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- 1 –NATIONAL CERTIFICATE IN ORNAMENTAL

HORTICULUTRE LEVEL 1Workbook : Identifying and preparing soils

for planting

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©Lifestyle College.

Lifestyle CollegeIssue date : January 2005Version 2



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A c k n o w l e d g e m e n t s

Developed by

Lifestyle College

With special thanks to:Tasha Tollman

Rick Smit from Dynamic Solution Synergies




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DESCRIPTION PG NOWorkshop Overview 4The Unit Standard 7Introduction 14Lesson 1 : Soil Layers 17Lesson 2 : Soil Types 31Lesson 3 : Soil Structure and Colour 46Lesson 4 : Soil Enrichments 71Study Session Summary 91References 92


Contents Page



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Purpose

The purpose of this study session is to equip you with the skills necessary to

prepare an area for planting and the knowledge necessary to recognise the

main components of soil.

This study session forms part of the National Certification in Ornamental

Horticulture Learnership at NQF Level 1 and is aligned with the Unit Standard:

Identifying and preparing soils for planting, which carries 4 credits.

Who is it for?

This study session and unit standard forms the skills and knowledge for

people within the ornamental horticulture or landscaping industry who are

required to prepare an area for planting and gives the learner the ability to:

Recognise the differences between topsoil and subsoil.

Understand why topsoil should be conserved.

Identify the three main soil types and their characteristics.

Understand the importance of tilling and digging an area to be planted.

Understand the importance of adding soil enrichments to the ground

before planting.


Workshop Overview



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What's in it for you?

The skills and knowledge acquired in this study session will equip you the

competence needed to be able to prepare an area for planting and help you to

identify:

Topsoil and subsoil.

Sand, loam and clay.

The particle size and textures of each soil type.

This study session will also help you to understand:

The main differences between topsoil and subsoil.

The benefits of planting in topsoil as opposed to subsoil.

The reasons for stockpiling topsoil.

The factors that influence water retention in the three soil types.

The role that particle size plays in determining the infiltration rate of a soil.

The benefits of tilling or digging a soil prior to planting.

The various methods of loosening and turning soil and the depth that each

achieves.

The benefits of adding organic enrichments to the soil before planting.

The improvements in the nutrient levels of a soil, through the addition of

synthetic fertilisers.




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What about assessment?

If you can correctly prepare an area for planting and answer all the knowledge

questions in the summative assessment, you will receive credits for a

competent rating on your assessments.

These credits contribute 1 unit standard and 4 credits towards the National

Certificate in Ornamental Horticulture Learnership at NQF Level 1.

The laid down policies and procedures with regard to assessment,

moderation, RPL and appeals govern this assessment.

You will be rated "Competent" or "Not Yet Competent" against the assessment criteria.




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Unit Standard

Title Identifying and Preparing Soils for planting Number Level 1Credits 4Field Agriculture and Nature ConservationSub field HorticultureIssue date Learning assumed to be in place

None

Specific Outcomes Assessment Criteria

1. Recognise the differences between topsoil and subsoil and explain why topsoil should be conserved

1.1 Describe the main differences between

topsoil and subsoil.

1.2 Explain the benefits of planting in

topsoil as opposed to subsoil.

1.3 Detail the reasons for stockpiling

topsoil.

Range:

Topsoil – organic residue, humus, darker

colour, smoother texture, water retention,

stockpiling.

Subsoil – no organic or humus, lighter

colour, rougher texture.

2. Identify the three main soil types and their characteristics

2.1. Identify the three main soil types.

2.2. Describe the particle sizes and

textures of each soil type.

2.3. Describe the factors that influence Lifestyle CollegeIssue date : January 2005Version 2



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Specific Outcomes Assessment Criteriawater retention in the 3 soil types.

2.4. Describe the role that particle size

plays in determining the infiltration

rate of a soil.

Range:

Sand – large particles, rough texture,

predominantly macro pores, good drainage

and aeration, poor water retention.

Loam – mixture of small and large

particles, moderate drainage and aeration,

good water retention.

Clay – fine particles, smooth texture,

mostly micro pores, poor drainage and

aeration, lengthy water retention.

3. Understand the importance of tilling and digging an area to be planted

3.1. Explain the benefits of tilling or

digging a soil prior to planting.

3.2. Describe the various methods of

loosening and turning soil and the

depth that each achieves.

Range:

Tilling, rotavating, single digging, double

digging, breaking compaction, improving

friability.

4. Understand the importance of adding soil enrichments to the ground before planting

4.1. Describe the benefits of adding

organic enrichments to the soil

before planting.

4.2. Describe the improvements in the

nutrient levels of a soil, through the




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Specific Outcomes Assessment Criteriaaddition of synthetic fertilizers.

Range:

Organic – compost, peat moss, sawdust,

bark, peanut shells, manure, guano, bone

meal, improve water retention, friability,

condition of soil, slow release of nutrients.

Inorganic/synthetic – superphosphates,

agricultural lime, N.P.K. fertilizers, gypsum,

improve chemical composition, balance pH,

increase nutrient level.

Embedded Knowledge

Embedded knowledge is reflected within the assessment criteria of each

specific outcome and must be assessed in its own right, through oral and

written evidence. Observation cannot be the only assessment.




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Critical Cross Field Outcomes

Identify and solve problems in which responses display that responsible

decisions using critical and creative thinking have been made – specific

outcomes 1 and 4.

Work effectively with others as a member of a team, group, organisation or

community. Specific outcome embedded in the learning for this level of

learner.

Organise and manage oneself and one’s activities responsibly and

effectively.

Collect, analyse, organise and critically evaluate information. Specific

outcome 1,2, 3 and 4.

Communicate effectively using visual, mathematical and/or language skills

in the modes of oral and/or written presentation. Specific outcome

embedded in the learning for this level of learner.

Use science and technology effectively and critically, showing

responsibility toward the environment and health of others. Specific

outcome 1,2, 3 and 4.

Demonstrate an understanding of the world as a set of related systems by

recognising that problem-solving contexts do not exist in isolation.

Specific outcome 1, 2, 3 and 4.




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Unit Standard Accreditation and Moderation Options

1. Internal moderation.

2. External moderation.

3. Moderation of assessment will be overseen by the relevant ETQA,

according to the moderation guidelines in the relevant qualification the

agreed ETQA procedures.

4. Internal assessment.

5. External assessment with the relevant registered/accredited industry

body/ETQA.

6. An Assessor accredited by the relevant ETQA, will assess the Learner’s

competency.

7. Formative and summative assessment of qualifying Learners against this

unit standard should be in alignment with the requirements of the NSB.

8. Practical assessment activities will be used that are appropriate to the

contents in which the qualifying Learners are working.

9. Assessment will include self and peer assessment, practical and oral

assessment, observations, questions and answers, etc.

10.Direct observation is required in simulated or actual work conditions.

11.Reporting skills are demonstrated by effective communication, using

verbal and/or writing skills.

12.Assessment is to be structured to include formative and summative

component, as well as the submission of a Portfolio of Evidence.

13.The assessment should ensure that all the specific outcomes, critical cross

field outcomes and embedded knowledge are assessed.

14.Specific outcomes must be assessed in their own right, through oral and

practical evidence and cannot be assessed by observation only.




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Essential embedded knowledge must be assessed in their own right, through

oral and practical evidence and cannot be assessed by observation only.

15.Special outcomes and essential embedded knowledge must be assessed

in relation to each other.

16. If qualifying Learners are able to explain the essential embedded

knowledge, but are unable to perform the specific outcomes, then they

should not be assessed as competent.

17. If qualifying Learners are able to perform specific outcomes, but are

unable to explain the essential embedded knowledge, they should not be

assessed as competent.

18.Evidence of the specified critical cross-field outcomes should be found,

both in performance and in essential embedded knowledge.

19.Assessment activities must be fair, so that all Learners have equal

opportunities. Activities must be free of gender, ethnic or other bias.

20.This unit standard can be assessed together with any other relevant

registered unit standard.




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Who does what?

You are expected to actively take part in the lessons by:

Asking questions.

Planning and preparing for your training and assessment.

Completing the assessment tasks that you are given.

Telling your trainer when you need help or don’t understand.

Your learning will be supported in the following ways:

Your trainer will provide you with all the necessary training material.

Your trainer will manage the learning process during the training.

The assessor will plan and prepare you for assessment, assess your

competence and provide feedback to you and any follow up assessments

that may be necessary.




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An old, old tale about soils…

A long, long time ago, before the Far-off Times, came the time of the Very

Beginnings. A time when all the animals still wore shoes. Yes, you heard

right, the large elephant wore shoes, the muddy hippo wore shoes, the

galloping horse wore shoes and even the burrowing mole wore shoes.

You see at the time of the Very Beginnings the animals didn’t respect the soil

and thought of it as dirty and troublesome.

Some soils were very sandy and the animals kept getting sand in their shoes

– and you know how annoying it is to have sand in your shoes!

Other soils were very muddy and sticky and this clay soil stuck to their shoes

– and you know it is impossible to walk around with muddy, sticky shoes!

So every day the animals would take their sandy shoes off to empty them of

sand and take their clayey sticky shoes off to allow the mud to dry. And very

soon there were shoes scattered all over the land – on the hills, on the plains,

in the valleys and especially near the watering holes. Just imagine how

difficult it must have been trying to find your pair of shoes after having had a

drink at the watering hole!


Introduction



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As time passed the animals become more and more angry and more and

more cross with the soil. Until at last they held a meeting and decided to ask

the plants and earthworms who lived in the soil to help them with this

troublesome soil problem.

They first went to the plants and asked them for their help. This is what the

plants told them:

“In very sandy soils we are often very thirsty because the water runs straight

through the soil and we have to wait for the next rains to fall before we can

drink again.

The sticky, heavy soils hold too much water and our roots can not get enough

air and we nearly drown.

But in the soils where the earthworms live, we have plenty of water and air.

That is why so many of us grow so big and beautiful where the earthworms

live. Go and ask the earthworms for help.”

So the animals went to the earthworms and asked for their help. This is what

the earthworms told them:

“We have a secret that we will share with you, but first you must promise to

respect and look after the soil from now on.”




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Now do you want to know what that secret was?

Then hold up your right hands and promise that you will respect and look after

the soil from now on.

This is the earthworms secret:

“We are the guardians of mother earth. Our job on earth is to make fertile soil

so that healthy plants can grow and so each night we come up to the surface

of the soil and eat decaying plants, pieces of leaves and other plant material.

Inside our stomachs live tiny bacteria that break down the plant material,

which we then give back to the soil through our droppings and this helps to

fertilize the soil in which we live. Our burrows help to bring air into the soil and

so you can say we dig and till to tend the earth.

But there is a lot of soil and not enough of us, so please won’t you help us to

look after the soil, so that the plants can grow healthy and strong and you can

use the plants for food, medicine, shade and shelter?”

And so from generation to generation, the four lessons of the earthworm have

been handed down. As guardians of the earth, these lessons are now passed

to you.

Let’s begin with lesson 1.




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Specific outcomes of this lesson :

Recognise the differences between topsoil and subsoil and explain why topsoil should be conserved.

After you have worked through Lesson 1, you should be able to:

Describe the main differences between topsoil and subsoil.

Explain the benefits of planting in topsoil as opposed to subsoil.

Detail the reasons for stockpiling topsoil.

Soil LayersThe first lesson that the earthworms taught the animals is that when you dig

or burrow into soil like the plant’s roots, you will find that the soil has three

different layers:

TopsoilSubsoil

Parent Material/Bedrock


Lesson 1 : Soil Layers



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The top layer of soil is called the topsoil. This layer of soil is usually

darker in colour than the other layers of soil because it has a high content

of organic material such as leaves and animal litter. As this organic matter

breaks down it makes humus. Humus is rich in nutrients, which gets taken

up by plants and these nutrients help the plants to grow healthy and

strong. Because humus is a soft material it helps bind together very, very

small clay particles into larger crumbs. This helps the soil to absorb and

hold water. In this layer you will also find bacteria, fungi and other small

organisms, although you won’t be able to see these with the naked eye.

The next layer of soil is called the subsoil. This layer of soil is more

rocky, often sticky and normally a lighter colour than the topsoil because

all the irons and organic matter or humus has been washed out. Subsoil is

usually harder to dig than topsoil and it is very difficult for plants to grow in

subsoil.

Underneath the subsoil is the solid bedrock called the parent material this

is where the subsoil and topsoil come from in most soils.

It takes about two thousand years for nature to make 3cms of topsoil and

about 60 years for good humus to form from organic matter in the soil. Topsoil

is valuable because it cannot easily be replaced (it takes many years to form).

But it takes a very short time for man to destroy this topsoil if it is not looked

after properly. Most South African soils are usually very shallow and so when

you dig you must be careful to keep the topsoil on top and not bury it under

subsoil.




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Your Turn…

ACTIVITY 1

Look at the three trays of soil on the table and then answer the following questions:

Which tray holds topsoil?

How do you know this is topsoil?

Which tray holds subsoil?

How do you know this is subsoil?




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Did you notice the main differences between the topsoil and subsoil?

To grow into healthy, strong plants, plants need:

Water.

Nutrients.

Air/oxygen.

Space between soil particles for the roots to grow.

The organic material and humus found in topsoil:

Gives the topsoil a darker colour than the subsoil.

Gives the topsoil a smoother texture than the subsoil, which is rougher

to the touch.

Improves the soil structure.

Absorbs and holds lots of water, this is called the water holding capacity

of the soil. This helps plants to get the water that they need in order to

grow. Subsoil has poor water holding capacity.

Holds nutrients that help the plant to grow. Subsoil has very little plant

food or nutrients.




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Improves the aeration in the soil and allows for more air spaces in the

soil. This helps the plant’s roots to get the air/oxygen that they need.

Subsoil has fewer air spaces and less aeration than topsoil.

Improves the drainage of the soil, so that the plant doesn’t drown.

Subsoil has less organic matter than topsoil and the nutrients leach (get

washed down) through the subsoil.

Why do you think you it is important to know the difference between topsoil and subsoil?

Soil is the “home” of plants and it is from the soil that the plant’s roots gets the

water, nutrients and air/oxygen that the plant needs to grow. But the roots of

plants are not only found in the top of the soil. The plants roots often go deep

down into the soil and so we need to dig into the soil to see what type of soil

the roots of the plant will find.

If the plant’s roots find topsoil the plant will grow strong and healthy, but

topsoil varies in depth from garden to garden from a few centimeters to a

metre or more. If the plant’s roots only have a few centimeters of topsoil and

then lots of subsoil the plant will not be able to reach its full size and spread.

Always remember that without good healthy soil plants will struggle to grow.




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Your Turn…

ACTIVITY 2

What are the main differences between topsoil and subsoil?




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Your Turn…

ACTIVITY 3

Why it is better to plant in topsoil rather than in subsoil?




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Your Turn…

ACTIVITY 4

How would you explain to a group of children why we need to conserve (look after) topsoil?




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Stockpiling Topsoil

Wherever there are new buildings going up or other land construction taking

place that require the topsoil to be cleared or removed, it is important to save

the topsoil. Remember to grow strong healthy plants we need good soil and

you can’t grow strong healthy plants in subsoil. When we save the topsoil,

this is called stockpiling the topsoil.

We need to stockpile topsoil because:

Topsoil is not easily replaced.

Saving topsoil is cheaper than buying new topsoil.

New topsoil that is brought onto the site from another site can be different

to the site’s original topsoil. If the topsoil is too different form the subsoil

on the site you can get problems with the soil draining too quickly or too

slowly.

Once the construction is finished and the subsoil has been shaped, the topsoil

can then be placed back onto the site before the planting stage.




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Your Turn…

ACTIVITY 5

Why do we need to stockpile topsoil?




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Lesson Summary

The soil has three different layers:

Topsoil which is a darker colour and has a smoother texture than subsoil

because of the organic residue and humus material found in the topsoil.

Subsoil which is more rocky, sticker, lighter in colour and rougher in

texture than topsoil and has no organic or humus material.

Parent material or bedrock from which the subsoil and topsoil are usually

made.

We need to look after topsoil because it takes many years to form and cannot

be easily replaced.

To grow into healthy, strong plants, plants need:

Water.

Nutrients.

Air/oxygen.

Space between soil particles for the roots to grow.




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The organic material and humus found in topsoil:

Gives the topsoil a darker colour than the subsoil.

Gives the topsoil a smoother texture than the subsoil, which is rougher to

the touch.

Improves the soil structure.

Absorbs and holds lots of water, this is called the water holding capacity of

the soil. This helps the plant to get the water that they need in order to

grow. Subsoil has poor water holding capacity.

Holds nutrients that help the plant to grow. Subsoil has very little plant

food or nutrients.

Improves the aeration in the soil and allows for more air spaces in the soil.

This helps the plant’s roots to get the air/oxygen that they need. Subsoil

has fewer air spaces and less aeration that topsoil.

Improves the drainage of the soil, so that the plant doesn’t drown. Subsoil

has less organic matter than topsoil and the nutrients leach (get washed

down) through the subsoil.

We need to stockpile topsoil during building or construction projects because:

Topsoil cannot be easily replaced.

Saving this topsoil on a site is cheaper than buying new topsoil.

If new topsoil is brought onto the site it can be different from the original

topsoil. If the topsoil is too different form the subsoil you can get problems

with the soil draining too quickly or too slowly.




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Lesson Checkpoint

Now that you have worked through this lesson, please check that you are able to do all the specific outcomes and meet the assessment criteria:

I can recognise the difference between topsoil and sub soil.

I can describe the main differences between topsoil and subsoil.

I can explain the benefits of planting in topsoil as opposed to subsoil.

I can explain why topsoil should be conserved (looked after).

I can detail the reasons for stockpiling topsoil.




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Notes:




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Identify the three main soil types and their characteristics.


Identify the three main soil types.

Describe the particle sizes and textures of each soil type.

Describe the factors that influence water retention in the three soil types.

Describe the role that particle size plays in determining the infiltration rate of a

soil.

Soil TypesThe second lesson that the earthworms taught the animals is that when you

dig or burrow into the topsoil like the plant’s roots, you will find that the topsoil

doesn’t always look or feel the same. The three main soil types that you will

find when you are preparing an area for planting are:


Sandy soil

Loam soil

Clay soil

Lesson 2 : Soil Types



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When you are preparing an area for planting, you need to see if the soil has a

high sand content or a high clay content or is loamy (a mixture of sand and

clay). You will then know how to prepare the soil for planting.

A simple and cheap way to test which soil type you are working with, is to pick

up a handful of soil, wet the soil slightly and then try to roll your handful of soil

into a sausage shape, this is called the sausage test.

Sandy Soil Loam Soil Clay SoilSandy soil will feel gritty

and rough in your hand.

With sandy soils you will

not be able to form a

sausage shape at all.

Loam soils don’t feel very

rough or very smooth.

With loam sands you will

be able to form a sausage

shape but it will keep

breaking apart.

Wet clay soils are smooth

and will feel sticky in your

hand. Dry clay soils will

feel powdery in your hand.

With clay soils you will be

able to form a sausage that

holds its shape.




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Your Turn…

ACTIVITY 6Look at the three trays of soil and then answer the following questions:

Which tray has clay soil?

How do you know this is clay soil?

Which tray has sandy soil?

How do you know this is sandy soil?

Which tray has loam soil?

How do you know this is loam soil?

Your Turn…




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ACTIVITY 7Fill up one jar with marbles and the other jar with coins.




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Soil Types Particle size and texture

Sandy soil

Sandy soil has large particles (marbles) and a rough texture that

feels harsh and gritty to touch. These large particles of sandy

soil do not hold together when wet and the large air spaces

between these particles are called macro pores.

This soil is light, easy to dig and difficult to compact.

Loam soil

Loam soil has a mixture of small and large particles and a

medium texture that feels neither rough nor smooth to the touch.

This mixture of particles in loam soil means that loam has a

mixture of macro and micro pores.

This soil is fairly easy to dig.

Clay soil

Clay soil has very fine flattened particles (coins) and feels

smooth. These small particles hold together when moist and the

small air spaces between these particles are called micro pores.

This soil is sticky to work with when wet and hard to work with

when dry.

This heavy soil is difficult to dig and compacts easily.




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Your Turn…

ACTIVITY 8What is the particle size and textures of each soil type?




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Your Turn…

ACTIVITY 9Infiltration test

Punch holes into the bottom of three separate tins.

Now fill one tin with clay soil, one with loam soil and one with sandy soil. The tins

should be about ¾ full of soil.

Place all three tins in a place where they can drain freely.

Fill all three tins at the same time to the top with water.

Watch and see how long it takes for the water to drain out of the bottom of each tin.

In which tin did the water go down the quickest?

How do you think this affects plants growing in a soil like this?

In which tin did the water go down the slowest?

How do you think that this would affect plants growing in a soil like this?




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Soil Types Description

Sandy soil

The large particles of sandy soil do not hold together when wet

and the large air spaces between the particles are called macro

pores.

These large air spaces or macro pores:

Hold a high amount of air/oxygen and so the soil has good

aeration.

Allow water to flow through the soil easily and so this soil has

good drainage and a high infiltration (filtering) rate.

But because plant nutrients are water-soluble and coarse sand

has low water holding capacity, water and therefore nutrients are

washed down into the soil, which causes poor nutrition and a

shortage of water for the plants.

To improve this soil add organic material i.e. compost to

increase the soil’s water holding capacity and therefore the

available nutrients to the plants.

Loam soilThe mixture of small and large particles in loam soil means it has




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a mixture of macro and micro pores.

These air spaces:

Hold a medium amount of air/oxygen and so the soil has

moderate aeration.

Allow water to flow through the soil at a moderate rate and so

this soil has moderate drainage and a moderate infiltration

(filtering) rate. This soil contains organic matter that holds

nutrients.

To improve this soil add more organic material i.e. compost to

increases the soils water holding capacity and therefore the

available nutrients to the plants.

Clay soilClay soil has small particles that hold together when moist and

the small air spaces between these particles are called micro

pores.

Even though these pores are small there are a lot of them and

this means that these air spaces or micro pores:

Hold a low amount of air/oxygen and so the soil has poor

aeration.

Allow water to flow through the soil slowly and so this soil has




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low infiltration (filtering) rate and poor drainage. This soil

holds nutrients.

Because this soil can become water logged it leads to lack of air

for the plant’s roots and may cause plant drowning.

To improve this soil add organic material i.e. compost to open up

the soil particles and clump them together to form bigger

particles which allows for better air and water movement to the

plants.




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Your Turn…

ACTIVITY 10What factors influence water retention in the three soil types?

Your Turn…




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ACTIVITY 11What role does particle size play in determining the infiltration rate of a soil?

Lesson Summary




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The three main soil types are:

Sandy soil, which has large particles (macro pores) and a rough texture

that feels harsh and gritty to touch. This soil is light, easy to dig and

difficult to compact.

Loam soil, which has a mixture of small and large particles and a medium

texture that feels neither rough nor smooth to touch. This soil is easy to

dig.

Clay soil, which has fine particles (micro pores) and a smooth texture.

This soil is sticky to work with when wet and hard to work with when dry.

This heavy soil is difficult to dig and compacts easily.

The size of the soil particles determines the infiltration (filtering) rate of a soil

and:

Sandy soil has large particles and air spaces called macro pores. This

soil has a low water holding ability, good drainage and a high infiltration

rate.

Loam soil has a mixture of small and large particles and a mixture of

small and large pores. This soil has medium water holding ability, medium

drainage and a medium infiltration rate.

Clay soil has fine particles and micro pores. This soil has high water

holding ability, poor drainage and a low infiltration rate.

The factors that influence water retention in the three soil types are their

particle and pore size.

Lesson Checkpoint




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I can identify the 3 main soil types and their characteristics.

I can describe the particle size and textures of each soil type.

I can describe the factors that influence water retention in the 3 soil

types.

I can describe the role that particle size plays in determining the

infiltration rate of a soil.




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Notes:




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Understand the importance of tilling and digging an area to be planted


Explain the benefits of tilling or digging a soil prior to planting.

Describe the various methods of loosening and turning soil and the depth that

each achieves.

Soil Structure and Colour

The third lesson that the earthworms taught the animals is that when you dig

or burrow into the topsoil like the plant’s roots, you will find that the topsoil

structure and colour doesn’t always look the same.

The structure and colour of the soil tells us a lot about the quality of the soil.

Remember healthy soil equals healthy plants.


Lesson 3 : Soil Structure and Colour



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Soil Colour:

The colour of the soil can tell us how well the soil is draining:

Colour Tells us: Possible Solutions

Yellow or Grey

Suggests leaching this

means that the nutrients

in the soil are being

washed out and is often

caused by poor

drainage.

It is important to look for poor drainage

conditions before you plant so that you

can decide whether or not artificial

drainage is required.

Possible solutions include to drainage

problems:

If the soil is really badly drained,

install drainage pipes to remove the

excess water.

Where water comes mainly from

adjoining higher land, joining ditches

or drains may be all that is needed.

Where drainage is not possible, only

those plants, which tolerate wet

conditions, can be grown.

Blue-Grey Tells us that water

logging has taken place

and this is often caused

by poor drainage.

Any sign of blue or rusty mottling below the surface.

Where the drainage is

bad in winter but

improves in summer,

rust stains and deposits

appear.

Uniform brown or brown/black to dark brown colours

Shows good drainage and humus content




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Soil Structure:

The structure of the soil is just as important as its texture.

In some soils the particles are clumped together like crumbs on a loaf of

bread and in other soils the particles look as if they are made up of angular

blocks or clods. (These crumbs and the crumb structure of the soil are called

the soils friability).

To find out if your soil has good or bad structure:

Dig out a spade of undisturbed soil, let it drop onto a natural, hard surface and

then notice how it breaks up:

A soil with poor structure will break into block-like clods with flattened surface

and sharply angular sides. A soil with lumpy clods with extremely fine and

almost invisible pores, is a sign of compacting.

A granular or crumb structure is associated with good tilth - a word that is

used to describe the fitness of soil for the growth of plants. A tilth that is good

for lettuces to grow in is not always good for beans or other larger seeds to

grow in. For example, mature roots like to grow in a coarser soil. To build

and maintain good tilth we usually work into the soil bulky organic manure

that rots down into humus.




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Soil structure is compacted through:

Heavy rain, because the raindrops batter the crumbs into individual

particles, which then clog the soil pores. When this layer dries, a hard

crust forms.

People walking or driving over the soil.

Wheeling a wheelbarrow over the soil.

Benefits of tilling or digging soil before planting

Good soil conditions are very important for good plant growth. Though few

gardeners are lucky enough to start off with an ideal soil, almost any soil can

be improved by tilling or digging, composting and fertilizing the soil.

By tilling or digging the soil before planting we create a good growing

environment for plants by:

Breaking soil compaction.

Breaking down soil clods (a clod is a lump or mass of soil).

Breaking up soil pans. These are hard, compacted layers of soil that

sometimes do not allow water to drain.

Loosening the soil.

Introducing air into the soil.

Introducing soil enrichments into the soil.




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This improves the soil by:

Aerating the soil.

Allowing water to easily move down into the soil.

Controlling weeds.

Covering plant residues and stones.

Loosening the soil, especially if the soil is compacted. This allows better

water penetration and better root growth.

All of this helps the plant to grow quicker and easier.

Tilling and digging are also used to shape the soil for landscaping or drainage.




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Your Turn…

ACTIVITY 12

Explain the benefits of tilling or digging a soil before planting?




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Tilling

The word tilling means to turn the soil over either by hand or by using a

mechanical method such as ploughing. Often a generous layer of organic

matter is applied to the top of the soil before tilling so that it can be turned in

at the same time.

Tilling normally turns the soil to a depth of between 25cm and 30cm

depending on the purpose of tilling.

It is always best to try to do all the tilling steps like adding organic matter and

other nutrients all at once – especially if you are using mechanical method to

till. This is called minimum tillage because fewer trips across the soil as it is

tilled will reduce:

The amount of soil compaction.

Costs.

The amount of soil that is blown away by wind or carried away by water.




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To manually till:

Use a spade or a garden fork (if the soil is not too heavy).

Insert the spade or garden fork straight into dry soil and not at an angle.

Don’t till wet soils, especially clay soils as this can damage the structure of

the soil and cause soil pans especially if you are using a mechanical tool.

Now turn the soil over. As you turn the soil over, break up all the clods.

When you are finished turning over the soil, use the head of a garden rake

to firm the soil so that you don’t leave behind big air pockets in the soil.

Now you can use a hoe or the back of a garden rake to push and pull the

soil to break any remaining clods into finer particles and create good tilth.

If fine seeds are to be planted they will need a finer and less coarse tilth to

say, for example, larger shrubs and trees.

The soil has now been tilled in preparation for planting.




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Rotavating

The word rotavating also means to turn over or “rotate” the soil.

Rotavating can be done manually, but the word usually refers to a rotavator or

similar rotavating machine that can be hand or machine operated. This is very

convenient technique to use where large areas need to be tilled.

A rotavator has rotating steel blades that turn the soil. It has a depth adjuster,

but is usually used to turn the soil to a depth of between 15cm and 20cm. The traveling speed of the machine and the rotating speed of the blades

determines how finely the soil will be tilled.

Single Digging:




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Digging the soil is especially important for new gardens and in single digging

the soil is normally turned to a depth of between 25cm to 30cm.

To dig:

Step: How to:

1 Dig a trench about 30cm wide and 25 to 30cm deep (this is a spade

deep).

2 Take this soil and place it near to where you will dig the last trench

because you will use this soil to fill in the last trench.




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Step: How to:3 Loosen the soil at the base of the trench and add soil enrichments.

4 Place the spade into the soil at a right angle to the previous trench.

5 Again place the spade into the soil parallel to the previous trench and

remove an almost square block of soil.

6 Throw this block of soil into the pervious trench turning the soil at the

same time. Soil enrichments are usually added into the turned soil.

7 Repeat steps 3 and 5 until the whole planting area is dug over.

8 Add the soil from the first trench to the last trench.




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How to double dig:

We usually double dig when we are planting bigger plants and plants with big

root systems to improve the soil structure and add nutrients into the soil at

twice the depth of single digging. Double digging turns the soil to a depth of between 50cm to 60cm.

Step: How to:1 Dig a trench about 60cm wide (2 spades width).

2 Take this soil and place it near to where you will dig the last trench

because you will use this soil to fill in the top layer of the last trench.




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Step: How to:

3 Dig down another spade’s depth (double depth). This time only a spade

wide.

4 Remove this soil but keep it separate from the first pile of soil. Do not mix

them.




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Step: How to:

5 Loosen the soil at the bottom of this trench, with a garden fork and add

soil enrichments. (Deep roots will grow here).

6

In the picture you will see that we have shaded the soil at one spade’s

depth in the same way as the soil we removed from that depth in the

beginning and we shaded the soil from the second spade’s depth a

different way. This is to show you that we never mix the two layers of soil.




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Step: How to:

7

Throw the next spade’s width of soil from alongside the double depth

trench into the double depth trench. Remember to turn over the soil and

add soil enrichments. Do the same with the soil from the one spade

depth.

Repeat step 7, moving in the direction of the area to be prepared until you

have covered the planting area.




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Step: How to:

8 Add the soil from the first single depth trench and the soil from the first

double depth trench into the last trench. Again, do not mix them. Add soil

enrichments.




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Basic Principles of Trenching:

Trenching means to dig a trench over the area and then fill it with organic

matter. The original topsoil is then placed on top of the organic matter. The

idea being to provide an area where plants can be given an added chance to

grow. This is only used if no other alternative can be found to improve the

condition of the soil.

Trenching turns the soil to a depth of 30cm.

Step: How to:1 Dig soil to form a trench 30cm deep.

2 Add organic matter to fill in the trench.




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Step: How to:

3 Replace the removed soil (from step 1) on top of the organic matter. This

means that you will have a new soil level.

4 Mix the soil with the organic matter.

5 Continue with steps 1 to 4 until the whole area has been worked over.




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Your Turn…

ACTIVITY 13What methods can be used to loosen and turn the soil?To what depth does each of the methods loosen and turn the soil?




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Lesson Summary

The structure and colour of the soil tells us a lot about the quality of the soil.

Remember healthy soil equals healthy plants

The colour of the soil can tell us how well the soil is draining:

Yellow or grey soil colour suggests that the nutrients are being washed

out or leached out of the soil.

Blue-grey soil colour tells us that water logging has taken place.

Any sign of blue or rusty mottling of the soil below the surface shows us

that the drainage is bad in winter but improves in summer.

Uniform brown or brown/black to dark brown soil colour shows good

drainage and humus content.

The structure of the soil is just as important as its texture and soil structure

can be compacted by:

Heavy rain.

People walking driving over the soil.

Wheeling a wheelbarrow over the soil.




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We need to till or dig the soil before planting to create a good growing

environment for plants. In preparing a bed for planting:

Break soil compaction.

Break down soil clods (a clod is a lump or mass of soil).

Break up soil pans. These are hard, compacted layers of soil that

sometimes do not allow water to drain.

Loosen the soil.

Introduce air into the soil.

This improves the soil by:

Aerating the soil.

Allowing water to easily move down into the soil.

Controlling weeds.

Covering plant residues and stones.

Loosening the soil, especially if the soil is compacted.

All of this helps the plant to grow quicker and easier.

Tilling and digging are also used to shape the soil for landscaping or drainage.




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We can prepare an area for planting by:

Tilling, turning the soil over either by hand or by using a mechanical

method such as ploughing to a depth of between 25cm to 30cm.

Rotavating, turning or rotating the soil to a depth of between 15cm to 20cm.

Single digging, turning the soil to a depth of between 35cm to 30cm. Double digging, turning the soil to twice the depth of single digging. The

soil is turned to a depth of between 50cm to 60cm. Trenching is used if no other alternative can be found to improve the

condition of the soil. A trench is dug over the area to a depth of about 30cm and then filled with organic matter.




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Lesson Checkpoint


I can understand the importance of tilling and digging an area to be

planted.

I can explain the benefits of tilling or digging a soil prior to planting.

I can describe the various methods of loosening and turning soil and the

depth that each achieves.




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Notes:




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Understand the importance of adding soil enrichments to the ground before planting.


Describe the benefits of adding organic enrichments to the soil before planting.

Describe the improvement in the nutrient levels of a soil, through the addition of

synthetic fertilizers.

Soil Improvements

As you have already seen very few people will have ideal soil conditions and

the last lesson that the earthworms taught the animals is that the nutrients in

the soil are used by the plants as food and so soil that has plants growing in it

will need to have nutrients put back into the soil from time to time.

So what nutrients do plants need?


Lesson 4 : Soil Enrichment



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In order for plants to grow strong and healthy they need three main plant nutrients:

Nutrient: Needed for:

Nitrogen (N)Nitrogen moves quickly into the soil and helps the plant to grow

strong, healthy leaves and stems. It is also used by plants to

make chlorophyll which gives leaves their bright green colour.

Phosphorous (P)

Phosphorous moves slowly into the soil, especially in areas with

a low rainfall.

Phosphorous helps the plant to grow strong, healthy roots and

root systems.

Potassium (K) Potassium also helps the plant to develop flowers and fruit and

helps the plant to fight disease.

Although these are the three main nutrients needed by plant, plants also need

smaller amounts of other nutrients, for example sulphur, calcium, zinc,

magnesium, iron, boron and copper.

We can help plants to get the nutrients they need either by adding organic fertilisers into the soil or by adding inorganic or man-made fertilizers into

the soil.




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Feeding plants takes place either:

At planting time.

As part of a regular feeding schedule.

When we see that they are showing signs that they have a nutrient

deficiency.

Let’s begin by taking a look at organic fertilisers.




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Your Turn…

ACTIVITY 14

Place a sponge into a bowl of water and watch what happens.




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Organic Soil Enrichments

Organic matter is the decaying remains of once-living plants and animals or

animal litter that acts like a sponge in the soil and holds water and nutrients.

Because the sun and rain leach the soils in South Africa we need to try to

maintain a high organic matter content.

There are many different kinds of organic matter used to enrich the soil.

(Enrich means to improve the fertility, in other words give the soil important

elements that will help to make the soil better and also help the plants to grow

– or nutrients for plants).

We use organic soil enrichments to:

Improve the soil structure and soil friability. The organic material

helps soil particles to clump together which reduces soil compaction and

increase the tilth, aeration and drainage ability of the soil.

Help the soil to hold more water and nutrients, which increase the

soil’s water holding ability, and increase the soil fertility by slowly releasing

nutrients that are available from their decomposition.

Increase beneficial soil organism levels within the soil, which are

needed to break down the nutrients in the soil so that the plants can take

up the nutrients more easily.




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Reduce soil erosion because the water can infiltrate the soil more easily.

This stops water run-off.

Improve clay soils by loosening the soil particles and improving their tilth,

which helps water and air to go into the soil.

Improve sandy soils by acting like a sponge, which helps the soil to hold

water and nutrients.

The disadvantages of using organic soil enrichments are that they:

Can be expensive to buy.

Can take longer than synthetic soil enrichments to achieve results,

because they first need to be broken down in the soil.

Use nitrogen to break down and form into humus but if they are low in

nitrogen they will take nitrogen, needed by the plants, from the soil to

break down.

Different organic soil enrichments are used for different situations so

allows follow your workplace instructions and rules.




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Organic matter commonly found for use in soils are:Organic matter Description

Compost

Compost is made from a range of decaying plant material and has

a high nutrient holding ability.

Compost mostly has nitrogen and phosphorus but can also

contains potassium depending on what plant material was used

when making it.

Manures Manure is usually made from well-rotted cattle manure and has a

medium nutrient holding ability.

Manure contains nitrogen, phosphorus and potassium.

Peat moss Peat moss is the final form of decayed plant matter and is acid in

nature.

Peat moss is rich in nitrogen, phosphorus and potassium.

Sawdust

Sawdust is wood shavings.

Sawdust lasts for a long time in the soil and is very cheap to use

but must not be used fresh.

Sawdust contains phosphorus and potassium but is low in

nitrogen.

Bark

Bark is usually made from milled pine bark of different sizes that

are in the process of decomposing.

Bark lasts for a long time in the soil and contains nitrogen,

phosphorus and potassium.

Guano Guano is made from Penguin droppings and contains nitrogen,

phosphorus and potassium.

Bone meal

Bone-meal is made from ground bone, which contains nitrogen

and phosphorus.

Phosphorus is a great plant starter since it encourages root

development and is often added to the soil when we plant.

Peanut shells Peanut shells increase the aeration and water holding capacity of

the soil and contain nitrogen.




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Your Turn…

ACTIVITY 15

Organic Matter Experiment:

Activity 15.1:

As a group make 2 piles of sand, each with 20 cupfuls of sand.

Feel the texture of the sand and write this down. Make a note of the colour too.

When you have finished this activity move onto Activity 15.2.

Activity 15.2.

Take 2 cupfuls of compost and mix this into on pile of sand.




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Does this change the colour of the sand, if so, how much? (Compare it to the other pile

of sand).

Is it now lighter or darker in colour? (Compare it to the other pile of sand).

Feel the texture and note if there are any changes. (Compare it to the other pile of

sand).

When you have finished this activity move onto activity 15.3.

Activity 15.3.

Now add 18 cups of compost to the same pile of sand that you added the first two

cups, so that there is now an equal amount of compost and sand.

Again, does this change the colour of the sand, if so, how much? (Compare it to the

other pile of sand).




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Again, feel the texture and note if there are any changes. (Compare it to the other pile

of sand).

How much do you think the water holding ability has changed and why?

Can you see that you need a generous amount of organic matter to make a

marked difference in the soil? So when you are preparing an area for planting

add a generous amount of organic material in relation to your soil type and the

standard practice for the task you are performing. I am sure that you have all

heard the saying “Don’t plant a R50 plant in a 50 cents hole”.




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Your Turn…

ACTIVITY 16

Why do we need to add organic enrichments to the soil before planting?




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Inorganic or Synthetic Soil Enrichments

Synthetic soil enrichments (fertilisers) are used to give plants the nutrients

they need. Synthetic means made by man. Synthetic fertilisers are often

called inorganic because the fertiliser is not made from animal or plant matter.

The difference between organic matter and synthetic fertilizer is that in

organic matter there are only a small percentage of nutrients that become

water-soluble at a time. Remember plants can only take up nutrients once the

nutrient has been dissolved in water. Once synthetic fertilizers are mixed with

water they are available to the plant immediately and therefore faster acting

that organic fertilisers.

We can use synthetic soil enrichments to:

Add individual nutrients that are needed by the plants but are lacking in

the soil into the soil. This improves the chemical composition of the soil.

Balance the pH of the soil. Soil pH is measured on how sweet or sour

the soil is considered to be. A soil with a pH of 7 is neutral soil, below 7 is

considered acidic (sour) and above 7 is considered alkaline (sweet).

Increase nutrient levels of the soil so that the plants can grow strong

and healthy.




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But synthetic soil enrichments can’t:

Change the soil structure.

Make the soil more absorbent.

The advantages of using synthetic fertilisers:

They are easy to use.

They are cheap to transport.

You know what you are putting into the soil.

Synthetic fertilizers:

Used to promote root growth (for example superphosphate and other

“starter “ synthetic fertilizers) should be added at planting stage.

Can be very specialised in their use and should always be applied by very

carefully following the instructions on the packaging and in accordance

with workplace procedures.

Are usually only applied after root growth has started and the plant is

ready to use the nutrients, in other words applied to the top of the soil.

Are extremely useful but if used wrongly they can harm the environment

and plants.

Used wrongly can also causes death or browning of some leaves, this is

called fertilizer burn.




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Common Synthetic Fertilisers

Description

Superphosphate

Superphosphate is made from mined phosphate rock that

is then used by factories to produce superphosphate.

Superphosphate is a good fertiliser to use as a plant

starter as it promotes root growth.

Gypsum

Gypsum is mostly used on clay soils to help the clay

particles to group together to form larger crumbs and

allow better aeration and drainage.

Agricultural lime

Agricultural lime is alkaline and is used to change the soil

pH to a more alkaline one. It also helps clay to form larger

crumbs and allow better aeration and drainage.

Agricultural lime is slow acting.

N.P.K. Fertilisers

N.P.K fertilisers are usually made in granular form and

contain the three main plant food:

N = Nitrogen

P = Phosphorous/Phosphate

K = Potassium




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Your Turn…

ACTIVITY 17

How do synthetic fertilizers improve the nutrient levels of a soil?




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Lesson Summary

In order for plants to grow strong and healthy they need three main plant

nutrients:

Nitrogen (N) which moves quickly into the soil and helps the plant to grow

strong, healthy leaves and stems. Nitrogen is also used by plants to make

chlorophyll which gives leaves their bright green colour.

Phosphorous (P) which moves slowly into the soil, especially in areas

with a low rainfall. Phosphorous helps the plant to grow strong, healthy

roots and root systems.

Potassium (K) which helps the plant to use nitrogen and phosphorus and

also helps the plant to develop flowers and fruit and helps the plant to fight

disease.

Other nutrients which are need in small amounts by the plant are carbon,

sulphur, calcium, zinc, magnesium, iron, boron and copper.

We can help plants to get the nutrients they need either by adding organic fertilisers into the soil or by adding inorganic or man made fertilizers into

the soil.




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We use organic soil enrichments like compost, peat moss, sawdust, bark,

manure, guano, bone meal and peanut shells to:

Improve the soil structure and soil friability.

Help the soil to hold more water and nutrients.

Increase beneficial soil organism levels.

Reduce soil erosion.

Improve clay soils.

Improve sandy soils.

The disadvantages of using organic soil enrichments are that they are

expensive to buy and take longer than synthetic soil enrichments to achieve

results.

We use synthetic soil enrichments like superphosphates, agricultural lime and

N.P.K. fertilizers to:

Improves the chemical composition of the soil.

Balance the pH of the soil.

Increase nutrient levels of the soil.

But synthetic soil enrichments can’t:

Change the soil structure.

Make the soil more absorbent.




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Lesson Checkpoint


I can understand the importance of adding soil enrichments to the

ground before planting.

I can describe the benefits of adding enrichments to the soil before

planting.

I can describe the improvement in nutrient levels of a soil, through the

addition of synthetic fertilizers.




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Notes:




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Your Turn…

ACTIVITY 18

Prepare an area for planting.

Remember to use all you have learnt during this study session:


Study Session Summary



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References

Tandy Cliff., Handbook of Urban Landscape, Mackays of Chatham ltd., Great Britain, 1984.

Edmond J.B. Senn T.L, Andrews F.S, Halfacre R.G, Fundamentals of Horticulture 4th Edition, Mcgraw-Hill, New York, 1975.

Brandy, Nyle C. The Nature and Properties of Soils, 9th Edition, Macmillan, New York 1984.

Kipling, Rudyard Just So Stories 2nd Edition, Puffin books, England, 1994.
