Weil, 1996).
Table 1 shows that the laboratory result data of the mass of sample before and after dry and soil moisture contents.
No Parameters Mass of parameters
in (kg)
1 Mass of wet soil 158.1
2 Mass of dry soil 120.5

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Bulk density (Pb) in g/cm3
= mass of dry soil (g)/volume of soil sample (cm3)
Whereas the total volume (cm3
) will be calculated using a formula of
Volume (cm3
) = height of core sampler (cm) * Area of the core sampler ∏r2
= 5cm*3.14(2.5 cm)2
=98.125 cm3
Whereas the bulk density will be calculated using the above formula
Bulk density (Pb) g/cm3
= Mass of Dry sample in g/ Total volume of sample (cm3
)
Pb (gm/cm3
) = 120.5g/98.125cm3
= 1.2g/cm3
As expressed in the above when the soil has a bulk Density in Ranges from 1.0 g/cm3
-1.4 g/cm3
the soil side to be a fine texture soil, therefore our result is in between ranges and our soil were
affine texture soil and the textural class our sampled soil will be silt-loam.

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3.2 SOIL POROSITY (Ø)
Porosity is a value that expresses the relative amount of pore space in the soil. It is not measured
directly but is calculated from the bulk density and particle density (Brady & Weil, 1996):
Porosity = 1 - (bulk density / particle density)
Particle density is the density of just the solid part of the soil, it does not include any pore space.
Particle density varies according to the mineral content of the soil particles. It does not usually
vary a lot in most soils. In most soils the particle density is about 2.65 g/cm3; the density of
quartz is 2.65 g/cm3 and quartz is the dominant mineral in most soils (Brady & Weil, 1996).
Porosity(ø) = 100- bulk density/particle density*100%
= 1-pb/pp) *100%
Bulk density(Pb)=1.2g/cm3
Particle density will be 2.65g/cm3
Porosity(ø)=1-1.2/2.65) *100%
= 55%
The pore space of a soil is the space occupied by air and water. The amount or ratio of pore space
in a soil is determined by the arrangement of soil particles like sand, silt and clay. In sandy soils,
the particles are arranged closely and the pore space is low. In clay soils, the particles are arranged
in aggregates and the pore space is high. Presence of organic matter increases the pore space. On
the basis of porosity, the soil texture will be; Sandy surface soil: 35 to 50 %, Medium to fine
textured soils: 50 to 60 %, Compact sub soils: 25 to 30%, and on the basis of our results of porosity
(55%) the textural class will be the same as fine texture soil as we did in the bulk density range
classifications, and the ideal soil porosity for good crop production will be in ranges 30-60%.

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3.3 SOIL WATER
The amount of water in a soil available for plant use is one of the most important measurements
needed for proper plant growth in over all crop production and irrigation management. While the
porosity of most agricultural soils is in similar ranges, the amount of plant-available water varies
greatly. This is due to size of the pore space in a soil and the way water is held within the pores
of a soil. We can calculate the percentages of total pore space occupied by water and soil. To
calculate water filled porosity, the volumetric water content, or percentage water by volume must
be determined. volumetric water content is determined by finding the percentage water content
by weight in the sample, then multiplying the water content of the sample by its bulk density.
soil water content is determined as follow;
Water content (Ꝋg)= wet soil mass (g) - dry soil mass (g) *100
Dry soil mass(g)
= 158.1(g)-120.5(g) *100
120.5(g)
= 0.312 g H2O /g Soil (31.2% by mass)
Soil water content is the mass of water per unit mass of solid particle, For the sample above each
gram of soil contains 0.312 g of water. Where as the subscript “g” stands for” gravimetric
“which means that the water content in the sample was determined by mass difference (in this
case, loss of water mass during oven drying).
Volumetric water content (Ꝋv) = water content (Ꝋg)*Bulk density/water density
= 0.312g/1g*1.2gcm-3
/1gcm-
3
= 0.374cm3
water / cm3
dry soil (37.4% by volume)
Water filled porosity is determined by;
water filled porosity (øw) =% water by volume/total porosity(Ꝋ) *100
= 37.4%/55% ×100

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= 68%
Table 2 summary of the soil properties determined for our sample
Property Value
Particle density 2.65gcm-
3
Bulk density 1.2gcm-
3
Total porosity 55%
Water filled
porosity
68%
Gravimetric
water content
0.312g
Volumetric water
content
0.374g
The above result shows that the particle density of 2.65g/cm3 indicated that the sample is a mineral
soil with relatively low organic matter content, even if the percentage of sand silt and clay is not
clearly known the particle density suggests that the sample is affine texture soil. As shown from
table 2, a soil with a bulk density of 1.2g/cm3 and 55% total porosity also suggests that along with
particle density, the soil is fine textured soil. the total porosity includes micro and macro pores, as
such, it tells us nothing about the distribution of pore size in the soil. Water is held less than about
0.05mm in diameter by cohesive force and adhesive forces and collectively called capillary forces,
and which is the main reservoir of plant available water and determine the soil water holding
capacity. In contrast with water drains with gravitational force from macro pores with a diameter
larger than 0.05mm. if we assume the soil was at field capacity when the sample was taken i.e all
gravitational water having drained away from the sample zone, the volume of water filled pore
space should roughly equal to the volume of capillary pore space. the calculated water filled pore
space in our sample was 68%, in turn the percentage by volume of air filled pore space can be
found by subtracting 100-68= 32%.
The ideal agricultural soil will be filled with equal volume of the total pore space. However, the
relative amount of water and air-filled pore space fluctuates constantly. Rain fall infiltrating the
soil drives air out of the pores, but as the soil dries, air reenters and pores gradually reaching filled

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capacity over period of 1-3 days depends on the soil texture and internal drainage. For growing
plants, the distribution of pore sizes is more important than total porosity.
The depth of water in the soil can also be calculated from the volumetric water contents since 1cm3
of water also occupies a cubic of 1 cm *1cm*1cm (L*W*H) if no soil particles are present. Thus,
soil with a volumetric moisture contents of 0.374cm3 would occupy layer 1cm long 1cm of width
and 0.374cm height. The volumetric water content of 37.4% therefore equal to a depth of 0.374cm
water per centimeter of depth of soil. In our field work our core sampler measured 5cm deep so
the total depth of water in the core is 5×0.374= 1.87cm.

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4. CONCLUSION AND RECOMMENDATION
A soil test can determine Fertility or the expected growth potential of the soil which indicates
nutrient deficiencies, potential toxicities from excessive fertility and inhibitions from the presence
of non-essential Trace elements. The test is used to mimic the function of roots to assimilate
minerals. The expected rate of growth is modeled by the Law of maximum (Malcom E. and
Sumner,2012). Therefore, we should take a representative soil sample for further soil testing.
While we take Sample Soil samples should always be taken in a consistent manner. In particular,
make sure each sample is the same size, and that each core or slice is uniform from the soil surface
down to the sampling depth. A soil tube makes consistent sampling easier, but you still can also
take good samples with a spade or trowel, though it will require a bit more care during sampling.
In general soil samples are categorized as Disturbed and un disturbed samples, each sampling has
its own merits, and techniques of samplings. The bulk density, porosity and soil moisture contents
Are the most important soil physical properties and our sample having a bulk density of 1.2g/cm3
which is a normal range, A porosity of 55% and 68% a pore filled with water it shows more water
are held in pores and maybe while we take a sample we took a sample from comparatively moist
areas but it will come in to filed capacity days after. How ever our sample soil has comparatively
a fine texture and has more or less good structure of Agriculture with continuous managements to
enrich soil nutrients and attaining good yield.

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5. REFERENCE
Blake, G.R., and K.H. Hartge. 1986. Bulk density. p. 363-375. In A. Klute (ed.) Methods of soil
analysis. Part 1. (2nd ed.). Agron. Monogr. 9. ASA and SSSA, Madison, WI.
Brady, N.C. and R.R. Weil. 1996. The nature and properties of soils (11th ed.). Prentice Hall,
New York.
Malcom E. and Sumner,2012. Soil science google book. Retrieved from
http://www.books.google.com. on December22,2017
Tracy Barhart,2011, july 17. Disturbed and undisturbed soil sampling. Retrieved from
http://www.hunker.com on December22, 2017.

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