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.



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.

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 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 Experiment Station, it was found that in raising oats, every ton of dry matter grown required 522.4 tons of water to produce it; for every ton of dry matter of corn there were required 309.8 tons of water; a ton of dry red clover requires 452.8 tons of water to grow it. At the Cornell University Agricultural Experiment Station, a yield of potatoes at the rate of 450 bushels per acre represented a water requirement of 1310.75 tons of water.

SOURCES AND FORMS OF SOIL WATER

The soil which is occupied by the roots of plants receives moisture in the form of rain, snow and dew from above and free and capillary water rising from below.

"Free water is that form of water which fills our wells, is found in the bottom of holes dug in the ground during wet seasons, and is often found standing on the surface of the soil after heavy or long continued rains. It is sometimes called 'ground water' or 'standing water,' and flows under the influence of gravity." Free water is not used directly by plants unless they are swamp plants, and its presence within eighteen inches of the surface is injurious to most farm plants. Free water serves as the main source of supply for capillary water.

"Capillary water is water which is drawn by capillary force or soaks into the spaces between the soil particles and covers these particles with a thin film of moisture." It is a direct source of water to plants. Capillary water will flow in any direction in the soil, the direction of flow being determined by texture and dryness, the flow being stronger toward the more compact and drier parts. If the soil is left lumpy and cloddy then capillary water cannot rise readily from below to take the place of that which is lost by evaporation. If, however, the soil is fine and well pulverized, the water rises freely and continuously to supply the place of that taken by plant roots or evaporation from the surface.

TOO MUCH WATER

Some farm lands contain too much water for the growth of farm crops; for example, bottom lands which are so low that water falling on the surface cannot run off or soak down into the lower soil. The result is that the spaces between the soil particles are most of the time filled with water, and this checks ventilation, which is a necessary factor in soil fertility. This state of affairs occurs also on sloping uplands which are kept wet by spring water or by seepage water from higher lands. Some soils are so close and compact that water falling on the surface finds great difficulty in percolating through them, and therefore renders them too wet for profitable cropping during longer or shorter periods of the year. Nearly all such lands can be improved by removing the surplus water through drains. (See Chapter XXV.)

Percolation and ventilation of close compact soils can be improved by mixing lime and organic matter with them.

NOT ENOUGH WATER

In some sections of the country, particularly the arid and semi-arid sections of the West, the soil does not receive a sufficient supply of rain water for the production of profitable yearly crops. These soils are rendered unfertile by the lack of this one all important factor of fertility. They can be made fertile and productive by supplying them with sufficient water through irrigation.

The crop-producing power of some lands is lowered even in regions where the rainfall is sufficient, because these lands are not properly prepared by tillage and the addition of organic matter to absorb and hold the water that comes to them, or part of the water may be lost or wasted by lack of proper after-tillage or after-cultivation. This state of affairs is of course improved by better preparation to receive water before planting the crop and better methods of after-cultivation to save the water for the use of the crop.

LOSS OF SOIL WATER

Aside from what is used by the crops the soil may lose its water in the following ways:

Rain water which comes to the soil may be lost by running off over the surface of the land. This occurs especially on hilly farms and in the case of close, compact soils.

Water may be lost from the soil by leaching through the lower soil.

Water may be lost from the soil by evaporation from the surface.

The soil may lose water by the growth of weeds which are continually pumping water up by their roots and transpiring it from their leaves into the air.

HOW SOME FARM OPERATIONS INFLUENCE SOIL WATER

Plowing and soil water. One of the first effects of deeply and thoroughly plowing a close, compact soil, is that rain will sink into it readily and not be lost by surface wash. In many parts of the country, especially the South, great damage is done by the surface washing and gulleying of sloping fields.

The shallow layer of soil stirred up by small plows and practice of shallow plowing so prevalent in the South takes in the rain readily, but as the harder soil beneath does not easily absorb the water the shallow layer of plowed soil soon fills, then becomes mud, and the whole mass goes down the slope. Where the land is plowed deep there is prepared a deep reservoir of loose soil that is able to hold a large amount of water till the harder lower soil can gradually absorb it.

The soil stirred and thoroughly broken by the plow serves not only as a reservoir for the rainfall, but also acts as a mulch over the more compact soil below it, thus checking the rapid use of capillary water to the surface and its consequent loss by evaporation. The plow which breaks and pulverizes the soil most thoroughly is the one best adapted to fit the soil for receiving and holding moisture.

If the plowing is not well done or if the land is too dry when plowed and the soil is left in great coarse lumps and clods, the air circulates readily among the clods and takes from them what little moisture they may have had and generally the soil is left in a worse condition than if it had not been plowed at all.

Fall plowing on rolling land and heavy soil leaving the surface rough helps to hold winter snows and rains when they fall, giving to such fields a more even distribution of soil water in the spring.

Spring plowing should be done early, before there is much loss of water from the surface by evaporation.

Professor King, of the University of Wisconsin Agricultural Experiment Station, carried on an experiment to see how much soil water could be saved by early plowing. He selected two similar pieces of ground near each other and tested them for water April 29th. Immediately after testing one piece was plowed. Seven days later, May 6th, he tested them for water again and found that both had lost some water, but that the piece which was not plowed had lost 9.13 pounds more water per square foot of surface than the plowed piece. This means that by plowing one part a week earlier than the other he saved in it water equal to a rainfall of nearly two inches or at the rate of nearly 200 tons of water per acre.

HOEING, RAKING, HARROWING, AND CULTIVATING

These operations when properly and thoroughly done tend to supplement the work of the plow in fitting the soil to absorb rain and in making a mulch to check loss by surface evaporation. The entire surface should be worked and the soil should be left smooth and not in ridges. Rolling cutters and spring-toothed harrows are apt to leave ridges and should have an attachment for smoothing the surface or be followed by a smoothing harrow. Cultivators used to make mulches to save water should have many narrow teeth rather than few broad ones. If a large broad-toothed tool is used to destroy grass and large weeds it should be followed by a smoother to level the ridges and thus lessen the evaporating surface. The soil should be cultivated as soon after a rain as it can be safely worked.

Rolling compacts the soil and starts a quicker capillary movement of water toward the surface and a consequent loss by evaporation. When circumstances will permit, the roller should be followed by a light harrow to restore the mulch.

Ridging the land tends to lessen the amount of moisture in the soil because it increases the evaporating surface. It should be practiced only on wet land or in early spring to secure greater heat.

Drains placed in wet land remove free water to a lower depth and increase the depth of soil occupied by capillary water and therefore increase the body of soil available to plant roots.

MANURES AND SOIL WATER

Humus, as we learned in Chapter IV, has a very great and therefore important influence over the water-absorbing and water-holding powers of soils. Therefore, any of the farm practices that tend to increase or diminish the amount of humus in the soil are to be seriously considered because of the effect on the water content of the soil. For this reason the application of barn manures and green crops turned under tend to improve the water conditions of most soils.

The mixing of heavy applications of coarse manures or organic matter with light sandy soils may make them so loose and open that they will lose moisture rapidly. When this practice is necessary the land should be rolled after the application of the manure.

METHODS OF CROPPING AND SOIL WATER

Constant tillage hastens the decay of organic matter in the soil. Hence any method or system of cropping which does not occasionally return to the soil a new supply of humus tends to weaken the powers of the soil toward water.

All of the operations and practices which influence soil water also affect the other conditions necessary to root growth; namely, texture, ventilation, heat, and plant food, and those operations and practices which properly control and regulate soil water to a large degree control and regulate soil fertility.

SELECTION OF CROPS WITH REFERENCE TO SOIL WATER

While climatic conditions determine the general distribution of plants, the amount of water which a soil holds and can give up to plants during the growing season determines very largely the crops to which it is locally best adapted.

With crops that can be grown on a wide range of soils the water which the soil can furnish largely determines the time of maturing, the yield, and often the quality of the crop. With such a crop a small supply of water tends to hasten maturity at the expense of yield.

The sweet potato, when wanted for early market and high prices, is grown on the light sandy soils called early truck soils. These soils hold from five to seven per cent, of water. That is, the texture is such that during the early part of the growing season one hundred pounds of this soil is found to hold an average of from five to seven pounds of water under field conditions. This soil, holding little water, warms up early and thus hastens growth. Then as the warmer summer weather advances, the water supply diminishes, growth is checked, and the crop matures rapidly. On account of the small amount of water and the early checking of growth, the yield of the crop is less than if grown on a soil holding more water, but the earlier maturity makes it possible to realize a much higher price per bushel for the crop. A sweet potato grown on such a light soil is dry and starchy, a quality which brings a higher price in the northern markets than does the moist, soggy potato grown on heavier soils which contain more water and produce larger yields.

Early white potatoes, early cabbage, water melons, musk-melons, tomatoes and other early truck and market garden crops are also grown on light soil holding from five to seven per cent. of water. The main crop of potatoes and cabbage and the canning crop of tomatoes are grown on the loam soils holding from ten to eighteen per cent. of water. Such soils produce a later though much larger yield.

Upland cotton produces best on a deep loam that is capable of furnishing a uniform supply of about ten or twelve per cent. of water during the growing season.

Sea Island Cotton grows best on a light, sandy soil holding only five per cent. of water.

On light, sandy soils the Upland Cotton produces small plants with small yield of lint, while on clay and bottom land, which are apt to have large amounts of water, the plants grow very large and produce fewer bolls, which are very late in maturing.

Corn, while it will grow on a wide range of soils, produces best on loam or moist bottom lands holding about fifteen per cent. of water during the growing season.

The grasses and small grains do best on cool, firm soils holding eighteen to twenty-two per cent. of water.

Sorghum or "Molasses Cane" grows best on good corn soil, while the sugar cane of the Gulf States requires a soil with twenty-five per cent. of water for best growth.

While the amount of water which a soil will hold is determined largely by texture, it is also considerably influenced by the amount and frequency of rainfall and the location of the soil as to whether it be upland or bottom land.

The average percentage of water held by a soil during the growing season may be approximately determined in the following manner:

Sample the soil in one of the following methods:

Take to the field a spade, a box that will hold about half a bushel, and a pint or quart glass jar with a tight cover. If a cultivated field, select a place free from grass and weeds. Dig a hole one foot deep and about eighteen inches square. Trim one side of the hole square. Now from this side cut a slice about three inches thick and one foot deep, quickly place this in the box and thoroughly break lumps and mix together, then fill jar and cork tightly.

Another method is to take a common half-inch or two-inch carpenter's auger and bore into the soil with it. Pull it out frequently and put the soil which comes up with it into the jar until you have a sample a foot deep. If one boring twelve inches deep does not give sufficient soil make another boring or two close by and put all into the jar.

Take the sample, by whatever method obtained, weigh out ten or twenty ounces of the moist soil and dry it at a temperature just below 212 degrees. When it is thoroughly dry weigh again. The difference between the two weights will be the amount of water held by the sample. Now divide this by the weight of the dry sample and the result will be the per cent. of water held by the soil.

Several samples taken from different parts of the field will give an average for the field. Repeat this every week or oftener through the season and an approximate estimate of the water-holding capacity of the soil will be obtained and consequently an indication of the crops to which the soil is best adapted.

EXAMPLE. Weight of a soil sample, 20 ounces. When dried this sample weighs 173/4 ounces. 20 - 173/4 = 21/4, the water held by the soil. 2.25 / 17.75 = .12 plus.

This soil held a little over twelve per cent. of water. If this soil continues to give about the same result for successive tests during the growing season, the results would indicate a soil adapted to cotton, late truck or corn.



CHAPTER XVIII

THE AFTER-CULTIVATION OF CROPS

The term "after-cultivation" is here used in referring to those tillage operations which are performed after the crop is planted. Synonymous terms are "cultivation," "inter-tillage," "working the crop."

After-cultivation influences the texture, ventilation, heat, plant food and moisture factors of fertility, but most particularly the moisture factor.

Under ordinary circumstances the greatest benefit derived from after-cultivation when properly performed is the saving of soil water for the use of the crop.

LOSS OF WATER BY EVAPORATION

Soil water is seldom at rest unless the soil be frozen solid. When rain falls on a fertile soil there is a downward movement of water. When the rain ceases, water begins to evaporate from the surface of the soil. Its place is taken by water brought from below by capillarity. This is in turn evaporated and replaced by more from below. This process continues with greater or less rapidity according to the dryness of the air and the compactness of the soil.

LOSS OF WATER THROUGH WEEDS

We learned in a former chapter that during their growth farm plants require an amount of water equal to from 300 to 500 times their dry weight. Weeds require just as much water and some of them probably more than the cultivated plants. This water is largely absorbed by the roots and sent up to the leaves where it is transpired into the air and is lost from the soil, and therefore is unavailable to the growing crop until it again falls onto the soil.

In some parts of the country, particularly the semi-arid West, the rainfall is not sufficient to supply the soil with enough water to grow such crops as it could otherwise produce. In the moister regions the rainfall is not evenly distributed throughout the growing season, and there are longer or shorter intervals between rains when the loss of water through evaporation and weeds is apt to be greater than the rainfall. For these reasons it is best to check these losses and save the water in the soil for the use of the crops.

SAVING THE WATER

This can be done by:

Preventing the growth of weeds and by checking losses by evaporation with a soil mulch.

TIME TO CULTIVATE

A seedling plant is easiest killed just as it has started into growth. The best time to kill a plant starting from an underground stem or a root is just as soon as it appears above the surface in active growth.

The best time to cultivate, then, to kill weeds is as soon as the weeds appear. At this time large numbers can be killed with the least of effort. Do not let them get to be a week or two old before getting after them.

In planting some crops the ground between the rows becomes trampled and compact. This results in active capillarity which brings water to the surface and it is lost by evaporation.

Every rainfall tends to beat the soil particles together and form a crust which enables the capillary water to climb to the surface and escape into the air. This loss by evaporation should be constantly watched for and the soil should be stirred and a mulch formed whenever it becomes compact or a crust is formed.

The proper time to cultivate, then, to save water is as soon as weeds appear or as soon as the surface of the soil becomes compact or crusted by trampling, by the beating of rain or from any other cause, whether the crop is up or not. The cultivation should start as soon after a rain as the soil is dry enough to work safely.

The surface soil should always be kept loose and open. The efficacy of the soil mulch depends on the thoroughness and frequency of the operation. It is particularly beneficial during long, dry periods. During such times it is not necessary to wait for a rain to compact the soil; keep the cultivators going, rain or no rain.

TOOLS FOR AFTER-CULTIVATION

The main objects of after-cultivation are to destroy weeds and to form a soil mulch for the purpose of controlling soil moisture. These ends are secured by shallow surface work. It is not necessary to go more than two or three inches deep. Deeper work will injure the roots of the crop. Therefore the proper tools for after-cultivation in the garden are the hoe and rake and for field work narrow-toothed harrows and cultivators or horse-hoes which stir the whole surface thoroughly to a moderate depth. These field tools are supplemented in some cases by the hand hoe, but over wide areas of country the hoe never enters the field.

A light spike-toothed harrow can be used on corn, potatoes, and similar crops, and accomplish the work of cultivation rapidly until they get to be from four to six inches high; after that cultivators which work between the rows should be used.

A very useful class of tools for destroying weeds in the earlier stages are the so-called "weeders." They somewhat resemble a horse hay rake and have a number of flexible wire teeth which destroy shallow rooted weeds but slip around the more firmly rooted plants of the crop. These weeders must be used frequently to be of much value, for after a weed is well rooted the weeder cannot destroy it.

There is a larger class of hand wheel hoes which are very useful in working close planted garden and truck crops. They either straddle the row, working the soil on both sides at the same time, or, running between the rows, work the soil to a width of from six to eighteen inches.

For best results with the weeder and hand wheel hoes the soil should be thoroughly prepared before planting by burying all trash with the plow and breaking all clods with harrow and roller.

The objection made to the deep-working implements, like the plow, is that they injure the crop by cutting its feeding roots, and this has been found by careful experiment and observation to diminish the crop.

Some farmers object to using a light harrow for cultivation in the early stages of the crop because they say the harrow will destroy the crop as well as the weeds. This danger is not so great as it seems. The seeds of the crop are deeper in the soil than the seeds of the weeds which germinate and appear so quickly. The soil has also been firmed about them. Hence they have a firmer hold on the soil and but few of them are destroyed if the work is carefully done.

In working crops not only should weeds be destroyed but also surplus plants of the crop, as these have the same effect as weeds; namely, they occupy the soil and take plant food and moisture which if left to fewer plants would produce a larger harvest.

HILLING AND RIDGING

Except in low, wet ground, the practice of hilling or ridging up crops is now considered by those who have given the matter thorough study, to be unnecessary, flat and shallow culture being cheaper. It saves more moisture, and for this reason, in the majority of cases, produces larger crops.

Sometimes during very long-continued periods of wet weather weeds and grass become firmly established among the plants of the crop. Under such circumstances it is necessary to use on the cultivator teeth having long, narrow sweeps that will cut the weeds just beneath the surface of the soil. Sometimes a broad-toothed tool is used that will throw sufficient soil over the large weeds near the rows to smother them.

The condition to be met and the effect of the operation should always be given serious thought.

We have considered after-cultivation as influencing soil fertility by checking a loss of water by evaporation and weed transpiration, and this is its main influence but other benefits follow.

Keeping the surface soil loose and open benefits fertility because it directly aids the absorption of rain, favors ventilation, and has a beneficial influence over soil temperature. Indirectly through these factors it aids the work of the beneficial soil bacteria and the chemical changes in the process of preparing plant food for crop use.



CHAPTER XIX

FARM MANURES

FUNCTIONS OF MANURES AND FERTILIZERS

In Chapter II we learned that the roots of plants for their growth and development need a soil that is firm yet mellow, moist, warm, ventilated and supplied with plant food. We also learned that of the plant foods there is often not enough available nitrogen, phosphoric acid, potash and lime for the needs of the growing plants.

Manures and fertilizers are applied to the soil for their beneficial effects on these necessary conditions for root growth and therefore to assist in maintaining soil fertility.

CLASSIFICATION OF MANURES AND FERTILIZERS

Manures may be classified as follows:

{ Barn or stable manures, Farm manures. { Green-crop manures, { Composts.

Commercial { Materials furnishing nitrogen, fertilizers { " " phosphoric acid, or artificial { " " potash, manures. { " " lime.

IMPORTANCE OF FARM MANURES

Of these two classes of manures the farmer should rely chiefly on the farm manures letting the commercial fertilizers take a secondary place because:

Farm manures are complete manures; that is they contain all the necessary elements of plant food.

Farm manures add to the soil large amounts of organic matter or humus.

The decay of organic matter produces carbonic acid which hastens the decay of mineral matter in the soil and so increases the amount of available plant food.

The organic matter changes the texture of the soil.

It makes sandy soils more compact and therefore more powerful to hold water and plant food.

It makes heavy clay soils more open and porous, giving them greater power to absorb moisture and plant food. This admits also of better circulation of the air in the soil, and prevents baking in dry weather.

Farm manures influence all of the conditions necessary for root growth while the commercial fertilizers influence mainly the plant food conditions.

The farm manures are good for all soils and crops.

They are lasting in their effects on the soil.

BARN OR STABLE MANURE

Barn or stable manure consists of the solid and liquid excrement of any of the farm animals mixed with the straw or other materials used as bedding for the comfort of the animals and to absorb the liquid parts.

The liquid parts should be saved, as they contain more than half of the nitrogen and potash in the manure.

The value of barn manure for improving the soil conditions necessary for root growth depends in a measure upon the plant food in it, but chiefly upon the very large proportion of organic matter which it contains when it is applied to the soil.

These factors are influenced somewhat: by the kind of animal that produces the manure; by the kind of food the animal receives; by the kind and amount of litter or bedding used; but they depend particularly on the way the manure is cared for after it is produced.

LOSS OF VALUE

Improper care of the manure may cause it to diminish in value very much.

Loss by leaching.

If the manure is piled against the side of the stable where water from the roof can drip on it, as is often the case, or if it is piled in an exposed place where heavy rain can beat on it, the rain water in leaching through the manure washes out of it nitrogen and potash, which pass off in the dark brown liquid that oozes from the base of the pile.

Loss by heating or fermenting.

When barn manure is thrown into piles it soon heats and throws off more or less steam and gas. This heating of the manure is caused by fermentation or the breaking down of the materials composing the manure and the forming of new compounds. This fermentation is produced by very small or microscopic plants called bacteria.

The fermentation of the manure is influenced by the following conditions:

A certain amount of heat is necessary to start the work of the bacteria. After they have once started they keep up and increase the temperature of the pile until it gets so hot that sometimes a part of the manure is reduced to ashes. The higher the temperature the more rapid the fermentation. This can be seen particularly in piles of horse manure.

The bacteria which produce the most rapid fermentation in manure need plenty of air with its oxygen. Therefore fermentation will be more or less rapid according as the manure is piled loosely or in a close compact mass.

A certain amount of moisture is necessary for the fermentation to take place, but if the manure is made quite wet the temperature is lowered and the fermentation is checked. The water also checks the fermentation by limiting the supply of air that can enter the pile.

The composition of the manure influences the fermentation. The presence of considerable amounts of soluble nitrogen hastens the rapidity of the fermentation.

Now when the manure ferments a large part of the organic matter in it is broken down and changed into gases. The gas formed most abundantly by the fermentation is carbonic acid gas, which is produced by the union of oxygen with carbon of the organic matter. The formation of this gas means a loss of humus. This loss can be noticed by the fact that the pile gradually becomes smaller.

The next most abundant product of the fermentation is water vapor which can often be seen passing off in clouds of steam.

When manure ferments rapidly the nitrogen in it is changed largely into ammonia. This ammonia combines with part of the carbonic acid gas and forms carbonate of ammonia, a very volatile salt which rapidly changes to a vapor and is lost in the atmosphere. This causes a great loss of nitrogen during the rapid decomposition of the manure. This loss can be detected by the well known odor of the ammonia which is particularly noticeable about horse stables and piles of horse manure.

Besides these gases a number of compounds of nitrogen, potash, etc., are formed which are soluble in water. It is these that form the dark brown liquid that sometimes oozes out from the base of the manure heap.

At the Cornell University Agricultural Experiment Station, the following experiment was carried out to find out how much loss would take place from a pile of manure:

"Four thousand pounds of manure from the horse stable were placed out of doors in a compact pile and left exposed from April 25th to September 22d. The results were as follows:"

+ -+ + April 25. Sept. 22. Loss per cent. + -+ + Gross weight 4,000 lbs. 1,730 lbs. 57 Nitrogen 19.6 " 7.79 " 60 Phos. acid 14.8 " 7.79 " 47 Potash 36 " 8.65 " 76 Value of plant food per ton $2.30 $1.06 + -+ +

This shows a loss of more than half the bulk of the manure and more than half the plant food contained in it.

CHECKING THE LOSSES

The first step to be taken in preserving the manure or in checking losses is to provide sufficient bedding or litter in the stable to absorb and save all the liquid parts.

The losses from fermentation of hot manures like horse manure may be largely checked by mixing with the colder manure from the cow stable.

Losses from fermentation may also be checked.

By piling compactly, which keeps the air out.

By moistening the pile, which lowers the temperature and checks the access of oxygen.

The manure may be hauled directly to the field each day and spread on the surface or plowed in. This method is the best when practicable because fermentation of the manure will take place slowly in the soil and the gases produced will be absorbed and retained by the soil.

Gypsum or land plaster is often sprinkled on stable floors and about manure heaps to prevent the loss of ammonia.

Copperas or blue stone, kainite and superphosphate are sometimes used for the same purpose. There is, however, nothing better nor so good for this purpose as dry earth containing a large percentage of humus.

Losses from washing or leaching by rain may be prevented by piling the manure under cover or by hauling it to the field as soon as produced and spreading it on the surface or plowing it under.

APPLYING THE MANURE TO THE SOIL

From ten to twenty tons per acre is considered a sufficient application of barn manure for most farm crops. Larger amounts are sometimes applied to the soil for truck and market garden crops.

Barn manures are applied to the soil by these methods:

The manure is sometimes hauled out from the barn and placed in a large pile in the field or in many small piles where it remains for some time before being spread and plowed or harrowed in.

Some farmers spread it on the field and allow it to lie some time before plowing it in.

It is sometimes spread as soon as hauled to the field and is immediately plowed in or mixed with the soil. This last is the safest and most economical method so far as the manure alone is concerned.

When the manure is left in a large pile it suffers losses due to fermentation and leaching.

At the Cornell University Agricultural Experiment Station, five tons of manure from the cow stable, including three hundred pounds of gypsum which was mixed with it, were exposed in a compact pile out of doors from April 25th to September 22d. The result was as follows:

+ -+ -+ April 25 Sept 22 Loss per cent. + -+ -+ Gross weight 10,000 lbs. 5,125 lbs. 49 Nitrogen 47 " 28 " 41 Phos. acid 32 " 26 " 19 Potash 48 " 44 " 8 Value of plant food per ton $2.29 $1.60 + -+ -+

When distributed over the field in small piles and allowed to remain so for some time, losses from fermentation take place, and the rain washes plant food from the pile into the soil under and immediately about it. This results in an uneven distribution of plant food over the field, for when the manure is finally scattered and plowed in, part of the field is fertilized with washed out manure while the soil under and immediately about the location of the various piles is often so strongly fertilized that nothing can grow there unless it be rank, coarse weeds.



When the manure is spread on the surface and allowed to lie for some time it is apt to become dry and hard, and when finally plowed in, decays very slowly.

When the manure is plowed in or mixed with the soil as soon as applied to the field there results an even distribution of plant food in the soil, fermentation takes place gradually and all gases formed are absorbed by the soil, there is very little loss of valuable nitrogen and organic matter, and the fermentation taking place in the soil also aids in breaking down the mineral constituents of the soil and making available the plant food held by them.

Therefore it seems best to spread the manure and plow it in or mix it with the soil as soon as it is hauled to the field, when not prevented by bad weather and other more pressing work.

PROPER CONDITION OF MANURE WHEN APPLIED

A large part of the value of barn manure lies in the fact that it consists largely of organic matter, and therefore has an important influence on soil texture, and during its decay in the soil produces favorable chemical changes in the soil constituents. Therefore it will produce its greatest effect on the soil when applied fresh. For this reason it is generally best to haul the manure to the field and mix it with the soil as soon after it is produced as possible.

If coarse manures are mixed with light, sandy soils it is best to follow with the roller, otherwise the coarse manure may cause the soil to lie so loose and open that both soil and manure will lose moisture so rapidly that fermentation of the manure will be stopped and the soil will be unfit for planting.

If it is desired to apply manure directly to delicate rooted truck and vegetable crops it is best to let it stand for some time until the first rank fermentation has taken place and the manure has become rotten.

A good practice is to apply the manure in its fresh condition to coarse feeding crops like corn, and then follow the corn by a more delicate rooted crop which requires the manure to be in a more decomposed condition than is necessary for the corn. In this case the corn is satisfied and the remaining manure is in proper condition for the following crop when it is planted.

Another practice is to broadcast the coarse manure on grass land and then when the hay is harvested the sod and remaining manure are plowed under for the following crop.

A study of root development in Chapter II. tells us that most of the manure used for cultivated crops should be broadcasted and thoroughly mixed with the soil. A small amount may be placed in the drill or hill and thoroughly mixed with the soil for crops that are planted in rows or furrows in order to give the young plant a rapid start. For the vegetable garden and flower garden and lawns, it is best to apply only manure that has been piled for some time and has been turned over several times so that it is well rotted and broken up.

There may not be a single farm where it will be possible to carry out to the letter these principles applying to the treatment and application of barn manures.

This is because climate, crops and conditions vary in different parts of the country and on different farms. Therefore we should study carefully our conditions and the principles and make our practice so combine the two as to produce the best and most economical results under the circumstances.

If we can get manure out in the winter it will very much lessen the rush of spring work.

In some parts of the country on account of deep snows, heavy rainfall and hilly fields, it is not advisable to apply manure in the winter. This will necessitate storing the manure.

If conditions are such that we can get the manure on to the land as soon as it is made, it should be applied to land on which a crop is growing or land which is soon to be planted. If land is not intended for an immediate crop, put a cover crop on it.

COMPOSTS

Composts are collections of farm trash or rubbish, as leaves, potato tops, weeds, road and ditch scrapings, fish, slaughter-house refuse, etc., mixed in piles with lime, barn manure, woods-earth, swamp muck, peat and soil.

The object of composting these materials is to hasten their decay and render available the plant food in them.

There are certain disadvantages in composting, namely:

Expense of handling and carting on account of bulk.

Low composition.

Loss of organic matter by fermentation.

Compost heaps serve as homes for weed seeds, insects and plant diseases.

Nevertheless, all waste organic matter on the farm should be saved and made use of as manure. These materials when not too coarse may be spread on the surface of the soil and plowed under; they should never be burned unless too coarse and woody or foul with weed seeds, insects and disease.



CHAPTER XX

FARM MANURES—CONCLUDED

GREEN-CROP MANURES

Green-crop manures are crops grown and plowed under for the purpose of improving the fertility of the soil.

The main object of turning these crops under is to furnish the soil with humus. Any crop may be used for this purpose.

By growing any of the class of crops called Legumes we may add to the soil not only humus but also nitrogen. Cowpeas, beans, clover, vetch and plants having foliage, flowers, seed pods and seeds like them are called Legumes.

Most of the farm plants take their nitrogen from the soil. This nitrogen is taken in the form of nitric acid and nitrogen salts dissolved in soil water. The legumes, however, are able to use the free nitrogen which forms four-fifths of the atmosphere. This they do not of their own power but through the aid of very minute plants called bacteria or nitrogen-fixing germs. These germs are so small that they cannot be seen without the use of a powerful microscope. It would take ten thousand average sized bacteria placed side by side to measure one inch.

These little germs make their homes in the roots of the legumes, causing the root to enlarge at certain points and form tubercles or nodules (Figs. 34 and 35).

Carefully dig up a root of clover, cowpea, soy bean or other legume and wash the soil from it. You will find numbers of the little tubercles or nodules. On the clover they will be about the size of a pin head or a little larger. On the soy bean they will be nearly as large as the beans. These nodules are filled with colonies or families of bacteria which take the free nitrogen from the air which penetrates the soil and give it over to the plant in return for house rent and starch or other food they may have taken from the plant.

In an experiment at Cornell University Agricultural Experiment Station, in 1896, clover seeds were sown August 1st, and the plants were dug November 4th, three months and four days after the seeds were sown. The clovers were then weighed and tested and the following results were obtained:

+ NITROGEN IN AN ACRE OF CLOVERS. + - - Lbs. in tops. Lbs. in roots. Lbs., total. - - Crimson Clover 125.28 30.66 155.94 Mammoth Clover 67.57 78.39 145.96 Red Clover 63.11 40.25 103.36 - -

A large part of the nitrogen found in these plants was undoubtedly taken by the roots from the soil air.

Besides adding humus and nitrogen to the soil the legumes, being mostly deep-rooted plants, are able to take from the subsoil food which is out of reach of other plants. This food is distributed throughout the plant and when the plant is plowed under the food is deposited in the upper soil for the use of shallow-rooted plants.

BENEFITS

The benefits derived from green crop manuring then are as follows:

We add to the soil organic matter or humus which is so helpful in bringing about the conditions necessary for root growth.

By using the legumes for our green manure crops we may supply the soil with nitrogen taken from the air.

We return to the surface soil not only the plant food taken from it but also plant food brought from the subsoil by the roots of the green manure plants.

CHARACTER OF BEST PLANTS FOR GREEN CROP MANURING

The plants best adapted to green crop manuring are deep-rooted, heavy-foliaged plants. Of these the legumes are by far the best, as they collect the free nitrogen from the air which other plants cannot do. This enables the farmer to grow nitrogen which is very expensive to buy.

THE TIME FOR GROWING GREEN MANURE CROPS

Green manure crops may be grown at any time that the soil is not occupied by other crops, provided other conditions are suitable. Land which is used for spring and summer crops often lies bare and idle during fall and winter. A hardy green manure crop planted after the summer crop is harvested will make considerable growth during the fall and early spring, and this can be plowed under for the use of the following summer crops. If there is a long interval of time during spring or summer when the land is bare, that is a good time for a green manure crop.

Green manure crops are often planted between the rows of other crops such as corn or cotton at the last working of the crop for the benefit of the crop which is to follow.

It is advisable to arrange for a green manure crop at least once in three or four years.

LEGUMINOUS GREEN MANURE CROPS

Cowpea. (Field pea, stock pea, black pea, black-eyed pea, clay pea, etc.) (Fig. 79.)

The cowpea is perhaps the most important leguminous plant grown for soil improvement in the South. It will grow anywhere south of the Ohio River and can be grown with fair success in many localities farther north.

It is a tender annual, that is, it is killed by frost and makes its entire growth from seed to seed in a single season. It should therefore be planted only during the spring and summer. This crop not only has power like the other legumes to take nitrogen from the air, but it is also a strong feeder, that is, it can feed upon mineral plant food in the soil that other plants are unable to make use of. For this reason it will grow on some of the poorest soils, and is a good plant with which to begin the improvement of very poor land. It is a deep-rooted plant. On the farm of the Hampton Normal and Agricultural Institute cowpea roots have been traced to the depth of sixty-one inches.

Cowpeas will grow on almost any land that is not too wet. From one and one-half to three bushels of seed are used per acre. These are sown broadcast and harrowed in or are planted in drills or furrows and cultivated a few times. Aside from its value as a green manure crop the cowpea is useful as food for man and the farm animals. The green pods are used as string beans or snaps. The ripened seeds are used as a food and the vines make good fodder for the farm animals.

"Experiments at the Louisiana Experiment Station show that one acre of cowpeas yielding 3,970.38 pounds of organic matter, turned under, gave to the soil 64.95 pounds of nitrogen, 20.39 pounds of phosphoric acid and 110.56 pounds of potash."—Farmer's Bulletin, 16 U.S. Dept. of Agriculture.

"It is now grown in all the States south of the Ohio River, and in 1899 there were planted nearly 800,000 acres to the crop. Basing our estimate on the amount of nitrogen stored in the soil by this crop, it is fair to say that fully fifteen million pounds of this valuable substance were collected and retained as a result of the planting of the cowpea alone. This at fifteen cents per pound (the market price of nitrogen) would be worth something more than $2,000,000 for nitrogen alone."—Year Book of the Department of Agriculture, 1902.

The Clovers.—These are the most extensively grown plants for green manure purposes in the United States. They are deep-rooted, and are able to use mineral food that is too tough for other plants. They furnish large crops of hay or green forage and a good aftermath and sod to turn under as green manure, or the entire crop may be plowed under.

Red Clover is the most widely planted (Fig. 80). It is a perennial plant and grows from the most northern States to the northern border of the Gulf States. It grows best on the loams and heavier soils well supplied with water, but not wet. It is sown broadcast at the rate of from ten to twenty pounds of seed per acre. In the North it is generally sown in the spring on fields of winter grain. In the South, September and October are recommended as the proper sowing times. It is the custom to let it grow two years, cutting it for hay and seed, and then to turn the aftermath and sod under.

Mammoth Red Clover, also called sapling clover and pea-vine clover, closely resembles the red clover, but is ranker in growth and matures two or three weeks later. It is better adapted to wet land than the red clover.

Crimson Clover, also called German clover and Italian clover, is a valuable green manure crop in the central and southern States east of the Mississippi. It is a hardy annual in that section and is generally sown from the last of July to the middle of October, either by itself or with cultivated crops at their last working. Fifteen and twenty pounds of seed are used to the acre. It makes a good growth during the fall and early winter and is in blossom and ready to cut or plow under in April or May. It grows at a season when the cowpea will not live. Crimson clover will grow on soils too light for other clovers.

The Soy Bean, also called soja bean and Japanese pea, is another leguminous crop used for green manuring (Fig. 81). It was introduced into this country from Japan and in some localities is quite extensively planted. It grows more upright than the cowpea and produces a large amount of stem and foliage which may be used for fodder or turned under for green manure The seeds are used for food for man and beast. The soy bean is planted and cared for in the same manner as the cowpea.

The Canadian Field Pea is sometimes grown in the north as a green manure crop.

White Sweet Clover, white melitot or Bokhara clover, grows as a weed from New England to the Gulf of Mexico. In the Gulf States it is regarded as a valuable forage and green manure plant. One or two pecks of seed per acre are sown in January or February.

Alfalfa, or lucern, though grown more for a forage crop than for green manuring, should be mentioned here, for wherever grown and for whatever purpose, its effects on the soil are beneficial (Fig. 82). This plant requires a well prepared soil that is free from weeds. Twenty to twenty-five pounds of seed are planted per acre. In the north the seeding is generally done in the spring after danger of frost is past, as frost kills the young plants. In the South fall seeding is the custom in order to give the young plants a long start ahead of the spring weeds. One seeding if well cared for lasts for many years. Alfalfa is pastured or cut for hay, four to eight tons being the yield. Many fields run out in five or six years and the sod is plowed under. This plant sends its roots thirteen, sixteen, and even thirty feet into the soil after water and food, and when these roots decay they furnish the lower soil with organic matter and their passages serve as drains and ventilators in the soil. Alfalfa is grown extensively in the semi-arid regions of the country.

NON-LEGUMINOUS GREEN MANURE PLANTS

Among the non-leguminous green manure plants are rye, wheat, oats, mustard, rape, buckwheat. Of these the rye and buckwheat are most generally used, the rye being a winter crop and the other a warm weather plant. They are both strong feeders and can use tough plant food. They do not add new nitrogen to the soil though they furnish humus and prepare food for the weaker feeders which may follow them.



CHAPTER XXI

COMMERCIAL FERTILIZERS

THE RAW MATERIALS

Next to the soil itself, the farmer's most important sources of plant food are the farm manures. But most farms do not produce these in sufficient quantities to keep up the plant food side of fertility. Therefore the farmer must resort to other sources of plant food to supplement the farm manures.

There is a large class of materials called Commercial Fertilizers, which, if judiciously used, will aid in maintaining the fertility of the farm with economy.

We learned in a previous chapter that the plant foods, nitrogen, phosphoric acid, potash and lime, are apt to be found wanting in sufficient available quantities to supply the needs of profitable crops. We learned also that lime is useful in improving the texture of the soil and in making other plant foods available. Now the commercial fertilizers are used to supply the soil with these four substances and they may be classified according to the substance furnished as follows:

Sources of nitrogen, " " phosphoric acid, " " potash, " " lime.

SOURCES OF NITROGEN

Nitrogen is the most expensive of plant foods to buy, therefore special attention should be given to producing it on the farm by means of barn manures and legumes plowed under.

The principal commercial sources of nitrogen are: Nitrate of soda, sulphate of ammonia, dried blood, tankage, dry ground fish, cotton-seed meal.

Nitrate of Soda or Chile saltpetre containing 15.5 per cent. of nitrogen, is found in large deposits in the rainless regions of western South America. In the crude state as it comes from the mine it contains common salt and earthy matter as impurities. To remove these impurities the crude nitrate is put into tanks of warm water. The nitrate dissolves and the salt and earthy matter settle to the bottom of the tank. The water with the nitrate in solution is then drawn off into other tanks from which the water is evaporated, leaving the nitrate, a coarse, dirty looking salt which is packed in three-hundred-pound bags and shipped.

Plants that take their nitrogen from the soil take it in the form of nitrate. Hence nitrate of soda, which is very soluble in water, is immediately available to plants and is one of the most directly useful nitrogen fertilizers. It is used for quick results and should be applied only to land that has a crop or is to be immediately planted, otherwise it is liable to be lost by leaching.

Sulphate of Ammonia contains 20 per cent. of nitrogen. It is a white salt, finer and cleaner looking than the nitrate. It is a by-product of the gas works and coke ovens. The nitrogen in it is quite readily available.

Dried Blood contains 8 to 12 per cent. of nitrogen. This is blood collected in slaughter-houses and dried by steam or hot air. It decays rapidly in the soil and is a quick acting nitrogen fertilizer.

Tankage contains 4 to 8 per cent. of nitrogen and 7 to 20 per cent. of phosphoric acid. Slaughter-house waste, such as meat and bone scrap, are boiled or steamed to extract the fat. The settlings are dried and ground and sold as tankage. It is much slower in its action than dried blood and supplies the crop with both nitrogen and phosphoric acid.

Dried Fish Scrap is a by-product of the fish oil factories and the fish canning factories. It contains 7 to 9 per cent. of nitrogen and 6 to 8 per cent. of phosphoric acid. It undergoes nitrification readily and is a quick acting organic source of nitrogen and phosphoric acid.

Cotton-seed Meal contains 7 per cent. of nitrogen, about 2.5 phosphoric acid, and 1.5 per cent. of potash. It is a product of the cotton oil factories and is obtained by grinding the cotton seed cake from which the oil has been pressed. It is a most valuable source of nitrogen for the South.

The nitrogen in the dried blood, tankage, fish scrap and cotton-seed meal, being organic nitrogen, must be changed by the process of nitrification to nitric acid or nitrate before it is available. They are therefore better materials to use for a more gradual and continuous feeding of crops than the nitrate of soda or sulphate of ammonia.

Scrap leather, wool waste, horn and hoof shavings are rich in nitrogen but they decay so slowly that they make poor fertilizers. They are used by fertilizer manufacturers in making cheap mixed fertilizers.

SOURCES OF PHOSPHORIC ACID

The principal commercial sources of phosphoric acid are:

Phosphate Rocks. Bones. Fish scrap. Phosphate slag.

The Phosphate Rocks are found in shallow mines in North and South Carolina, Georgia, Florida and Tennessee, and also as pebbles in the river beds. They are the fossil remains of animals. After being dug from the mines the rock is kiln dried and then ground to a very fine powder called "floats" which is used on the soil. The phosphoric acid in the floats is insoluble and becomes available only as the phosphate decays. This is too slow for most plants so it is treated with oil of vitriol or sulphuric acid to make it available. The phosphoric acid in the ground rock is combined with lime, forming a phosphate of lime which is insoluble. When treated with the oil of vitriol or sulphuric acid, the sulphuric acid takes lime from the phosphate and forms sulphate of lime or gypsum. The phosphoric acid is left combined with the smallest possible amount of lime and is soluble in water. It is then called soluble or water soluble phosphoric acid.

Now if this soluble form remains unused it begins to take on lime again and turns back toward its original insoluble form. After a time it gets to such a state that it is no longer soluble in water but is soluble in weak acids. It is then said to be reverted phosphoric acid. Reverted phosphoric acid is also called citrate soluble phosphoric acid, because in testing fertilizers the chemists use ammonium citrate to determine the amount of reverted phosphoric acid.

This form still continues to take on lime and by and by gets back to the original insoluble form called insoluble phosphoric acid.

The soluble phosphoric acid and reverted phosphoric acid are available to plant roots. The insoluble form is not.

The rock phosphates contain from 26 to 35 per cent. of insoluble phosphoric acid. The acid phosphates or dissolved rock phosphates contain from 12 to 16 per cent. of available phosphoric acid and from 1 to 4 per cent. of insoluble.

Bone Fertilizers. Bones have long been a valuable and favored source of phosphoric acid. In addition to phosphoric acid they contain some nitrogen which adds to their value. They are organic phosphates and are quite lasting in their effect on the soil as they decay slowly.

The terms "Raw Bone," "Steamed Bone," "Ground Bone," "Bone Meal," "Bone Dust," "Bone Black," "Dissolved Bone," indicate the processes through which the bone has passed in preparation, or the condition of the material as put on the market and used on the soil.

Ground bone, bone meal, bone dust, indicate the mechanical conditions of the bones.

The bones are sometimes ground "raw" just as they come from the slaughter-house or kitchen, or they are sometimes first "steamed" to extract the fat for soap, and the nitrogenous matter for glue.

Raw Bone. Analysis: Nitrogen, 2.5 to 4.5 per cent. Available phosphoric acid, 5 to 8 per cent. Insoluble phosphoric acid 15 to 17 per cent.

Steamed Bone contains 1.5 to 2.5 per cent. of nitrogen, 6 to 9 per cent. of available phosphoric acid and 16 to 20 per cent. of insoluble phosphoric acid.

Steamed bone pulverizes much finer than raw bone and decays more rapidly in the soil because the fat has been extracted from it.

Dissolved Bone. Ground bone is sometimes treated with sulphuric acid to render the phosphoric acid in it more available. It is then called dissolved bone and contains thirteen to fifteen per cent. of available phosphoric acid and two to three per cent. of nitrogen.

Dissolved Bone Black. Bone charcoal is used for refining sugar. It is then turned over to the fertilizer manufacturers who sell it as "Bone Black" or treat it with sulphuric acid and then put it on the market as dissolved bone black.

The bone black contains thirty to thirty-six per cent. of insoluble phosphoric acid.

The dissolved bone black contains 15 to 17 per cent. of available phosphoric acid and 1 to 2 per cent. insoluble.

"Thomas Slag," "Phosphate Slag," "Odorless Phosphate." Phosphorous is an impurity in certain iron ores. In the manufacture of Bessemer steel this is extracted by the use of lime which melts in the furnace, unites with the phosphorous and brings it away in the slag. This slag is ground to a fine powder and used as a fertilizer. It contains 11 to 23 per cent. of phosphoric acid, most of which is available.

Superphosphate. The term superphosphate is applied to the phosphates that have been treated with sulphuric acid to make the phosphoric acid available. Dissolved bone, dissolved bone black, and the dissolved phosphate rocks are superphosphates.

Fish Scrap, mentioned as a source of nitrogen, is also a valuable source of phosphoric acid, containing 6 to 8 per cent., which is quite readily available owing to the rapid decay of the scrap.

SOURCES OF POTASH

The chief sources of potash used for fertilizers are the potash salts from the potash mines at Stassfurt, Germany, where there is an immense deposit of rock salt and potash salts.

The principal products of these mines used in this country are the crude salts:

Kainite, containing 12 per cent. of potash.

Sylvinite, containing 16 to 20 per cent. of potash, and the higher grade salts manufactured from the crude salts:

Muriate of Potash, containing 50 per cent. potash.

High grade Sulphate of Potash, containing 50 per cent. potash.

Low grade Sulphate of Potash, containing 25 per cent. potash.

Wood Ashes, if well kept and not allowed to get wet and leach, contain 4 to 9 per cent. of potash.

Cotton Hull Ashes contain 20 to 30 per cent, of potash and 7 to 9 per cent. of phosphoric acid.

The potash in all these forms is soluble in water and equally available to plants. The crude salts, kainite and sylvinite, and the muriate contain chlorine and are not considered good for potatoes and tobacco as the chlorine lowers the quality of these products.

In tobacco regions tobacco refuse is a valuable source of potash, the stems are about five per cent. potash.

LIME

Lime is generally supplied to the soil in the form of quicklime made by burning lime stone or shells. Other forms are gypsum or land plaster, gas lime (a refuse from gas works) and marl. Most soils contain sufficient lime for the food requirements of most plants. Some soils, however, are deficient in lime and some crops, particularly the legumes, are benefitted by direct feeding with lime.

Lime is valuable for its effect on the soil properties which constitute fertility.

Physically lime acts on the texture of the soil making clay soils mealy and crumbly, and causing the lighter soils to adhere or stick together more closely.

Chemically, lime decomposes minerals containing potash and other plant foods, thus rendering them available for the use of plants. It also aids the decay of organic matter and sweetens sour soils.

Biologically lime aids the process of nitrification.

The action of lime is greatest in its caustic or unslacked form.

Too much or too frequent liming may injure the soil. It should be carefully tried in a small way, and its action noted, before using it extensively.

A common way of using lime is to place twenty to forty bushels on an acre in heaps of three to five bushels, covering them with soil until the lime slacks to a fine powder. The lime is then spread and harrowed in. Lime tends to hasten the decay of humus. It should not be applied oftener than once in four or five years.

Gypsum, a sulphate of lime, is similar to lime in its action on the soil. Its most important effect is the setting free of potash from its compounds.

Gas lime should be used with great care as it contains substances that are poisonous to plant roots. It is best to let it lie exposed to the weather several months before using.

Marl is simply soil containing an amount of lime varying from five to fifty per cent. It has value in the vicinity of marl beds but does not pay to haul very far.



CHAPTER XXII

COMMERCIAL FERTILIZERS—CONTINUED

MIXED FERTILIZERS

What they are.

There are a large number of business concerns in the country which buy the raw materials described in Chapter XXI, mix them in various proportions, and sell the product as mixed or manufactured fertilizers. If these mixtures contain the three important plant foods, nitrogen, phosphoric acid and potash, they are sometimes called "complete" manures or fertilizers. In some parts of the country all commercial fertilizers are called "guano."

Many brands.

These raw materials are mixed in many different proportions and many dealers have special brands for special crops. There are consequently large numbers of brands of fertilizers which vary in the amounts, proportions and availability of the plant foods they contain. For instance, in 1903, twenty-three fertilizer manufacturers offered for sale ninety-six different brands in the State of Rhode Island. In Missouri one hundred and ten brands, made by sixteen different manufacturers, were offered for sale. Eighty-three manufacturers placed six hundred and forty-four brands on the market in New York State during the same year. Of one hundred and twenty brands registered for sale in Vermont in the spring of 1904, there were seventeen mixtures for corn and thirty-four for potatoes.

The result of this is more or less confusion on the part of the farmer in purchasing fertilizers, and with many a farmer it is a lottery as to whether or not he is buying what his crop or his soil needs.

Some of the manufacturers are not above using poor, low grade, raw materials in making these mixtures.

This means that the farmer should make himself familiar with the subject of fertilizers if he desires to use them intelligently and economically.

Safeguard for the farmer.

As a safeguard to the buyer of fertilizers the State laws require that every brand put on the market shall be registered and that every bag or package sold shall have stated on it an analysis showing the amounts of nitrogen, or its equivalent in ammonia, the soluble phosphoric acid, the reverted phosphoric acid, the insoluble phosphoric acid, and the potash.

This registration is generally made at the State experiment station, and the director of the station is instructed to take samples of these brands and have them analyzed, and publish the results together with the analysis guaranteed by the maker.

These analyses are published in bulletin form and should be in the hands of every farmer who makes a practice of using commercial fertilizers.

The manufacturers of fertilizers comply with the law by printing on the bag or package the per cents of plant food in the fertilizers, and these statements in the great majority of cases agree favorably with the analyses of the experiment stations, but they do not in all cases state what materials were used to furnish the different kinds of plant food, and it is not always possible to find this out by analysis.

Low grade materials.

For instance in mixing a fertilizer one manufacturer may use dried blood to furnish nitrogen and another may use leather waste or horn shavings. The latter contains more nitrogen than the dried blood, but they are so tough and decay so slowly that they are of little benefit to a quick growing plant.

Inflating the guarantee.

Although the dealer states correctly the per cents of plant food in the fertilizer, he is quite frequently inclined to repeat this in a different form, and thus give the impression that the mixture contains more than it really does.

The dealers also give the nitrogen as ammonia because it makes a larger showing.

Phosphoric acid is often stated as "bone phosphate" because in this the amount appears to be greater.

For example, an analysis taken from a fertilizer catalogue reads as follows:

Ammonia 2 to 3 per cent. Available Phosphoric Acid 8 to 10 " Total Phosphoric Acid 11 to 14 " Total Bone Phosphate 23 to 25 " Actual Potash 10 to 12 " Sulphate of Potash 18 to 20 "

A better statement would be as follows:

Nitrogen 1.65 per cent. Available Phosphoric Acid 8 " Total Phosphoric Acid (furnished in Bone Phosphate) 11 " Potash (furnished in Sulphate of Potash) 10 "

Ammonia is reduced to terms of nitrogen by multiplying by .824. All bone phosphate is forty-six per cent. phosphoric acid. When bone phosphate is given instead of phosphoric acid it simply makes the mixture appear to have more in it, and when both phosphoric acid and bone phosphate are stated one is merely a repetition of the other. The same is true of the statements, potash and sulphate of potash, one is a repetition of the other only a different form.

VALUATION

The experiment stations not only publish comparative analyses of the registered fertilizers but they also compute the market values of the plant food contained in them and compare these valuations with the selling price of the fertilizers.

They also furnish a list of trade values of the plant foods in raw materials for the convenience of fertilizer buyers in testing the values of the brands offered them on the markets.

In the following list are given the "trade values agreed upon by the Experiment Stations of Massachusetts, Rhode Island, Connecticut, New Jersey and Vermont, after a careful study of prices ruling in the larger markets of the southern New England and Middle States."

Trade values of fertilizing ingredients in raw materials and chemicals for 1904:

Cents per lb. Nitrogen in Nitrates 16 Nitrogen in Ammonia Salts 171/2 Organic Nitrogen in dry and fine ground fish, blood, and meat, and in mixed fertilizers 171/2 Organic Nitrogen in fine ground bone and tankage 17 Organic Nitrogen in coarse bone and tankage 121/2 Phosphoric Acid soluble in water 41/2 Phosphoric Acid soluble in ammonium citrate 4 Phosphoric Acid in fine ground bone and tankage 4 Phosphoric Acid in coarse bone and tankage 3 Phosphoric Acid (insoluble in water and in ammonium citrate) in mixed fertilizer 2 Potash as high-grade sulphate and in mixtures free from muriate (chloride) 5 Potash as muriate 41/4

For example, in calculating the commercial value of the plant food in a fertilizer we will take the formula mentioned on page 205, namely:

Ammonia 2 to 3 per cent. Available Phosphoric Acid 8 to 10 " Total Phosphoric Acid 11 to 14 " Total Bone Phosphate 23 to 25 " Actual Potash 10 to 12 " Sulphate of Potash 18 to 20 "

This fertilizer is evidently a mixture of bone meal and sulphate of potash and the plant food contained in it is as follows:

Nitrogen 1.65 per cent. Available Phosphoric Acid 8 " Insoluble Phosphoric Acid 3 " Potash 10 "

One hundred pounds of the mixture would contain:

Pounds. Value per 100 lbs. Nitrogen 1.64 value at 171/2c .29 Available Phosphoric Acid 8 " " 4c .32 Insoluble Phosphoric Acid 3 " " 2c .06 Potash 10 " " 5c .50 ——- Total $1.17

In one ton the whole value would be twenty times this or $23.40. Add to this $8, which is about the average charge for mixing, bagging, shipping, selling and profit, and we find that $32 is probably the lowest figure at which this fertilizer could be purchased on the markets, and very likely the price would be higher as we have taken the lowest guaranteed per cent. of plant food for our basis of calculation.

Fertilizers are generally mixed and sold to the farmer on the ton basis.

LOW GRADE MIXTURES

Most dealers, to meet a certain demand, furnish mixtures ranging from $15 to $25 per ton. These mixtures are necessarily low grade and are more expensive than the higher priced high grade mixtures.

For example:

A certain potato fertilizer on the market, which we will call mixture A, has the following guaranteed analysis:

Ammonia 7 to 8 per cent. Available Phosphoric Acid 6 to 7 " Actual Potash 5 to 6 "

A ton of this would contain:

Pounds. Nitrogen 115.4 value at 171/2c $20.19 Available Phosphoric Acid 120 " " 4c 4.80 Potash 100 " " 5c 5.00 ——- ——— Totals 335.4 $29.99

Add to this the average charge for mixing, bagging, selling, profit, etc., $8, and the cost will be $37.99.

The selling price of this fertilizer would probably be not less than $40. Now suppose the farmer thinks this a high priced and expensive fertilizer and looks about for something cheaper. He finds a low grade potato fertilizer, which we will call mixture B, that has the following guarantee:

Ammonia 31/2 to 4 per cent. Available Phosphoric Acid 3 to 31/2 " Actual Potash 21/2 to 3 "

Just one-half the guarantee of the high grade mixture A. A ton of this contains:

Pounds. Nitrogen 57.7 value at 171/2c $10.10 Available Phosphoric Acid 60 " " 4c 2.40 Potash 50 " " 5c 2.50 ——- ——— Totals 167.7 $15.00 Add average charge for mixing, etc. 8.00 ——— $23.00

The selling price of this would very likely be not less than $25.

This seems at first sight to be cheaper and more reasonable. But let us see.

In a ton of mixture A he gets 335.4 pounds of plant food for $40, or at an average cost of twelve cents per pound, while in a ton of mixture B he gets 167.7 pounds of plant food for $25, or at an average cost of fifteen cents per pound.

To put it another way, in a ton of the high grade mixture A, he gets 335.4 pounds of plant food for $40. To get the same amount of plant food, 335.4 pounds, in the low grade mixture, B, it will be necessary to buy two tons at a cost of $50.

A low grade fertilizer is always expensive even if the plant food is furnished by high grade materials.

BUY ON THE PLANT FOOD BASIS

The farmer generally buys his fertilizer on the ton basis. A better method is to buy just as the fertilizer manufacturers buy the raw materials they use for mixing, namely, on the basis of actual plant food in the fertilizer. The dealers have what they call the "unit basis," a "unit" meaning one per cent. of a ton or twenty pounds of plant food. A ton of nitrate of soda, for instance, contains 310 pounds or 151/2 units of nitrogen, which at $3.20 cents per unit would cost $49. Buy your mixture of a reliable firm, find out the actual amounts of the plant foods in the mixture and pay a fair market price for them.



CHAPTER XXIII

COMMERCIAL FERTILIZERS—CONCLUDED

THE HOME MIXING OF FERTILIZERS

When a considerable amount of fertilizer is used a better plan than buying mixed fertilizer is to buy the raw materials and mix them yourself. For example, a farmer is about to plant five acres of cabbages for the market. He finds that a certain successful cabbage grower recommends the use of fifty pounds nitrogen, fifty pounds phosphoric acid and seventy pounds potash per acre. For the five acres this will mean 250 pounds nitrogen, 250 pounds phosphoric acid and 350 pounds potash. To furnish the nitrogen he can buy 1,613 pounds of nitrate of soda or 2,500 pounds dried blood or 1,250 pounds sulphate of ammonia, or a part of each. To furnish the phosphoric acid he can buy 1,786 pounds acid phosphate. Seven hundred pounds of either sulphate or muriate of potash will furnish the potash. These materials can be easily mixed by spreading in alternate layers on a smooth floor and then shovelling over the entire mass several times. The mixture can be further improved by passing it through a sand or coal screen or sieve.

By following this method of buying the raw materials and mixing them on the farm, the farmer can reduce his fertilizer bill by quite a considerable amount and at the same time can obtain just the kinds and proper amounts of plant foods needed by his crops.

KIND AND AMOUNT TO BUY

The farmer should make the best use of farm manures and through tillage to render plant food available for his crops before turning to commercial fertilizer for additional plant food.

If he grows leguminous crops for green manuring, for feeding stock or for cover crops, he can in many cases secure, chiefly through them, sufficient high priced nitrogen for the needs of his crops, and it is necessary only occasionally to purchase moderate amounts of phosphoric acid, potash and lime.

For special farming and special crops it may be necessary to use the commercial fertilizer more freely.

It is impossible to say here just what amounts or what kinds of fertilizer should be purchased, because no two farms are exactly alike as to soil, methods of cropping or methods of tillage.

There are certain factors, however, which will serve as a general guide and which should be considered in determining the kind and amount of fertilizer to buy.

These factors are:

The crop. The soil. The system of farming.

THE CROP

Crop roots differ in their powers of feeding, or their powers of securing plant foods. Some roots can use very tough plant foods, while others require it in the most available form. Some roots secure nitrogen from the air. The cowpea roots, for example, can take nitrogen from the air and they can use such tough phosphoric acid and potash that it seldom pays to feed them directly with fertilizers.

A bale per acre crop of cotton requires for the building of roots, stems, leaves, bolls, lint and seed:

103 pounds of Nitrogen. 41 " " Phosphoric Acid. 65 " " Potash.

and yet experiment and experience have proved that the best fertilizer for such a crop contains the following amounts of plant food:

Nitrogen 20 pounds Phosphoric Acid 70 " Potash 20 "

This means that cotton roots are fairly strong feeders of nitrogen and potash, but are weak on the phosphoric acid side.

The small grains, wheat, oats, barley and rye, can use tough phosphoric acid and potash, but are weak on nitrogen, and as they make the greater part of their growth in the cool spring before nitrification is rapid, they are benefitted by the application of nitrogen, particularly in the form of nitrate, which is quickly available.

Clover, peas, beans, etc., have the power of drawing nitrogen from the air, but draw from the soil lime, phosphoric acid and potash. Hence the phosphates, potash manures and lime are desirable for these crops.

Root and tuber crops are unable to use the insoluble mineral elements in the soil, hence they require application of all the important plant foods in readily available form. Nitrogen is especially beneficial to beets. Turnips are benefitted by liberal applications of soluble phosphoric acid. White and sweet potatoes require an abundance of potash.

If we are growing tender, succulent market garden crops, we need nitrogenous manures, which increase the growth of stem and foliage.

Fruit trees are slow growing plants and do not need quick acting fertilizers.

The small fruits, being more rapid in growth, require more of the soluble materials.

A dark, healthy green foliage indicates a good supply of nitrogen, while a pale yellowish green may indicate a need of nitrogen.

A well developed head of grain, seed pod or fruit indicates liberal supplies of phosphoric acid and potash.

THE SOIL

Soils that are poor in humus are generally in need of nitrogen.

Heavy soils are generally supplied with potash but lack phosphoric acid.

Sandy soils are apt to be poor in potash and nitrogen.

SYSTEM OF FARMING

A system of general or diversified farming embracing crop products and stock raising, requires much less artificial manuring than does a system which raises special crops or quick growing crops in rapid succession, as in the case of truck farming or market gardening.

TESTING THE SOIL

Every farmer should be more or less of an investigator and experimenter.

The factors mentioned previously as indicating the presence or absence of sufficient quantities of certain plant foods serve as a general guide, but are not absolute. The best method of determining what plant foods are lacking in the soil is to carry on some simple experiments.

The following plan for soil testing with plant foods is suggestive: To test the soil for a possible need of the single plant foods, a series of five plots may be laid off. These plots should be long and narrow and may be one-twentieth, one-sixteenth, one-tenth, one eighth acre or larger. A plot one rod wide and eight rods long will contain one-twentieth acre. The width of the plot may be adjusted to accommodate a certain number of rows of crop and the length made proper to include an even fraction of an acre. A strip three or four feet in width should be left between each two plots. These strips are to be left unfertilized and are for the purpose of preventing one plot being affected by the plant food of another.

The plots are all plowed, planted and cared for alike, the only difference in treatment being in the application of plant food. If the plots are one-twentieth acre in size, plant foods may be applied as follows.

PLOT 1. Nitrate of Soda 8 lbs.

PLOT 2. Acid Phosphate 16 lbs.

PLOT 3. Nothing.

PLOT 4. Muriate of Potash 8 lbs.

PLOT 5. Lime 1 bushel.

Plot 3 is a check plot for comparison.

The measuring of the plots, weighing and application of the fertilizers, planting and care of the crops, weighing and measuring at harvest, should be carefully and accurately done.

A number of additional plots may be added if desired to test the effect of plant foods in combination. For instance:

PLOT 6. Nitrate of Soda 8 lbs. Acid Phosphate 16 "

PLOT 7. Nitrate of Soda 8 lbs. Muriate of Potash 8 "