GROUP MEMBER:

NAME IC

LIM JIA HUI 960530-01-7060

RIRI ANDRI ANI BINTI MUSTAFA TAN 961114-01-6864

KAW SHIM YEE 960123-08-5154

DEDICATION

MAKTAB SULTAN ABU BAKAR, JOHOR BAHRU.

pH of Soil Solution in Water and KCl Solution

We are heartily thankful and grateful to our teacher, Mr Mohamad Rashidi Bin

Anang who gave us encouragement, guidance and support from the initial to the final

steps of the research and had successfully enabled us to develop an understanding of

the research. Special thanks to our group members for their dedication and hard work

towards this research.

Lastly, we offer our regards and blessings to all of those who supported us in

any respect during the completion of the project.

ABSTRACT

Soil is the mixture of minerals, organic matter, gases, liquids, and the

countless organisms that together support life on earth. The acidity or alkalinity of soil

is important for plant growth and is expressed on a pH scale, based on the total

hydrogen ion concentration in the soil water solution. In order to test the soil pH, we

use pH meter to determine as it is the most accurate method. A pH Meter is an

electronic device used for measuring the pH which is either the concentration of

Hydrogen ions in an aqueous solution or the activity of the hydrogen ions in an

aqueous solution. As the function of pH meter is needed in aqueous, the soil sample

need to be in the aqueous or solution form. The pH will indicate if the solution is

acidic or basic. On this scale, neutral condition is represented by a pH of 7, values 7 to

0 are increasingly acidic and 7 to 14 are increasingly alkaline. For very precise work

the pH meter should be calibrated before each measurement. Calibration should be

performed with at least two standard buffer solutions that span the range of pH values

to be measured. For general purposes buffers at pH 4.01 and pH 10.00 are acceptable.

CHAPTER 1: INTRODUCTION TO TITLE

1.1 INTRODUCTION

Soil pH is a measurement or an indication of the acidity or alkalinity of a soil. Soil

pH is defined as the negative logarithm of the hydrogen ion concentration. On the pH

scale, 7.0 is neutral. Below 7.0 is acid, and above 7.0 is basic or alkaline. A pH range

of 6.8 to 7.2 is termed near neutral. As the amount of hydrogen ions in the soil

increases the soil pH decreases thus becoming more acidic. From pH 7 to 0 the soil is

increasingly more acidic and from pH 7 to 14 the soil is increasingly more alkaline or

basic.

Soil pH is considered a master variable in soils as it controls many chemical

processes that take place. It specifically affects plant nutrients availability by

controlling the chemical forms of the nutrient. The optimum pH range for most plants

is between 5.5 and 7.0, however many plants have adapted to thrive at pH values

outside this range. Soil pH provides various clues about soil properties and is easily

determined. The most accurate method of determining soil pH is by a pH meter. A

second method which is simple and easy but less accurate then using a pH meter,

consists of using certain indicators or dyes.

1.2 LITERATURE REVIEW

A report (Alley & Zelazny, 1987) from the USA stated that lime

recommendations by soil testing laboratories are inaccurate, also resulting in lime

application where none is needed. Such recommendations, often based on a critical

pH concept regarding yields can result in lost farm income, increased input costs and

loss of credibility by soil test laboratories.

Sikora Buffer Method

An experiment was conducted by Sikora, F. J. in year 2006. This soil science

project is used Sikora Buffer Method to determine the pH in soil and minimise the

SMP buffer. It is well know that, SMP buffer contains two hazardous chemicals

(paranitrophenol and chromium). Due to this, he used a 1:1 soil: solution ratio and in

a buffer solution with a 1:1:1 soil: water: buffer ratio. He used the pH meter with

combination reference-glass electrode .However, for those soils with a pH below the

level that is considered acceptable for acid-sensitive crops, a Sikora buffer solution

with a pH of 7.70 ± 0.01 is added and the Sikora-pH is measured. Depression of

buffer pH by the soil gives an indication of the soil’s pH buffering capacity. Thus, the

pH of the soil was obtained

Woodruff Buffer

Brown, J.R and J.R Cisco has construct an experiment that make used of

Woodruff Buffer to estimation of pH of soil in year 1984 . He dissolved calcium

acetate (Ca (C2H3O2)2) and calcium hydroxide (Ca(OH)2) in 500 mL cool distilled

water and heat until 70 degree and dissolved paranitrophenol in the hot water.

Salicylic acid (C7H6O3) also be used in his experiment .To prevent interpretation , he

stored the buffer solution in the container protected from air .In this method , he also

mentioned that the air -dry -soil must be stored in closed container for several months

with no effect on pH. Thus, the pH of the soil will be calculated accurately.

1.3 PROBLEM STATEMENT

In order to study the pH of soil solution in water and KCl, various types of soils

such as swamp soil, river bank soil and farm soil were used and measured by pH

meter which is an electronic device used for measuring the pH which is either the

concentration of Hydrogen ions in an aqueous solution or the activity of the Hydrogen

ions in an aqueous solution. The pH will indicate if the solution is acidic or basic.

1.4 OBJECTIVES OF RESEARCH

It is hoped that throughout the research, we are able to

Determine the pH of various types of soil solution in water and KCl.

Analyse the effect of pH of soil on availability of nutrients and the plants

growth.

1.5 SCOPE OF RESEARCH

We will collect the swamp soil, river bank soil and farm soil from Taman

Tampoi Utama, Taman Pulai Perdana and Taman Tampoi Indah

respectively and determine their pH by using pH meter.

CHAPTER 2: METHODOLOGY

2.1 LIST OF APPARATUS AND MATERIALS

In order to successfully conducting the experiment, the following apparatus

and materials are used. Apparatus and materials used are as follow: pH meter,

standard flasks, magnetic stirrer, filter funnel, beaker, wash bottle, tissue paper,

forceps, potassium chloride and distilled water.

2.2 PROCEDURE

2.2.1 PREPARATION OF BUFFER SOLUTIONS

1. Buffer Solution of pH 4.0

Dissolve 5.4g of sodium acetate in 50 ml of water, add 2.4 ml of glacial

acetic acid and dilute with water to 100ml.

2. Buffer Solution of pH 10.0

Dissolve 5.4g of ammonium chloride in 20ml of water.

Add 35ml of 10M ammonia and dilute with water to 100ml.

2.2.2 CALIBRATING THE INSTRUMENT

Step 1

o In a 100 ml beaker take pH 10.0 buffer solution and place it

in a magnetic stirrer, insert the teflon coated stirring bar and stir

well.

o Now place the electrode in the beaker containing the stirred

buffer and check for the reading in the pH meter.

o If the instrument is not showing pH value of 10.0, using the

calibration knob adjust the reading to 10.0.

o Take the electrode from the buffer, wash it with distilled water

and then wipe gently with soft tissue.

Step 2

o In a 100 mL beaker take pH 7.0 buffer solution and place it

in a magnetic stirrer, insert the teflon coated stirring bar and stir

well.

o Now place the electrode in the beaker containing the stirred

buffer and check for the reading in the pH meter.

o If the instrument is not showing pH value of 7.0, using the

calibration knob adjust the reading to 7.0.

o Take the electrode from the buffer, wash it with distilled water

and then wipe gently with soft tissue.

Step 3

o In a 100 ml beaker take pH 4.0 buffer solution and place it in

a magnetic stirrer, insert the teflon coated stirring bar and stir

well.

o Now place the electrode in the beaker containing the stirred

buffer and check for the reading in the pH meter.

o If the instrument is not showing pH value of 4.0, using the

calibration knob adjust the reading to 4.0.

o Take the electrode from the buffer, wash it with distilled water

and then wipe gently with soft tissue.

o Now the instrument is calibrated.

2.2.3 TESTING OF SAMPLES

1. Measure a volume of soil from 10 to 20 ml, or mass of soil from 10 to

20 g, and add it to a sample cup. Volume is measured with a soil sampling

scoop. Mass can be measured with a scale or estimated from a volume

measurement accounting for the density of soil.

2. The next step considers different variations on the type of solution

added to soil.

a) 1:1 soil:water pH: Dispense a particular volume of water to soil

that is equal to the volume or mass of soil.

b) 1:1 soil:1 M KCl pH: Dispense a particular volume of 1 M KCl to

soil that is equal to the volume or mass of soil.

3. Stir the soil and solution vigorously and allow slurry to set from 15

minutes to 1 hour.

4. Ensure room temperature is between 20C and 25C before proceeding

with pH measurement.

5. Calibrate pH meter and electrode using pH 4, pH 7 and pH10 buffers.

6. Place electrode in the soil slurry to measure pH. Measurement may be

taken with or without continuous stirring. If measurement is made without

continuous stirring, stir the sample with a stir bar before placing electrode

in the sample. Allow adequate time for pH to reach a stable reading.

2.3 DATA COLLECTION

Soil Sample PlacepH in

water

pH in

KCl

Swamp Soil

River Bank Soil

Farm Soil

CHAPTER 3: RESULTS AND DISCUSSION

3.1 OBSERVATION AND RESULTS

Soil Sample PlacepH in

water

pH in

KCl

Swamp SoilTaman Tampoi

Utama7.0 7.2

River Bank SoilTaman Pulai

Perdana7.7 7.9

Farm SoilTaman Tampoi

Indah6.7 6.6

3.2 INTERPRETATION AND DISCUSSIONS

<5.0 5.5 6.0 6.5-7.5 7.5-8.5 >8.5

Strongly

acid

Moderately

acid

Slightly

acidNeutral

Moderately

alkaline

Strongly

alkaline

Soil pH affects nutrient availability by changing the form of the nutrient in the

soil. If the pH of a solution is not within the correct range the plant will not have the

ability to absorb some of the essential elements required for proper plant growth. All

plants have a particular pH range, which will produce healthy growth, and this level

will vary from plant to plant, but most plants prefer a slightly acidic growing

environment (5.8 to 6.2), although most plants can survive in an environment with pH

values between 5.0 and 7.0.

Plants grown in acidic environments can experience a variety of symptoms,

including aluminium (Al), hydrogen (H), and/or manganese (Mn) toxicity, as well as

nutrient deficiencies of calcium (Ca) and magnesium (Mg).

Conversely, in alkaline environments molybdenum (Mo) and macronutrients

(except for phosphorus) availability increases, but phosphorus (P), iron (Fe),

manganese (Mn), zinc (Zn), copper (Cu) and cobalt (Co) levels are reduced, and may

adversely affect plant growth.

From the chart we found that that each element can become more and less

available to the plants as pH changes. If the pH of your solution is out of the desired

range, one or more of the essential elements will become unavailable to the plant,

causing nutrient deficiencies, which will result in slow growth rates, and poor yields.

Based on the results obtained, swamp soil shows the pH of 7.0 and 7.2 in water

and KCl solution respectively. The neutral pH of swamp soil indicates that most of

the macronutrients will be available in swamp soil which is very suitable for swamp

milkweeds and cattails to grow. River bank soil shows the pH of 7.7 and 7.9 which is

moderately alkaline in water and KCl solution. In other words, due to the alkaline pH,

molybdenum (Mo) and macronutrients (except for phosphorus) availability increases,

but phosphorus (P), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu) and cobalt

(Co) levels are reduced. River bank soil is suitable for the growth of duckweed, water

lily and etc. For farm soil, farm soil shows the pH of 6.7 and 6.6 in water and KCl

respectively which fall in the range of neutral which are the most suitable for plant

growth due to the higher availability of nutrients. Farm soil is suitable to grow beans,

avocado and more.

Throughout the experiment, there is some precaution steps needed to be done to

ensure that the results obtained are more accurate. pH measurements can be made to

the nearest 0.1 or 0.01 pH unit. There is no need to measure pH with more than 2

decimal places since this level of accuracy is not achievable or required.

Besides, differences in pH will occur with electrode placed in a soil-slurry or in

the supernatant after the soil has settled. The differences are more pronounced with

soil pH in water compared to electrolyte solutions. To avoid this variability in pH, it

is important to stir the soil slurry right before measurement.

Moreover, glass electrodes have a short life span when measuring pH of sandy

soils. The sand particles are abrasive to the glass resulting in electrode breakage or

malfunction. When electrodes fail to measure pH of calibration buffers or quality

control samples show more error than expected, replace electrodes.

CHAPTER 4: CONCLUSION

Throughout the experiment, we found that the more neutral the pH, the higher the

availability of nutrients. The availability of nutrients is greatly influenced by the pH. So, it is

important for us to analyse the pH before planting so that the plants grow within the correct

range of pH to enhance the absorption of essential nutrients for their growth.

REFERENCE

1. http://chemed.chem.purdue.edu/genchem/lab/equipment/phmeter/use.html ;

research on calibration of pH meter; accessed on 25 June 2015.

2. http://www.novedu.ru/anotes/refer/buffers.htm ; preparation of buffer solution;

accessed on 26 June 2015.

3. http://vlab.amrita.edu/?sub=2&brch=193&sim=1549&cnt=1 ; soil analysis;

determination of soil pH; accessed on 28 June 2015.

4. http://mit.biology.au.dk/~biohbn/Protocol/Soil_pH_20081127.pdf ; research on

soil pH in water and KCl; accessed on 8 July 2015.

5. https://www.google.com/url?

sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&uact=8&ved=0CFw

QFjAJahUKEwjy0qy3mrLHAhVHB44KHaadBCw&url=http%3A%2F

%2Fwww.clemson.edu%2Fsera6%2FSoilpH_Sikora%2520and

%2520Kissel_final%2520Dec%252015.doc&ei=0-

vSVbKdG8eOuASmu5LgAg&usg=AFQjCNH8LZmCVFKvHqsBbGZfbbOK

E91QoQ&sig2=va-HTBidbCXK9HuwtC42vw&bvm=bv.99804247,d.c2E;

research on soil pH experiment, accessed on 15 July 2015.