the house plants. Some familiar out-door insects which interfere with

leaf work are the common potato bug, the green cabbage worm, the rose

slug, the elm tree leaf beetle, the canker worm, the tomato worm.

These insects and many others eat the leaves (Fig. 67). They chew and

swallow their food and are called chewing insects. All insects which

chew the leaves of plants can be destroyed by putting poison on their

food. The common poisons used for this purpose are Paris green and

London purple, which contain arsenic, and are used at the rate of one

teaspoonful to a pail of water or one-fourth pound to a barrel of

water. This is sprinkled or sprayed on the leaves of the plants.

Another poison used is white hellebore. This loses its poisoning

qualities when exposed to the air for a time. Therefore it is safer to

use about the flower garden and on plants which are soon to be used as

food or whose fruit is to be used soon, like cabbages and current

bushes. This hellebore is sifted on the plant full strength, or it may

be diluted by mixing one part of hellebore with one or two parts of

flour, plaster, or lime. It is also used in water, putting one ounce

of hellebore in three gallons of water and then spraying it on the

plants. Plants may be sprayed by using a watering pot with a fine rose

or sprinkler, or an old hair-brush or clothes-brush. For large plants

or large numbers of smaller plants spray pumps of various sizes are

used. Sometimes chewing insects on food plants and sucking insects on

all plants are treated by spraying them with soapy solutions or oily

solutions which injure their bodies.

The work of the leaf is also interfered with by diseases which attack

the leaves and cause parts or the whole leaf to turn yellow or brown

or become blistered or filled with holes. The common remedy for most

of these diseases is called the “Bordeaux Mixture.” It is prepared as

follows: Dissolve four pounds of blue vitriol (blue stone, or copper

sulphate) in several gallons of water. Then slake four pounds of lime.

Mix the two and add enough water to make a barrelful. The mixture is

then sprayed on the plants.

For more detailed directions for spraying plants and combating insects

and diseases write to your State Experiment Station and to the United

States Department of Agriculture at Washington, D.C.

[Illustration: FIG. 65.

To show the giving off of gas by leaves, and that sunlight is

necessary for it. The jars contain seaweed. _A_ was set in the sun and

developed enough gas to float part of the plant. _B_ was left in the

darker part of the room and developed very little gas.]

[Illustration: FIG. 66.

Seedling radishes reaching for light.]

[Illustration: FIG. 67.

Elm leaves injured by the "imported elm-tree leaf beetle," a chewing

insect.]

The work of the leaves of house plants is often interfered with by not

giving them sufficient sunlight. Garden and field plants are

sometimes planted so thick that they crowd each other and shut the

light and air from each other, or weeds are allowed to grow and do the

same thing, the result being that the leaves cannot do good work and

the plant becomes weak and sickly. Weeds are destroyed by pulling them

up and exposing their roots to the sun. This should be done before the

weeds blossom, to prevent them from producing fresh seeds for a new

crop of weeds. Some weeds have fleshy roots–for example, dock,

thistle–in which food is stored; these roots go deep in the ground,

and when the upper part of the plant is cut or broken off the root

sends up new shoots to take the place of the old. Some have

underground stems in which food is stored for the same purpose. The

surest way to get rid of such weeds, in fact, of all weeds, is to

prevent their leaves from growing and making starch and digesting food

for them. This is accomplished by constantly cutting off the young

shoots as soon as they appear above the soil, or by growing some crop

that will smother them. The constant effort to make new growth will

soon exhaust the supply of stored food and the weed will die.

CHAPTER XIV

the house plants. Some familiar out-door insects which interfere with

leaf work are the common potato bug, the green cabbage worm, the rose

slug, the elm tree leaf beetle, the canker worm, the tomato worm.

These insects and many others eat the leaves (Fig. 67). They chew and

swallow their food and are called chewing insects. All insects which

chew the leaves of plants can be destroyed by putting poison on their

food. The common poisons used for this purpose are Paris green and

London purple, which contain arsenic, and are used at the rate of one

teaspoonful to a pail of water or one-fourth pound to a barrel of

water. This is sprinkled or sprayed on the leaves of the plants.

Another poison used is white hellebore. This loses its poisoning

qualities when exposed to the air for a time. Therefore it is safer to

use about the flower garden and on plants which are soon to be used as

food or whose fruit is to be used soon, like cabbages and current

bushes. This hellebore is sifted on the plant full strength, or it may

be diluted by mixing one part of hellebore with one or two parts of

flour, plaster, or lime. It is also used in water, putting one ounce

of hellebore in three gallons of water and then spraying it on the

plants. Plants may be sprayed by using a watering pot with a fine rose

or sprinkler, or an old hair-brush or clothes-brush. For large plants

or large numbers of smaller plants spray pumps of various sizes are

used. Sometimes chewing insects on food plants and sucking insects on

all plants are treated by spraying them with soapy solutions or oily

solutions which injure their bodies.

The work of the leaf is also interfered with by diseases which attack

the leaves and cause parts or the whole leaf to turn yellow or brown

or become blistered or filled with holes. The common remedy for most

of these diseases is called the “Bordeaux Mixture.” It is prepared as

follows: Dissolve four pounds of blue vitriol (blue stone, or copper

sulphate) in several gallons of water. Then slake four pounds of lime.

Mix the two and add enough water to make a barrelful. The mixture is

then sprayed on the plants.

For more detailed directions for spraying plants and combating insects

and diseases write to your State Experiment Station and to the United

States Department of Agriculture at Washington, D.C.

[Illustration: FIG. 65.

To show the giving off of gas by leaves, and that sunlight is

necessary for it. The jars contain seaweed. _A_ was set in the sun and

developed enough gas to float part of the plant. _B_ was left in the

darker part of the room and developed very little gas.]

[Illustration: FIG. 66.

Seedling radishes reaching for light.]

[Illustration: FIG. 67.

Elm leaves injured by the "imported elm-tree leaf beetle," a chewing

insect.]

The work of the leaves of house plants is often interfered with by not

giving them sufficient sunlight. Garden and field plants are

sometimes planted so thick that they crowd each other and shut the

light and air from each other, or weeds are allowed to grow and do the

same thing, the result being that the leaves cannot do good work and

the plant becomes weak and sickly. Weeds are destroyed by pulling them

up and exposing their roots to the sun. This should be done before the

weeds blossom, to prevent them from producing fresh seeds for a new

crop of weeds. Some weeds have fleshy roots–for example, dock,

thistle–in which food is stored; these roots go deep in the ground,

and when the upper part of the plant is cut or broken off the root

sends up new shoots to take the place of the old. Some have

underground stems in which food is stored for the same purpose. The

surest way to get rid of such weeds, in fact, of all weeds, is to

prevent their leaves from growing and making starch and digesting food

for them. This is accomplished by constantly cutting off the young

shoots as soon as they appear above the soil, or by growing some crop

that will smother them. The constant effort to make new growth will

soon exhaust the supply of stored food and the weed will die.

CHAPTER XIV

STEMS

WHAT ARE STEMS FOR?

Visit the farm or garden and the fields to examine stems and study

their general appearances and habits of growth. Notice that many

plants, like the trees, bushes and many vegetable and flowering

plants, have stems which are very much branched, while others have

apparently single stems with but few or no branches. Examine these

stems carefully and note that there are leaves on some part of all of

them and that just above the point where each leaf is fastened to the

stem there is a bud which may sometime produce a new branch (Fig. 68).

If the stems of trees and other woody plants be examined in the winter

after the leaves have fallen, it will be seen that the buds are still

there, and that just below each bud is a mark or leaf scar left by the

fallen leaf. These buds are the beginnings of new branches for another

year’s growth. On some branches will be found also flowers and fruit

or seed vessels.

Buds and leaves or buds and leaf scars distinguish stems from roots.

Some plants have stems under the soil as well as above it. These

underground stems resemble roots but can be distinguished from them by

the rings or joints where will be found buds and small scale-like

leaves (Fig. 69). Quitch-grass or wiregrass, Burmuda grass, white

potato and artichoke are examples of underground stems.

Now study the habit of growth of these stems. Notice that:

Some plants grow erect with strong, stiff stems, for example, corn,

sunflower, maple, pine, elm and other trees. Many of these erect stems

have branches reaching out into the air in all directions. Stand under

a tree close to the stem or trunk and look up into the tree and notice

that the leaves are near the outer ends of the branches while in the

centre of the tree the branches are nearly bare. Why is this? If you

remember the work of leaves and the conditions necessary for their

work you will be able to answer this question. Leaves need light and

air for their work, and these erect, branching stems hold the leaves

up and spread them out in the light and air.

Notice that where several trees grow close together, they are

one-sided, and that the longest and largest branches are on the

outside of the group and that they have more leaves than the inner

branches. Why? Why do the trees in thick woods have most of the living

branches and bear most of their leaves away up in the top of the tree?

Some stems instead of standing up erect climb up on other plants or

objects by means of springlike tendrils which twist about the object

and so hold up the slender stem. On the grape vine these tendrils are

slender branches. On the sweet pea and garden pea they are parts of

the leaves. The trumpet creeper and English ivy climb by means of air

roots. The nasturtium climbs by means of its leaf stems.

Other stems get up into the light and air with their leaves by twining

about upright objects. For example, the morning glory and pole bean.

Some stems will be found that spread their leaves out to the sun by

creeping over the ground. Sweet potato, melon, squash, and cucumber

vines are examples of such plants.

One use of the stems of plants then is to support the leaves, flowers

and fruit, and expose them to the much needed light and air.

=Experiment.=–Get a piece of grape vine and cut it into pieces four

or five inches long; notice that the cut surface appears to be full of

little holes. Cut a piece from between joints, place one end in your

mouth and blow hard. It will be found that air can be blown through

the piece of vine. Now pour about an inch of water in a tumbler or cup

and color it with a few drops of red ink. Then stand some of the

pieces of grape vine in the colored water. In a few hours the colored

water will appear at the upper ends of the sticks. Capillary force has

caused the colored water to rise through the small tubes in the vine.

Repeat this experiment with twigs of several kinds of trees and soft

green plants, as elm, maple, sunflower, corn, etc. It will not be

STEMS

WHAT ARE STEMS FOR?

Visit the farm or garden and the fields to examine stems and study

their general appearances and habits of growth. Notice that many

plants, like the trees, bushes and many vegetable and flowering

plants, have stems which are very much branched, while others have

apparently single stems with but few or no branches. Examine these

stems carefully and note that there are leaves on some part of all of

them and that just above the point where each leaf is fastened to the

stem there is a bud which may sometime produce a new branch (Fig. 68).

If the stems of trees and other woody plants be examined in the winter

after the leaves have fallen, it will be seen that the buds are still

there, and that just below each bud is a mark or leaf scar left by the

fallen leaf. These buds are the beginnings of new branches for another

year’s growth. On some branches will be found also flowers and fruit

or seed vessels.

Buds and leaves or buds and leaf scars distinguish stems from roots.

Some plants have stems under the soil as well as above it. These

underground stems resemble roots but can be distinguished from them by

the rings or joints where will be found buds and small scale-like

leaves (Fig. 69). Quitch-grass or wiregrass, Burmuda grass, white

potato and artichoke are examples of underground stems.

Now study the habit of growth of these stems. Notice that:

Some plants grow erect with strong, stiff stems, for example, corn,

sunflower, maple, pine, elm and other trees. Many of these erect stems

have branches reaching out into the air in all directions. Stand under

a tree close to the stem or trunk and look up into the tree and notice

that the leaves are near the outer ends of the branches while in the

centre of the tree the branches are nearly bare. Why is this? If you

remember the work of leaves and the conditions necessary for their

work you will be able to answer this question. Leaves need light and

air for their work, and these erect, branching stems hold the leaves

up and spread them out in the light and air.

Notice that where several trees grow close together, they are

one-sided, and that the longest and largest branches are on the

outside of the group and that they have more leaves than the inner

branches. Why? Why do the trees in thick woods have most of the living

branches and bear most of their leaves away up in the top of the tree?

Some stems instead of standing up erect climb up on other plants or

objects by means of springlike tendrils which twist about the object

and so hold up the slender stem. On the grape vine these tendrils are

slender branches. On the sweet pea and garden pea they are parts of

the leaves. The trumpet creeper and English ivy climb by means of air

roots. The nasturtium climbs by means of its leaf stems.

Other stems get up into the light and air with their leaves by twining

about upright objects. For example, the morning glory and pole bean.

Some stems will be found that spread their leaves out to the sun by

creeping over the ground. Sweet potato, melon, squash, and cucumber

vines are examples of such plants.

One use of the stems of plants then is to support the leaves, flowers

and fruit, and expose them to the much needed light and air.

=Experiment.=–Get a piece of grape vine and cut it into pieces four

or five inches long; notice that the cut surface appears to be full of

little holes. Cut a piece from between joints, place one end in your

mouth and blow hard. It will be found that air can be blown through

the piece of vine. Now pour about an inch of water in a tumbler or cup

and color it with a few drops of red ink. Then stand some of the

pieces of grape vine in the colored water. In a few hours the colored

water will appear at the upper ends of the sticks. Capillary force has

caused the colored water to rise through the small tubes in the vine.

Repeat this experiment with twigs of several kinds of trees and soft

green plants, as elm, maple, sunflower, corn, etc. It will not be

possible to blow through these twigs, but the red water will rise

through them by osmose, and in a few hours will appear at the upper

ends. If some leaves are left on the stems the colored water will

appear in them. Some white flowers can be colored in this way.

In this manner the stem carries plant food dissolved in water from the

roots to the leaves, and after the leaves have digested it carries it

back to various parts of the plant.

The stem then serves as a conductor or a passage for food and moisture

between roots and leaves.

Visit a strawberry bed or search for wild strawberry plants. Notice

that from the older and larger plants are sent out long, slender,

leafless stems with a bud at the tip. These stems are called runners.

Find some runners that have formed roots at the tip and have developed

a tuft of leaves there, forming new plants. Find some black raspberry

plants and notice that some of the canes have bent over and taken root

at the tips sending up a new shoot and thus forming a new plant. You

know how rapidly wire grass and Bermuda grass will overrun the garden

or farm. One way in which they do this is by sending out underground

stems which take root at the joints and so form new plants.

Another use of the stem then is to produce new plants.

On the farm we make use of this habit of stems when we wish to

produce new white potato plants. We cut an old potato in pieces and

plant them. The buds in the eyes grow and form new plants. One way of

getting new grape plants is to take a ripened vine in the fall and cut

it in pieces with two or three buds and plant them so that one or both

of the buds are covered with soil. The pieces will take root and in

the spring will send up new shoots and thus form new plants.

You can obtain new plants from geranium, verbena, nasturtium and many

other flowering plants, by cutting and planting slips or parts of the

stems from them.

In parts of the South new sweet potato plants are obtained by cutting

parts of the stems from growing plants and planting them.

Florists produce large numbers of new plants by taking advantage of

this function of stems.

=Experiment.=–Take a white potato which is a thickened stem and place

it in a warm, dark place. It will soon begin to sprout or send out new

stems, and as these new stems grow the potato shrinks and shrivels up.

Why is this? It is because the starch and other material stored in the

potato are being used to feed the new branches. When we plant potatoes

in the garden and field the new plants produced from the eyes of the

potato are fed by the stored material until they strike root and are

able to take care of themselves.

All stems store food for the future use of the plant.

Annual plants, or those which live but one year, store food in their

stems and leaves during the early part of their growth. During the

fruiting or seed forming season this food material is transferred to

the seeds and there stored, and the stems become woody. This is a fact

to bear in mind in connection with the harvesting of hay or other

fodder crops. If we let the grass stand until the seeds form in the

head, the stem and leaves send their nourishment to the seeds and

become woody and of less value than if cut before the seeds are fully

formed.

In plants of more than one year’s growth the stored food is used to

give the plant a start the following season, or for seed production.

The rapid growth of leaf and twig on trees and shrubs in spring is

made from the food stored in the stem the season before.

Sago is a form of starch stored in the stem of the sago palm for the

future use of the plant.

Maple sugar is made from the food material stored in the trunk of the

maple tree for the rapid growth of twig and leaf in the spring.

possible to blow through these twigs, but the red water will rise

through them by osmose, and in a few hours will appear at the upper

ends. If some leaves are left on the stems the colored water will

appear in them. Some white flowers can be colored in this way.

In this manner the stem carries plant food dissolved in water from the

roots to the leaves, and after the leaves have digested it carries it

back to various parts of the plant.

The stem then serves as a conductor or a passage for food and moisture

between roots and leaves.

Visit a strawberry bed or search for wild strawberry plants. Notice

that from the older and larger plants are sent out long, slender,

leafless stems with a bud at the tip. These stems are called runners.

Find some runners that have formed roots at the tip and have developed

a tuft of leaves there, forming new plants. Find some black raspberry

plants and notice that some of the canes have bent over and taken root

at the tips sending up a new shoot and thus forming a new plant. You

know how rapidly wire grass and Bermuda grass will overrun the garden

or farm. One way in which they do this is by sending out underground

stems which take root at the joints and so form new plants.

Another use of the stem then is to produce new plants.

On the farm we make use of this habit of stems when we wish to

produce new white potato plants. We cut an old potato in pieces and

plant them. The buds in the eyes grow and form new plants. One way of

getting new grape plants is to take a ripened vine in the fall and cut

it in pieces with two or three buds and plant them so that one or both

of the buds are covered with soil. The pieces will take root and in

the spring will send up new shoots and thus form new plants.

You can obtain new plants from geranium, verbena, nasturtium and many

other flowering plants, by cutting and planting slips or parts of the

stems from them.

In parts of the South new sweet potato plants are obtained by cutting

parts of the stems from growing plants and planting them.

Florists produce large numbers of new plants by taking advantage of

this function of stems.

=Experiment.=–Take a white potato which is a thickened stem and place

it in a warm, dark place. It will soon begin to sprout or send out new

stems, and as these new stems grow the potato shrinks and shrivels up.

Why is this? It is because the starch and other material stored in the

potato are being used to feed the new branches. When we plant potatoes

in the garden and field the new plants produced from the eyes of the

potato are fed by the stored material until they strike root and are

able to take care of themselves.

All stems store food for the future use of the plant.

Annual plants, or those which live but one year, store food in their

stems and leaves during the early part of their growth. During the

fruiting or seed forming season this food material is transferred to

the seeds and there stored, and the stems become woody. This is a fact

to bear in mind in connection with the harvesting of hay or other

fodder crops. If we let the grass stand until the seeds form in the

head, the stem and leaves send their nourishment to the seeds and

become woody and of less value than if cut before the seeds are fully

formed.

In plants of more than one year’s growth the stored food is used to

give the plant a start the following season, or for seed production.

The rapid growth of leaf and twig on trees and shrubs in spring is

made from the food stored in the stem the season before.

Sago is a form of starch stored in the stem of the sago palm for the

future use of the plant.

Maple sugar is made from the food material stored in the trunk of the

maple tree for the rapid growth of twig and leaf in the spring.

Cane sugar is the food stored in the sugar cane to produce new plants

the next season.

If we examine the stem of a tree that has been cut down we find that

it is woody, that the wood is arranged in rings or layers and that the

outer part of the stem is covered with bark. We will notice also that

the wood near the centre of the tree is darker than the outer part.

This inner part is called the heart wood of the tree. The lighter

wood is called the sap wood. It is through the outer or sap wood that

the water taken in by the root is passed up to the leaves where the

food which it carries is digested and then sent back to the plant. The

returning digested food is sent back largely through the bark. Between

the bark and the wood is a very thin layer which is called cambium.

This is the active growing tissue of the stem. In the spring it is

very soft and slippery and causes the bark to peel off easily. This

cambium builds a new ring of wood outside of the old wood and a new

ring of bark on the inside of the bark. In this way the tree grows in

diameter.

Now if the bark is injured, or any part of the stem, all parts below

the wound are cut off from the return supply of digested food and

their growth is checked. When such a wound does occur, or if a wound

is made by cutting off a branch, the cambium sets to work to repair

the damage by pushing out a new growth which tends to cover the wound.

We can help this by covering the wound and keeping the air from it to

prevent its drying and to keep disease from attacking it before it is

healed.

HOW THE WORK OF THE STEM MAY BE INTERFERED WITH

If there are any peach trees near by, examine the trunks close to the

ground, even pulling away the soil for a few inches. You will very

likely find a mass of gummy substance oozing from the tree. Pull this

away and in it and in the wood under it will be found one or more

yellowish white worms. These are tree borers. They will be found in

almost all peach trees. They interfere with the work of the stem and

in many cases kill the trees. These worms may be kept somewhat in

check by keeping papers wrapped about the lower part of the tree. But

the surest way to keep them in check is to dig them out, spring and

fall, with a knife and wire.

Borers attack the other fruit trees and also ornamental trees and

shrubs.

Rabbits sometimes gnaw the bark from trees during severe winters.

Careless workmen sometimes injure the bark of trees by allowing plows

and mowing machines or other tools which they are using among them to

come in contact with the trees and injure the bark.

Young trees purchased from the nursery generally have a label fastened

to them with a piece of wire. Unless this wire is removed or is

carefully watched and enlarged from time to time it will cut into the

bark as the stem grows and interfere with its work and often kill the

top of the tree or injure a main branch.

These are a few ways in which the work of the stem is sometimes

checked and the plant injured thereby.

CHAPTER XV

FLOWERS

In our study of the parts of plants the flower and fruit have been

given the last place because in the growing of most farm plants a

knowledge of the functions of the flower is of less importance than

that of the roots, leaves and stems. However, a knowledge of these

parts is necessary for successful fruit culture and some other

horticultural industries.

Cane sugar is the food stored in the sugar cane to produce new plants

the next season.

If we examine the stem of a tree that has been cut down we find that

it is woody, that the wood is arranged in rings or layers and that the

outer part of the stem is covered with bark. We will notice also that

the wood near the centre of the tree is darker than the outer part.

This inner part is called the heart wood of the tree. The lighter

wood is called the sap wood. It is through the outer or sap wood that

the water taken in by the root is passed up to the leaves where the

food which it carries is digested and then sent back to the plant. The

returning digested food is sent back largely through the bark. Between

the bark and the wood is a very thin layer which is called cambium.

This is the active growing tissue of the stem. In the spring it is

very soft and slippery and causes the bark to peel off easily. This

cambium builds a new ring of wood outside of the old wood and a new

ring of bark on the inside of the bark. In this way the tree grows in

diameter.

Now if the bark is injured, or any part of the stem, all parts below

the wound are cut off from the return supply of digested food and

their growth is checked. When such a wound does occur, or if a wound

is made by cutting off a branch, the cambium sets to work to repair

the damage by pushing out a new growth which tends to cover the wound.

We can help this by covering the wound and keeping the air from it to

prevent its drying and to keep disease from attacking it before it is

healed.

HOW THE WORK OF THE STEM MAY BE INTERFERED WITH

If there are any peach trees near by, examine the trunks close to the

ground, even pulling away the soil for a few inches. You will very

likely find a mass of gummy substance oozing from the tree. Pull this

away and in it and in the wood under it will be found one or more

yellowish white worms. These are tree borers. They will be found in

almost all peach trees. They interfere with the work of the stem and

in many cases kill the trees. These worms may be kept somewhat in

check by keeping papers wrapped about the lower part of the tree. But

the surest way to keep them in check is to dig them out, spring and

fall, with a knife and wire.

Borers attack the other fruit trees and also ornamental trees and

shrubs.

Rabbits sometimes gnaw the bark from trees during severe winters.

Careless workmen sometimes injure the bark of trees by allowing plows

and mowing machines or other tools which they are using among them to

come in contact with the trees and injure the bark.

Young trees purchased from the nursery generally have a label fastened

to them with a piece of wire. Unless this wire is removed or is

carefully watched and enlarged from time to time it will cut into the

bark as the stem grows and interfere with its work and often kill the

top of the tree or injure a main branch.

These are a few ways in which the work of the stem is sometimes

checked and the plant injured thereby.

CHAPTER XV

FLOWERS

In our study of the parts of plants the flower and fruit have been

given the last place because in the growing of most farm plants a

knowledge of the functions of the flower is of less importance than

that of the roots, leaves and stems. However, a knowledge of these

parts is necessary for successful fruit culture and some other

horticultural industries.

As with the other parts of the plant our study will not be exhaustive

but will be simply an attempt to bring out one or two important truths

of value to most farmers.

In the study of flowers the specimens used for study will depend upon

the time of the year in which the studies are made and need not

necessarily be the ones used here for illustration.

FUNCTION OR USE OF FLOWERS TO PLANTS

Of what use is the flower to the plant?

You have doubtless noticed that most flowers are followed by fruit or

seed vessels. In fact, the fruit and seeds are really produced from

the flower, and the work of most flowers is to produce seeds in order

to provide for new plants.

[Illustration: FIG. 68.

A horse-chestnut stem showing leaves, buds, and scars where last

year's leaves dropped off.]

[Illustration: FIG. 69.--AN UNDERGROUND STEM

Buds show distinctly at points indicated by _b_.]

To understand how this comes about it will be necessary to study the

parts of the flower and find out their individual uses or functions.

PARTS OF A FLOWER

If we take for our study any of the following flowers: cherry, apple,

buttercup, wild mustard, and start from the outside, we will find an

outer and under part which in most flowers is green. This is called

the calyx (Figs. 70-74). In the buttercup and mustard the calyx is

divided into separate parts called sepals. In the cherry, peach and

apple, the calyx is a cup or tube with the upper edge divided into

lobes.

Above the calyx is a broad spreading corolla which is white or

brightly colored and is divided into several distinct parts called

petals. The petals of one kind of flower are generally different in

shape, size and color from those of other flowers. In some flowers the

petals are united into a corolla of one piece which may be

funnel-shaped, as in the morning glory or petunia of the garden, or

tubular as in the honeysuckle, wheel-shaped as in the tomato and

potato, or of various other forms.

Within the corolla are found several bodies having long, slender stems

with yellow knobs on their tips. These are called stamens. The slender

stems are called stalks or filaments and the knobs anthers. The

anthers of some of the stamens will very likely be found covered with

a fine, yellow powder called pollen. This pollen is produced within

the anther which, when ripe, bursts and discharges the pollen.

The stamens vary greatly in number in different kinds of flowers. In

the centre of the cherry, peach, or mustard flower will be found an

upright slender body called the pistil. In the peach and cherry the

pistil has three parts, a lower rounded, somewhat swollen part called

the ovary, a slender stem arising from it called the style, and a

slight enlargement at the top of the style called the stigma. The

stigma is generally roughened or sticky. If the ovary is split open,

within it will be found a little body called an ovule, which is to

develop into a seed.

In the apple flower the pistils will be found to have one ovary with

five styles and stigmas and in the ovary will be several ovules.

In the buttercup will be found a large number of small pistils, each

consisting of an ovary and stigma.

The parts of different flowers will be found to vary in color, in

shape, in relative size and in number. In some flowers one or more of

the parts will be found wanting.

As with the other parts of the plant our study will not be exhaustive

but will be simply an attempt to bring out one or two important truths

of value to most farmers.

In the study of flowers the specimens used for study will depend upon

the time of the year in which the studies are made and need not

necessarily be the ones used here for illustration.

FUNCTION OR USE OF FLOWERS TO PLANTS

Of what use is the flower to the plant?

You have doubtless noticed that most flowers are followed by fruit or

seed vessels. In fact, the fruit and seeds are really produced from

the flower, and the work of most flowers is to produce seeds in order

to provide for new plants.

[Illustration: FIG. 68.

A horse-chestnut stem showing leaves, buds, and scars where last

year's leaves dropped off.]

[Illustration: FIG. 69.--AN UNDERGROUND STEM

Buds show distinctly at points indicated by _b_.]

To understand how this comes about it will be necessary to study the

parts of the flower and find out their individual uses or functions.

PARTS OF A FLOWER

If we take for our study any of the following flowers: cherry, apple,

buttercup, wild mustard, and start from the outside, we will find an

outer and under part which in most flowers is green. This is called

the calyx (Figs. 70-74). In the buttercup and mustard the calyx is

divided into separate parts called sepals. In the cherry, peach and

apple, the calyx is a cup or tube with the upper edge divided into

lobes.

Above the calyx is a broad spreading corolla which is white or

brightly colored and is divided into several distinct parts called

petals. The petals of one kind of flower are generally different in

shape, size and color from those of other flowers. In some flowers the

petals are united into a corolla of one piece which may be

funnel-shaped, as in the morning glory or petunia of the garden, or

tubular as in the honeysuckle, wheel-shaped as in the tomato and

potato, or of various other forms.

Within the corolla are found several bodies having long, slender stems

with yellow knobs on their tips. These are called stamens. The slender

stems are called stalks or filaments and the knobs anthers. The

anthers of some of the stamens will very likely be found covered with

a fine, yellow powder called pollen. This pollen is produced within

the anther which, when ripe, bursts and discharges the pollen.

The stamens vary greatly in number in different kinds of flowers. In

the centre of the cherry, peach, or mustard flower will be found an

upright slender body called the pistil. In the peach and cherry the

pistil has three parts, a lower rounded, somewhat swollen part called

the ovary, a slender stem arising from it called the style, and a

slight enlargement at the top of the style called the stigma. The

stigma is generally roughened or sticky. If the ovary is split open,

within it will be found a little body called an ovule, which is to

develop into a seed.

In the apple flower the pistils will be found to have one ovary with

five styles and stigmas and in the ovary will be several ovules.

In the buttercup will be found a large number of small pistils, each

consisting of an ovary and stigma.

The parts of different flowers will be found to vary in color, in

shape, in relative size and in number. In some flowers one or more of

the parts will be found wanting.

Examine a number of flowers and find the parts.

FUNCTIONS OF THE PARTS OF THE FLOWERS

Now what are the uses of these parts of the flower?

[Illustration: FIG. 70.--FLOWER OF CHERRY.

_a_, pistil; _b_, stamen; _c_, corolla; _d_, calyx; _e_, section of

flower showing ovary with ovule. (Drawing by M.E. Feltham.)]

[Illustration: FIG. 71.

1. Flower of apple; _b_, stamens; _c_, corolla; _d_, calyx. 2. Section

of same; _a_, style; _e_, compound ovary; _f_, filament; _g_, anther.

(Drawing by M.E. Feltham.)]

[Illustration: FIG. 72.

_A._ Pistil of flowering raspberry; _e_, ovary; _t_, style; _s_,

stigma. _B._ Stamen of flowering raspberry; _f_, filament; _g_,

anther; _p_, pollen.]

[Illustration: FIG. 73.--FLOWER OF BUTTERCUP.

_c_, petals; _d_, sepals; _h_, ripened pistils, or fruit. (Drawing by

M.E. Feltham.)]

If we watch a flower of the peach or cherry from week to week, we will

see that the pistil develops into a peach or cherry which bears within

a seed from which a new plant will be produced if the seed is

placed under conditions necessary for germination or sprouting.

The pistils of the flowers of other plants will be found to develop

into fleshy fruits, hard nuts, dry pods or husks containing one or

more seeds.

The work of the pistil or pistils of flowers then is to furnish seeds

for the production of new plants.

The botanists tell us that a pistil will not produce seeds unless it

is fertilized by pollen from the same kind of flower falling on its

stigma.

The work of the stamen then is to produce pollen to fertilize the

pistils. Pistils and stamens are both necessary for the production of

fruit and seed. They are therefore called the essential or necessary

parts of the flower.

The botanists also tell us that nature has provided that in most cases

the pistils shall be fertilized by the pollen of some other flower

than their own, as this produces stronger seeds.

How is the pollen carried from flower to flower?

Go into the garden or field and watch the bees and butterflies flying

about the flowers, resting on them and crawling into them. They are

seeking for nectar which the flower secretes. As they visit plant

after plant, feeding from many flowers, their bodies become more or

less covered with pollen as they brush over the stamens. Some of this

pollen in turn gets rubbed off on the stigmas of the pistils and they

become fertilized. Thus the bees and some other insects have become

necessary as pollen carriers for some of the flowers and the flowers

in turn feed them with sweet nectar.

This gives us a hint as to one use of the corollas which spreads out

such broad, brightly-colored, conspicuous petals. It must be that they

are advertisements or sign boards to attract the bees and to tell them

where they can find nectar and so lead them unconsciously to carry

pollen from flower to flower to fertilize the pistils. The act of

carrying pollen to the pistil is called pollination, and carrying

pollen from the stamens of one flower to the pistil of another flower

is called cross pollination.

If we examine a blossom bud just before it opens we will see only the

calyx. Everything else will be wrapped up inside of it. Evidently,

then, the calyx is a protecting covering for the other parts of the

Examine a number of flowers and find the parts.

FUNCTIONS OF THE PARTS OF THE FLOWERS

Now what are the uses of these parts of the flower?

[Illustration: FIG. 70.--FLOWER OF CHERRY.

_a_, pistil; _b_, stamen; _c_, corolla; _d_, calyx; _e_, section of

flower showing ovary with ovule. (Drawing by M.E. Feltham.)]

[Illustration: FIG. 71.

1. Flower of apple; _b_, stamens; _c_, corolla; _d_, calyx. 2. Section

of same; _a_, style; _e_, compound ovary; _f_, filament; _g_, anther.

(Drawing by M.E. Feltham.)]

[Illustration: FIG. 72.

_A._ Pistil of flowering raspberry; _e_, ovary; _t_, style; _s_,

stigma. _B._ Stamen of flowering raspberry; _f_, filament; _g_,

anther; _p_, pollen.]

[Illustration: FIG. 73.--FLOWER OF BUTTERCUP.

_c_, petals; _d_, sepals; _h_, ripened pistils, or fruit. (Drawing by

M.E. Feltham.)]

If we watch a flower of the peach or cherry from week to week, we will

see that the pistil develops into a peach or cherry which bears within

a seed from which a new plant will be produced if the seed is

placed under conditions necessary for germination or sprouting.

The pistils of the flowers of other plants will be found to develop

into fleshy fruits, hard nuts, dry pods or husks containing one or

more seeds.

The work of the pistil or pistils of flowers then is to furnish seeds

for the production of new plants.

The botanists tell us that a pistil will not produce seeds unless it

is fertilized by pollen from the same kind of flower falling on its

stigma.

The work of the stamen then is to produce pollen to fertilize the

pistils. Pistils and stamens are both necessary for the production of

fruit and seed. They are therefore called the essential or necessary

parts of the flower.

The botanists also tell us that nature has provided that in most cases

the pistils shall be fertilized by the pollen of some other flower

than their own, as this produces stronger seeds.

How is the pollen carried from flower to flower?

Go into the garden or field and watch the bees and butterflies flying

about the flowers, resting on them and crawling into them. They are

seeking for nectar which the flower secretes. As they visit plant

after plant, feeding from many flowers, their bodies become more or

less covered with pollen as they brush over the stamens. Some of this

pollen in turn gets rubbed off on the stigmas of the pistils and they

become fertilized. Thus the bees and some other insects have become

necessary as pollen carriers for some of the flowers and the flowers

in turn feed them with sweet nectar.

This gives us a hint as to one use of the corollas which spreads out

such broad, brightly-colored, conspicuous petals. It must be that they

are advertisements or sign boards to attract the bees and to tell them

where they can find nectar and so lead them unconsciously to carry

pollen from flower to flower to fertilize the pistils. The act of

carrying pollen to the pistil is called pollination, and carrying

pollen from the stamens of one flower to the pistil of another flower

is called cross pollination.

If we examine a blossom bud just before it opens we will see only the

calyx. Everything else will be wrapped up inside of it. Evidently,

then, the calyx is a protecting covering for the other parts of the

flower until blossoming time.

The corolla will be found carefully folded within the calyx and also

helps protect the stamens and pistil.

Some flowers do not produce bright-colored corollas to attract the

bees, for examples, the flowers of the grasses, wheat, corn, and other

grains, the willows, butternuts, elms, pines and others. But they

produce large amounts of pollen which is carried by the wind to the

pistils.

You have sometimes noticed in the spring that after a rain the pools

of water are surrounded by a ring of yellow powder and you have

perhaps thought it was sulphur. It was not sulphur but was composed of

millions of pollen grains from flowers. One spring Sunday I laid my

hat on the seat in church. When I picked it up at the end of the

service I found considerable dust on it. I brushed the dust off, but

on reaching home I found some remaining and noticed that is was

yellow, so I examined it with a magnifying glass and found that it was

nearly all pollen grains. Then I rubbed my finger across a shelf in my

room and found it slightly dusty; the magnifying glass showed me that

this dust was half pollen. This shows what a great amount of pollen is

produced and discharged into the air, and it shows that very few

pistils could escape even if they were under cover of a building.

To make sure of cross pollination nature has in some cases placed the

stamens and pistils in different flowers on the same plant. This will

be found true of the flowers of the squashes, melons and cucumber.

Below some of the flower buds will be seen a little squash, melon or

cucumber (Fig. 75). These are the ovaries of pistils and the stigmas

will be found within the bud or will be seen when the bud opens. But

no stamen will be found here. Other flowers on these plants will be

found to possess only stamens. These staminate flowers produce pollen

and then die. They do not produce any fruit, but their pollen is

necessary for the little cucumbers, squashes and melons to develop.

Another example is the corn plant. Here the pistils are on the ear,

the corn silk being the styles and stigmas, while the pollen is

produced in the tassel at the top of the plant.

With some plants we find that not only are the pistils and stamens in

separate flowers but the staminate and pistilate flowers are placed on

different plants. This will be found true of the osage orange and the

willow.

In many flowers that have both stamens and pistils or are perfect

flowers the stigmas and pollen ripen at different times.

With some varieties of fruit it is found that the pistils cannot be

fertilized by pollen of the same variety. This is true of most of our

native plums. For example, the pistils of the wild goose plum cannot

be fertilized by pollen of wild goose plums even if it comes from

other trees than the one bearing the pistils. They must have pollen

from another variety of plum.

VALUE OF A KNOWLEDGE OF THE FLOWER

Many times it happens that a farmer or a gardener wants to start a

strawberry bed and buys plants of a variety of berries that have the

reputation of being very productive. He plants them and cultivates

them carefully, and at the proper time they blossom very freely, and

there is promise of a large crop, yet very few berries appear and this

continues to be the case. Not satisfied with them he buys another

variety and plants near them, and after that the old bed becomes very

productive. Now why is this? It happens that the flowers of some

varieties of strawberries have a great many pistils but no stamens,

or very few stamens, and there is not pollen enough to fertilize all

of the blossoms, and when such a variety is planted it is necessary to

plant near it some variety that produces many stamens and therefore

pollen enough to fertilize both varieties in order to be sure of a

crop. Those strawberries which produce flowers with only pistils are

called pistilate varieties, while those with both stamens and pistils

are called perfect varieties (Fig. 78). In planting them there should

be at least one row of a perfect variety to every four or five

flower until blossoming time.

The corolla will be found carefully folded within the calyx and also

helps protect the stamens and pistil.

Some flowers do not produce bright-colored corollas to attract the

bees, for examples, the flowers of the grasses, wheat, corn, and other

grains, the willows, butternuts, elms, pines and others. But they

produce large amounts of pollen which is carried by the wind to the

pistils.

You have sometimes noticed in the spring that after a rain the pools

of water are surrounded by a ring of yellow powder and you have

perhaps thought it was sulphur. It was not sulphur but was composed of

millions of pollen grains from flowers. One spring Sunday I laid my

hat on the seat in church. When I picked it up at the end of the

service I found considerable dust on it. I brushed the dust off, but

on reaching home I found some remaining and noticed that is was

yellow, so I examined it with a magnifying glass and found that it was

nearly all pollen grains. Then I rubbed my finger across a shelf in my

room and found it slightly dusty; the magnifying glass showed me that

this dust was half pollen. This shows what a great amount of pollen is

produced and discharged into the air, and it shows that very few

pistils could escape even if they were under cover of a building.

To make sure of cross pollination nature has in some cases placed the

stamens and pistils in different flowers on the same plant. This will

be found true of the flowers of the squashes, melons and cucumber.

Below some of the flower buds will be seen a little squash, melon or

cucumber (Fig. 75). These are the ovaries of pistils and the stigmas

will be found within the bud or will be seen when the bud opens. But

no stamen will be found here. Other flowers on these plants will be

found to possess only stamens. These staminate flowers produce pollen

and then die. They do not produce any fruit, but their pollen is

necessary for the little cucumbers, squashes and melons to develop.

Another example is the corn plant. Here the pistils are on the ear,

the corn silk being the styles and stigmas, while the pollen is

produced in the tassel at the top of the plant.

With some plants we find that not only are the pistils and stamens in

separate flowers but the staminate and pistilate flowers are placed on

different plants. This will be found true of the osage orange and the

willow.

In many flowers that have both stamens and pistils or are perfect

flowers the stigmas and pollen ripen at different times.

With some varieties of fruit it is found that the pistils cannot be

fertilized by pollen of the same variety. This is true of most of our

native plums. For example, the pistils of the wild goose plum cannot

be fertilized by pollen of wild goose plums even if it comes from

other trees than the one bearing the pistils. They must have pollen

from another variety of plum.

VALUE OF A KNOWLEDGE OF THE FLOWER

Many times it happens that a farmer or a gardener wants to start a

strawberry bed and buys plants of a variety of berries that have the

reputation of being very productive. He plants them and cultivates

them carefully, and at the proper time they blossom very freely, and

there is promise of a large crop, yet very few berries appear and this

continues to be the case. Not satisfied with them he buys another

variety and plants near them, and after that the old bed becomes very

productive. Now why is this? It happens that the flowers of some

varieties of strawberries have a great many pistils but no stamens,

or very few stamens, and there is not pollen enough to fertilize all

of the blossoms, and when such a variety is planted it is necessary to

plant near it some variety that produces many stamens and therefore

pollen enough to fertilize both varieties in order to be sure of a

crop. Those strawberries which produce flowers with only pistils are

called pistilate varieties, while those with both stamens and pistils

are called perfect varieties (Fig. 78). In planting them there should

be at least one row of a perfect variety to every four or five

pistilate rows.

[Illustration: FIG. 74.

A magnolia flower showing central column of pistils and stamens, the

pistils being above and the stamens below them.]

[Illustration: FIG. 75.--FLOWERS OF SQUASH.

_A_, pistillate flower; _B_, staminate flower. A means of insuring

cross-pollination.]

We have learned that certain varieties of plums cannot be fertilized

by pollen from the same variety, and to make them fruitful some other

variety must be planted among them to produce pollen that will make

them fruitful. This is more or less true of all our fruits. Therefore

it is not best generally to plant one variety of fruit by itself. Not

knowing this some orchardists have planted large blocks of a single

variety of fruit which has been unfruitful till some other varieties

have been planted near them or among them.

A knowledge of the necessity of pollination is very important to those

gardeners who grow cucumbers, tomatoes, melons and other fruiting

plants in greenhouses. Here in most cases the pollination is done by

hand.

We noticed that nature provides that most of the flowers shall be

cross pollinated. This is particularly true of the flowers of the

fruit trees, and for this reason it is impossible to get true

varieties of fruit from seed. For example, if we plant seeds of the

wine sap apple, the new trees produced from them will not produce the

same kind of apple but each tree will produce something different and

they will very likely all be poorer than the parent fruit. This is

because of the mixture of pollens which fertilize the pistils. Knowing

this fact the nurseryman plants apple seeds and grows apple seedlings.

When these get to be the size of a lead pencil he grafts them, that

is, he digs them up, cuts off the tops away down to the root and then

takes twigs from the variety he wishes to grow and sets or splices

these twigs in the roots of the seedlings and then plants them. The

root and the new top unite and produce a tree that bears the same kind

of fruit as that produced by the tree from which the twig was taken.

These are a few of the reasons why it is well to know something about

flowers and their work.

[Illustration: FIG. 76.--FLOWER OF A LILY.

Notice how the stigma and the anthers are kept as far as possible from

each other to guard against self-pollination and to insure

cross-pollination.]

[Illustration: FIG. 77.

Bud and flower of jewel-weed, or "touch-me-not." _A._ Interior of bud.

Stamens are seen, but there appears to be no pistil. _B._ Section of

bud showing the pistil concealed behind the stamens. _C._ Bee entering

flower comes in contact with stamens and is loaded with pollen. _D._

Same bee entering older flower. The stamens have ripened and been

pushed off by the lengthened pistil, which is brushed by the back of

the bee, and thus is pollinated. This is a contrivance to insure

cross-pollination.]

[Illustration: FIG. 78.

_A._ Pistillate flower of strawberry.

_B._ Perfect flower of strawberry. (Drawing by M.E. Feltham.)]

FRUIT

The pistil develops and forms the fruit of the plant. This fruit bears

seed for the production of new plants. This fruit may be a dry pod

like the bean or pea, or it may be a fleshy fruit like the apple or

plum. Now the developing pistil or fruit may be checked in its work of

seed production by insects and diseases, and to secure good fruit it

is in many cases necessary to spray the fruits just as the leaves

are sprayed, to keep these insects and diseases in check.

The fruits of most plants, like the leaves, need light and air for

their best development, and it sometimes happens that the branches of

pistilate rows.

[Illustration: FIG. 74.

A magnolia flower showing central column of pistils and stamens, the

pistils being above and the stamens below them.]

[Illustration: FIG. 75.--FLOWERS OF SQUASH.

_A_, pistillate flower; _B_, staminate flower. A means of insuring

cross-pollination.]

We have learned that certain varieties of plums cannot be fertilized

by pollen from the same variety, and to make them fruitful some other

variety must be planted among them to produce pollen that will make

them fruitful. This is more or less true of all our fruits. Therefore

it is not best generally to plant one variety of fruit by itself. Not

knowing this some orchardists have planted large blocks of a single

variety of fruit which has been unfruitful till some other varieties

have been planted near them or among them.

A knowledge of the necessity of pollination is very important to those

gardeners who grow cucumbers, tomatoes, melons and other fruiting

plants in greenhouses. Here in most cases the pollination is done by

hand.

We noticed that nature provides that most of the flowers shall be

cross pollinated. This is particularly true of the flowers of the

fruit trees, and for this reason it is impossible to get true

varieties of fruit from seed. For example, if we plant seeds of the

wine sap apple, the new trees produced from them will not produce the

same kind of apple but each tree will produce something different and

they will very likely all be poorer than the parent fruit. This is

because of the mixture of pollens which fertilize the pistils. Knowing

this fact the nurseryman plants apple seeds and grows apple seedlings.

When these get to be the size of a lead pencil he grafts them, that

is, he digs them up, cuts off the tops away down to the root and then

takes twigs from the variety he wishes to grow and sets or splices

these twigs in the roots of the seedlings and then plants them. The

root and the new top unite and produce a tree that bears the same kind

of fruit as that produced by the tree from which the twig was taken.

These are a few of the reasons why it is well to know something about

flowers and their work.

[Illustration: FIG. 76.--FLOWER OF A LILY.

Notice how the stigma and the anthers are kept as far as possible from

each other to guard against self-pollination and to insure

cross-pollination.]

[Illustration: FIG. 77.

Bud and flower of jewel-weed, or "touch-me-not." _A._ Interior of bud.

Stamens are seen, but there appears to be no pistil. _B._ Section of

bud showing the pistil concealed behind the stamens. _C._ Bee entering

flower comes in contact with stamens and is loaded with pollen. _D._

Same bee entering older flower. The stamens have ripened and been

pushed off by the lengthened pistil, which is brushed by the back of

the bee, and thus is pollinated. This is a contrivance to insure

cross-pollination.]

[Illustration: FIG. 78.

_A._ Pistillate flower of strawberry.

_B._ Perfect flower of strawberry. (Drawing by M.E. Feltham.)]

FRUIT

The pistil develops and forms the fruit of the plant. This fruit bears

seed for the production of new plants. This fruit may be a dry pod

like the bean or pea, or it may be a fleshy fruit like the apple or

plum. Now the developing pistil or fruit may be checked in its work of

seed production by insects and diseases, and to secure good fruit it

is in many cases necessary to spray the fruits just as the leaves

are sprayed, to keep these insects and diseases in check.

The fruits of most plants, like the leaves, need light and air for

their best development, and it sometimes happens that the branches of

the fruit trees grow so thick that the fruits do not get sufficient

light and air. This makes it necessary to thin the branches or in

other words to prune the tree. Some trees also start more fruit than

they can properly feed and as a result the ripened fruits are small

and the tree is weakened. This makes it necessary to thin the fruits

while they are young and undeveloped.

PART II

Soil Fertility as Affected by Farm Operations and Farm Practices

THE FIRST BOOK OF FARMING

PART II

_Soil Fertility as Affected by Farm Operations and Farm Practices_

CHAPTER XVI

A FERTILE SOIL

What is a fertile soil?

The expression a fertile soil is often used as meaning a soil that is

rich in plant food. In its broader and truer meaning a fertile soil is

one in which are found all the conditions necessary to the growth and

development of plant roots.

These conditions, as learned in Chapter II, are as follows:

The root must have a firm yet mellow soil.

It must be well supplied with moisture.

It must be well supplied with air.

It must have a certain amount of heat.

It must be supplied with available plant food.

In order to furnish these needs or conditions the soil must possess

certain characteristics or properties.

These properties may be grouped under three heads:

Physical properties; the moisture, heat and air conditions needed by

the roots.

Biological properties; the work of very minute living organisms in the

soil.

Chemical properties; plant food in the soil.

PHYSICAL PROPERTIES OF A FERTILE SOIL

Three very important physical properties of a fertile soil are its

Power to take water falling on the surface.

Power to absorb water from below.

Power to hold water.

The fertile soil must possess all three of these powers. The relative

degrees to which these three powers or properties are possessed

determine more than anything else the kind of crops or the class of

crops that will grow best on a given soil.

the fruit trees grow so thick that the fruits do not get sufficient

light and air. This makes it necessary to thin the branches or in

other words to prune the tree. Some trees also start more fruit than

they can properly feed and as a result the ripened fruits are small

and the tree is weakened. This makes it necessary to thin the fruits

while they are young and undeveloped.

PART II

Soil Fertility as Affected by Farm Operations and Farm Practices

THE FIRST BOOK OF FARMING

PART II

_Soil Fertility as Affected by Farm Operations and Farm Practices_

CHAPTER XVI

A FERTILE SOIL

What is a fertile soil?

The expression a fertile soil is often used as meaning a soil that is

rich in plant food. In its broader and truer meaning a fertile soil is

one in which are found all the conditions necessary to the growth and

development of plant roots.

These conditions, as learned in Chapter II, are as follows:

The root must have a firm yet mellow soil.

It must be well supplied with moisture.

It must be well supplied with air.

It must have a certain amount of heat.

It must be supplied with available plant food.

In order to furnish these needs or conditions the soil must possess

certain characteristics or properties.

These properties may be grouped under three heads:

Physical properties; the moisture, heat and air conditions needed by

the roots.

Biological properties; the work of very minute living organisms in the

soil.

Chemical properties; plant food in the soil.

PHYSICAL PROPERTIES OF A FERTILE SOIL

Three very important physical properties of a fertile soil are its

Power to take water falling on the surface.

Power to absorb water from below.

Power to hold water.

The fertile soil must possess all three of these powers. The relative

degrees to which these three powers or properties are possessed

determine more than anything else the kind of crops or the class of

crops that will grow best on a given soil.

These powers depend, as we learned in Chapter IV, on the texture of

the soil or the relative amounts of sand, silt, clay and humus

contained in the soil.

The power of admitting a free circulation of air through its pores is

also an important property of a fertile soil, for air is necessary to

the life and growth of the roots. This property is dependent also on

texture.

Two other important properties of a fertile soil are power to absorb

and power to hold heat. These depend upon the power of the soil to

take in warm rain and warm air, and also upon density and color. The

denser or more compact soil and the darker soil having greater power

to absorb heat.

The compactness of the soil which gives it greater powers to absorb

heat weakens its powers to hold it, because the compactness allows

more rapid conduction of heat to the surface, where it is lost by

radiation.

The more moisture a soil holds, the weaker is its heat-holding power,

because the heat is used in warming and evaporating water from the

surface of the soil.

These important properties or conditions of moisture, heat and air,

are, as we have seen, dependent on soil texture and color, which in

turn are dependent upon the relative amounts of sand, clay and humus

in the soil. We are able to control soil texture and therefore these

physical properties to a certain degree by means of tillage and the

addition of organic matter or humus (see Chapter IV).

BIOLOGICAL PROPERTIES OF A FERTILE SOIL

Biology is the story or science of life; and the biological properties

of the soil have to do with living organisms in the soil.

The soil of every fertile field is full of very small or microscopic

plants called bacteria or germs. They are said to be microscopic

because they are so small that they cannot be seen without the aid of

a powerful magnifying glass or microscope. They are so small that it

would take about 10,000 average-sized soil bacteria or soil germs

placed side by side to measure one inch.

A knowledge of three classes of these soil germs is of great

importance to the farmer. These three classes of germs are:

Nitrogen-fixing germs.

Nitrifying germs.

Denitrifying germs.

NITROGEN-FIXING GERMS

We learned in Chapter VIII that nitrogen is one of the necessary

elements of plant food, and that although the air is four-fifths

nitrogen, most plants must take their nitrogen from the soil. There

is, however, a class of plants called legumes which can use the

nitrogen of the air. Clover, alfalfa, lucern, cowpea, soy bean, snap

bean, vetch and similar plants are legumes. These legumes get the

nitrogen from the air in a very curious and interesting manner. It is

done through the aid of bacteria or germs.

Carefully dig up the roots of several legumes and wash the soil from

them. On the roots will be found many small enlargements like root

galls; these are called nodules or tubercles. On clover roots these

nodules are about the size of the head of a pin while on the soy bean

and cowpea they are nearly as large as a pea (see Fig. 34). These

nodules are filled with bacteria or germs and these germs have the

power of taking nitrogen from the air which finds its way into the

soil. After using the nitrogen the germ gives it to the plant which

then uses it to build stem, leaves and roots. In this way the legumes

are able to make use of the nitrogen of the soil air, and these germs

These powers depend, as we learned in Chapter IV, on the texture of

the soil or the relative amounts of sand, silt, clay and humus

contained in the soil.

The power of admitting a free circulation of air through its pores is

also an important property of a fertile soil, for air is necessary to

the life and growth of the roots. This property is dependent also on

texture.

Two other important properties of a fertile soil are power to absorb

and power to hold heat. These depend upon the power of the soil to

take in warm rain and warm air, and also upon density and color. The

denser or more compact soil and the darker soil having greater power

to absorb heat.

The compactness of the soil which gives it greater powers to absorb

heat weakens its powers to hold it, because the compactness allows

more rapid conduction of heat to the surface, where it is lost by

radiation.

The more moisture a soil holds, the weaker is its heat-holding power,

because the heat is used in warming and evaporating water from the

surface of the soil.

These important properties or conditions of moisture, heat and air,

are, as we have seen, dependent on soil texture and color, which in

turn are dependent upon the relative amounts of sand, clay and humus

in the soil. We are able to control soil texture and therefore these

physical properties to a certain degree by means of tillage and the

addition of organic matter or humus (see Chapter IV).

BIOLOGICAL PROPERTIES OF A FERTILE SOIL

Biology is the story or science of life; and the biological properties

of the soil have to do with living organisms in the soil.

The soil of every fertile field is full of very small or microscopic

plants called bacteria or germs. They are said to be microscopic

because they are so small that they cannot be seen without the aid of

a powerful magnifying glass or microscope. They are so small that it

would take about 10,000 average-sized soil bacteria or soil germs

placed side by side to measure one inch.

A knowledge of three classes of these soil germs is of great

importance to the farmer. These three classes of germs are:

Nitrogen-fixing germs.

Nitrifying germs.

Denitrifying germs.

NITROGEN-FIXING GERMS

We learned in Chapter VIII that nitrogen is one of the necessary

elements of plant food, and that although the air is four-fifths

nitrogen, most plants must take their nitrogen from the soil. There

is, however, a class of plants called legumes which can use the

nitrogen of the air. Clover, alfalfa, lucern, cowpea, soy bean, snap

bean, vetch and similar plants are legumes. These legumes get the

nitrogen from the air in a very curious and interesting manner. It is

done through the aid of bacteria or germs.

Carefully dig up the roots of several legumes and wash the soil from

them. On the roots will be found many small enlargements like root

galls; these are called nodules or tubercles. On clover roots these

nodules are about the size of the head of a pin while on the soy bean

and cowpea they are nearly as large as a pea (see Fig. 34). These

nodules are filled with bacteria or germs and these germs have the

power of taking nitrogen from the air which finds its way into the

soil. After using the nitrogen the germ gives it to the plant which

then uses it to build stem, leaves and roots. In this way the legumes

are able to make use of the nitrogen of the soil air, and these germs

which help them to do it by catching the nitrogen are called

nitrogen-fixing germs.

The work of these germs makes it possible for the farmer to grow

nitrogen, so to speak, on the farm.

By growing crops of legumes and turning them under to decay in the

soil, or leaving the roots and stubble to decay after the crop is

harvested, he can furnish the following crop with a supply of nitrogen

in a very cheap manner and lessen the necessity of buying fertilizer.

NITRIFYING GERMS

Almost all the nitrogen of the soil is locked up in the humus and

cannot in that condition be used by the roots of plants. The nitrogen

caught by the nitrogen-fixing germs and built into the structure of

leguminous plants which are grown and turned under to feed other

plants cannot be used until the humus, which is produced by their

partial decay, is broken down and the nitrogen built into other

substances upon which the root can feed. The breaking down of the

humus and building of the nitrogen into other substances is the work

of another set of bacteria or germs called nitrifying germs.

These nitrifying germs attack the humus, break it down, separate the

nitrogen, cause it to unite with the oxygen of the air and thus build

it into nitric acid which can be used by plant roots. This nitric acid

if not immediately used will unite with lime or potash or soda or

other similar substances and form nitrates, as nitrate of lime,

nitrate of potash or common saltpetre. These nitrates are soluble in

water and can be easily used by plant roots. If there are no plant

roots to use them they are easily lost by being washed out of the

soil. The work of the nitrifying germs is called nitrification.

To do their work well the nitrogen-fixing germs and the nitrifying

germs require certain conditions.

The soil must be moist.

The soil must be well ventilated to supply nitrogen for the

nitrogen-fixing germs and oxygen for the nitrifying germs.

The soil must be warm. Summer temperature is the most favorable. Their

work begins and continues slowly at a temperature of about forty-five

degrees and increases in rapidity as the temperature rises until it

reaches ninety or ninety-five.

The nitrifying germs require phosphoric acid, potash and lime in the

soil.

Direct sunlight destroys these bacteria, therefore they cannot work at

the surface of the soil unless it is shaded by a crop.

From this we see that these bacteria or germs work best in the soil

that has conditions necessary for the growth and development of plant

roots.

DENITRIFYING GERMS

These germs live on the coarse organic matter of the soil. Like the

nitrifying germs they need oxygen, and when they cannot get it more

readily elsewhere they take it from the nitric acid and nitrates. This

allows the nitrogen of the nitrates to escape as a free gas into the

air again, and the work of the nitrogen-fixing and nitrifying germs is

undone and the nitrogen is lost. This loss of nitrogen is most apt to

occur when the soil is poorly ventilated, because of its being very

compact, or when the soil spaces are filled with water. This loss of

nitrogen by denitrification can be checked by keeping the soil well

ventilated.

CHEMICAL PROPERTIES OF A FERTILE SOIL

By the term chemical properties we have reference to the chemical

which help them to do it by catching the nitrogen are called

nitrogen-fixing germs.

The work of these germs makes it possible for the farmer to grow

nitrogen, so to speak, on the farm.

By growing crops of legumes and turning them under to decay in the

soil, or leaving the roots and stubble to decay after the crop is

harvested, he can furnish the following crop with a supply of nitrogen

in a very cheap manner and lessen the necessity of buying fertilizer.

NITRIFYING GERMS

Almost all the nitrogen of the soil is locked up in the humus and

cannot in that condition be used by the roots of plants. The nitrogen

caught by the nitrogen-fixing germs and built into the structure of

leguminous plants which are grown and turned under to feed other

plants cannot be used until the humus, which is produced by their

partial decay, is broken down and the nitrogen built into other

substances upon which the root can feed. The breaking down of the

humus and building of the nitrogen into other substances is the work

of another set of bacteria or germs called nitrifying germs.

These nitrifying germs attack the humus, break it down, separate the

nitrogen, cause it to unite with the oxygen of the air and thus build

it into nitric acid which can be used by plant roots. This nitric acid

if not immediately used will unite with lime or potash or soda or

other similar substances and form nitrates, as nitrate of lime,

nitrate of potash or common saltpetre. These nitrates are soluble in

water and can be easily used by plant roots. If there are no plant

roots to use them they are easily lost by being washed out of the

soil. The work of the nitrifying germs is called nitrification.

To do their work well the nitrogen-fixing germs and the nitrifying

germs require certain conditions.

The soil must be moist.

The soil must be well ventilated to supply nitrogen for the

nitrogen-fixing germs and oxygen for the nitrifying germs.

The soil must be warm. Summer temperature is the most favorable. Their

work begins and continues slowly at a temperature of about forty-five

degrees and increases in rapidity as the temperature rises until it

reaches ninety or ninety-five.

The nitrifying germs require phosphoric acid, potash and lime in the

soil.

Direct sunlight destroys these bacteria, therefore they cannot work at

the surface of the soil unless it is shaded by a crop.

From this we see that these bacteria or germs work best in the soil

that has conditions necessary for the growth and development of plant

roots.

DENITRIFYING GERMS

These germs live on the coarse organic matter of the soil. Like the

nitrifying germs they need oxygen, and when they cannot get it more

readily elsewhere they take it from the nitric acid and nitrates. This

allows the nitrogen of the nitrates to escape as a free gas into the

air again, and the work of the nitrogen-fixing and nitrifying germs is

undone and the nitrogen is lost. This loss of nitrogen is most apt to

occur when the soil is poorly ventilated, because of its being very

compact, or when the soil spaces are filled with water. This loss of

nitrogen by denitrification can be checked by keeping the soil well

ventilated.

CHEMICAL PROPERTIES OF A FERTILE SOIL

By the term chemical properties we have reference to the chemical

composition of the soil, the chemical changes which take place in the

soil, and the conditions which influence these changes.

The sand, clay and humus of the soil are made up of a great variety of

substances. The larger part of these act simply as a mechanical

support for the plants and also serve to bring about certain physical

conditions. Only a very small portion of these substances serve as the

direct food of plants and the chemical conditions of these substances

are of great importance.

In Chapter VIII we learned that plants are composed of several

elements and that seven necessary elements are taken from the soil.

These seven are nitrogen, phosphorus, potassium, magnesium, calcium,

iron and sulphur.

Now a fertile soil must contain these seven elements of plant food and

they must be in such form that the plant roots can use them.

Plant roots can generally get from most soils enough of the magnesium,

calcium, iron, and sulphur to produce well developed plants. But the

nitrogen, phosphorus and potassium, although they exist in sufficient

quantities in the soil, are often in such a form or condition that the

roots cannot get enough of one or more of them to produce profitable

crops. For this reason these three elements are of particular

importance to the farmer for, in order to keep his soil fertile, he

must so treat it that these elements will be made available or he must

add more of them to the soil in the proper form or condition.

_Nitrogen in the soil._–Plant roots use nitrogen in the form of

nitric acid and salts of nitrogen called nitrates. But the nitrogen of

the soil is very largely found in the humus with the roots cannot use.

A chemical change must take place in it and the nitrogen be built into

nitric acid and nitrates. This, we have learned, is done through the

aid of the nitrifying germs.

_Phosphoric acid in the soil._–Phosphorus does not exist pure in the

soil. The plant finds it as a phosphoric acid united with the other

substances forming phosphates. These are often not available to

plants, but can to a certain extent be made available through tillage

and by adding humus to the soil.

_Potash in the soil._–The plant finds potassium in potash which

exists in the soil. Potash like phosphoric acid often exists in forms

which the plant cannot use but may be made available to a certain

extent by tillage, the addition of humus, and the addition of lime to

the soil.

_Lime in the soil._–Most soils contain the element calcium or lime,

the compound in which it is found, in sufficient quantities for plant

food. But lime is also of importance to the farmer and plant grower

because it is helpful in causing chemical changes in the soil which

tend to prepare the nitrogen, phosphoric acid and potash for plant

use. It is also helpful in changing soil texture.

The chemical changes which make the plant foods available are

dependent on moisture, heat, and air with its oxygen, and are

therefore dependent largely on texture, and therefore on tillage.

When good tillage and the addition of organic matter and lime do not

render available sufficient plant food, then the supply of available

food may be increased by the application of manure and fertilizers.

It will be seen that all these classes of properties are necessary to

furnish all the conditions for root growth.

The proper chemical conditions require the presence of both physical

and biological properties and the biological work in the soil

requires both chemical and physical conditions.

From the farmer’s standpoint the physical properties seem to be most

important, for the others are dependent on the proper texture,

moisture, heat and ventilation which are controlled largely by

tillage.

Therefore the first effort of the farmer to improve the fertility of

composition of the soil, the chemical changes which take place in the

soil, and the conditions which influence these changes.

The sand, clay and humus of the soil are made up of a great variety of

substances. The larger part of these act simply as a mechanical

support for the plants and also serve to bring about certain physical

conditions. Only a very small portion of these substances serve as the

direct food of plants and the chemical conditions of these substances

are of great importance.

In Chapter VIII we learned that plants are composed of several

elements and that seven necessary elements are taken from the soil.

These seven are nitrogen, phosphorus, potassium, magnesium, calcium,

iron and sulphur.

Now a fertile soil must contain these seven elements of plant food and

they must be in such form that the plant roots can use them.

Plant roots can generally get from most soils enough of the magnesium,

calcium, iron, and sulphur to produce well developed plants. But the

nitrogen, phosphorus and potassium, although they exist in sufficient

quantities in the soil, are often in such a form or condition that the

roots cannot get enough of one or more of them to produce profitable

crops. For this reason these three elements are of particular

importance to the farmer for, in order to keep his soil fertile, he

must so treat it that these elements will be made available or he must

add more of them to the soil in the proper form or condition.

_Nitrogen in the soil._–Plant roots use nitrogen in the form of

nitric acid and salts of nitrogen called nitrates. But the nitrogen of

the soil is very largely found in the humus with the roots cannot use.

A chemical change must take place in it and the nitrogen be built into

nitric acid and nitrates. This, we have learned, is done through the

aid of the nitrifying germs.

_Phosphoric acid in the soil._–Phosphorus does not exist pure in the

soil. The plant finds it as a phosphoric acid united with the other

substances forming phosphates. These are often not available to

plants, but can to a certain extent be made available through tillage

and by adding humus to the soil.

_Potash in the soil._–The plant finds potassium in potash which

exists in the soil. Potash like phosphoric acid often exists in forms

which the plant cannot use but may be made available to a certain

extent by tillage, the addition of humus, and the addition of lime to

the soil.

_Lime in the soil._–Most soils contain the element calcium or lime,

the compound in which it is found, in sufficient quantities for plant

food. But lime is also of importance to the farmer and plant grower

because it is helpful in causing chemical changes in the soil which

tend to prepare the nitrogen, phosphoric acid and potash for plant

use. It is also helpful in changing soil texture.

The chemical changes which make the plant foods available are

dependent on moisture, heat, and air with its oxygen, and are

therefore dependent largely on texture, and therefore on tillage.

When good tillage and the addition of organic matter and lime do not

render available sufficient plant food, then the supply of available

food may be increased by the application of manure and fertilizers.

It will be seen that all these classes of properties are necessary to

furnish all the conditions for root growth.

The proper chemical conditions require the presence of both physical

and biological properties and the biological work in the soil

requires both chemical and physical conditions.

From the farmer’s standpoint the physical properties seem to be most

important, for the others are dependent on the proper texture,

moisture, heat and ventilation which are controlled largely by

tillage.

Therefore the first effort of the farmer to improve the fertility of

his soil should be to improve his methods of working the soil.

Every one of these properties of the fertile soil, and consequently

every one of the conditions necessary for the growth and development

of plant roots, is influenced in some way by every operation performed

on the soil, whether it be plowing, harrowing, cultivating, applying

manure, growing crops, harvesting, or anything else, and the

thoughtful farmer will frequently ask himself the question: “How is

this going to effect the fertility of my soil or the conditions

necessary for profitable crop production?”

MAINTENANCE OF FERTILITY

The important factors in maintaining or increasing the fertility of

the soil are:

The mechanical operations of tillage, especially with reference to the

control of soil water.

The application of manures and fertilizers, especially with reference

to maintaining a supply of humus and plant food.

Methods or systems of cropping the soil, with reference to economizing

fertility.

CHAPTER XVII

SOIL WATER

The more important tillage tools and tillage operations we studied in

Chapters XI and XII. They will be noticed here only in connection with

their influence over soil water, for in the regulation of this

important factor in soil fertility the other conditions of fertility

are also very largely controlled.

IMPORTANCE OF SOIL WATER

“Of all the factors influencing the growth of plants, water is beyond

doubt the most important,” and the maintaining of the proper amount of

soil water is one of the most important problems of the thinking

farmer in controlling the fertility of his soil.

NECESSITY OF SOIL WATER

The decay of mineral and organic matter in the soil, and the

consequent setting free of plant food, can take place only in the

presence of moisture. The plant food in barn manures and crops plowed

under for green moisture, can be made available only when there is

sufficient moisture in the soil to permit breaking down and

decomposition.

The presence of moisture in the soil is necessary for the process of

nitrification to take place.

Soil moisture is necessary to dissolve plant food. Plant roots can

absorb food from the soil only when it is in solution, and it seems to

be necessary that a large quantity of water pass through the plant

tissues to furnish the supply of mineral elements required by growth.

Moisture is necessary to build plant tissues. The quantity of water

entering into the structure of growing plants varies from sixty to as

high as ninety-five per cent, of their total weight.

During the periods of active growth there is a constant giving off of

moisture by the foliage of plants and this must be made good by water

taken from the soil by their roots.

In a series of experiments at the University of Wisconsin Agricultural