Chapter IX

Crops and Crop Rotation

71. Main Crop Desirable.

In most farming regions some leading crop usually becomes the main market or feed crop. This is desirable in most instances because it gives opportunity for specialization in one crop or commodity. The main crop is usually chosen because of especial adaptation to climate and soil, or because of market facilities for that crop, or because of labor conditions favorable to its growth.

In the Dakotas, Minnesota and Canada, wheat has been the leading crop on most farms. It will continue to be the leading crop so long as satisfactory yields are secured, and shipping facilities are good. The wheat crop is especially adapted to new regions where the product must be shipped long distances to market. It stands transportation well. Less capital is required to equip for wheat raising than for stock raising and is favored for that reason also. And many who settle on new lands do not care to take up the more complex systems of farming. In Illinois, Indiana, and other Central states, Indian corn is the leading crop, and the one which determines largely the system of farming. Likewise, the Southern and Southeastern states are especially adapted to cotton and fruit growing. In some sections, cotton leads, in others fruit growing is the main line of production. Kansas, Utah, and some of the other Western states are especially adapted to alfalfa growing; California to fruit growing, oranges, grapes and lemons being specialties. The New England states are more concerned with the production of hay and dairy products.

72. Dangers of Continuous Cropping.

Where single line farming is followed extensively, there are grave dangers and trouble is likely to be experienced either from (1) weeds, (2)

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insect pests, or (3) plant diseases. In the spring-grain growing territory, wild oats and wild mustard become serious pests. Many of the fields in the spring-grain growing states are so badly infested with these weeds that yields are materially reduced, because large areas are farmed and it is sometimes impossible to plow all of the land. As a consequence, the land is disced in the spring and grain sown in the stubble of the crop of the previous year. On land so farmed, Russian thistles, Canada thistles, wild rose bushes, and the weeds above mentioned have secured a strong foothold. The chinch-bug

[Illustraion: Fig. 37.--On the left is corn growing on land that has grown corn continuously for 19 years. On the right is corn in a five-year rotation. Both fields were planted on the same day to the same kind of corn. The yield on the field to the left is 27.5 bushels an acre. The field on the right gives 61.3 bushels an acre. These are the average yields for ten years.]

is a common enemy to the spring-wheat growers. The clover midge is likely to infest clover fields unless frequent changes are made. The corn root louse and corn root worm infest the land that is planted continuously to corn. Flax growing has been discontinued in some regions because the land has become infested with the disease known as wilt. Recently, investigators have found that fungus diseases attack the roots of the small grain plants when continuously grown, interfering with the full development of the plants and reducing the yield. Smut and rust of wheat are likely to follow continuous wheat

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growing. Corn smut infests the crop grown on land that has produced corn continuously. There are many adverse conditions and diseases which are met by the one who tries to grow a single crop for any number of years on the same piece of land.

73. Difficulties Avoided by Crop Rotation.

Most of these difficulties may be avoided by crop rotation. It does not necessarily follow that because crops are rotated, a main or leading crop cannot be grown. The combination of fields and the arrangement of crops may be made in such a way that more of the main product is secured than where single line farming is followed. The yields on the rotation plots at University Farm, Minnesota,

[Illustration: Fig. 38.--An old alfalfa field after plowing. Note the roots in the soil. In decaying, these form humus.]

indicate that as much wheat can be produced in three years by rotation the crops, as can be produced in four years of continuous cropping. There is also much less trouble from weeds and insect pests, and moisture conditions are more easily controlled.

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[Illustration: Fig. 39.--On the left at the top is corn growing on an alfalfa field that has been plowed up. Beneath it is a shovelful of dirt from the field. Note the presence of roots and other vegetable matter. At the right is corn growing on land raising corn continuously. Beneath it is a shovelful of dirt from it. Note the absence of vegetable matter of any kind.]

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     Crop rotation means only a proper classification of crops and a systematic and fairly regular change (rotation) in the order of growing. In arranging the crops in rotation, however, especial attention should be given to providing crops which will restore the organic matter in the soil. The legume crops are desirable for this purpose as they supply nitrogenous material in larger quantities than the other crops.

74. Farm Crops Classified.

Farm crops may be thrown into three rough groups, for the purpose of arranging crop rotations; (1) grain crops; (2) grass crops; (3) cultivated crops.

     The grain crops include wheat, oats, barley, flax, rye, and such other cereals as may be grown for the mature grain. The roots of all of these crops are shallow and feed near the surface. A part of the plants, the stubble, is returned to the soil and the crop may be said to be neutral as to the destruction of vegetable matter in the soil.

     The grass crops include timothy, red top, blue grass, bromus, orchard grass, rye grass, and others of the true grasses. Included with them are the clovers, alfalfa, cow peas, soy beans and such other leguminous crops as are ordinarily grown for forage. These crops produce a large amount of leaves, many of which are broken off and returned to the soil. The roots of the clovers and alfalfa penetrate deeply and aid materially in renovating and aerating the soil. The crowns and roots of all of these plants are large, and when plowed under or allowed to decay in the soil, add considerable vegetable matter. These crops are useful also in keeping down weeds and encouraging the production of live stock, thuse providing manures for the land. The grass crops may be said to increase the vegetable matter in the soil.

     The cultivated crops such as corn, cotton, potatoes, and root crops of all kinds, form the third group. While usually grown for the purpose of cleaning the fields of weeds, and looked upon as soil-building crops, they are as a matter of fact, more exhaustive of soil fertility than grain or grass crops. The frequent

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cultivation breaks down the vegetable matter rapidly. The destruction of vegetable matter renders the soil hard and compact. Air does not enter readily and moisture conditions are not so good as in the soil that contains a large amount of decaying plant matter. The roots of the cultivated crops supply little or no vegetable matter and where grown continuously, the soil usually gets in bad physical condition. The cultivated crops are very destructive of vegetable matter.

     Harmful results will follow continued production of any of these crops. A change of crop within the group should not be considered as crop rotation. A succession of wheat, oats, barley, and flax, going back to wheat and growing the crops in the same order, would be a change of crops but not a true rotation. The growth of timothy and clover followed by timothy raising for a number of years, would not be rotation, though it is a kind of farming frequently practiced, especially in the Eastern states. Any scheme of cropping which provides for the alternation of the crops included in the three groups, would be a true crop rotation. Grain, whether wheat, oats, barley, or some other cereal, followed by grass, such as timothy and clover, for one or two years and followed by a cultivated crop, such as corn or potatoes, and this in turn followed by another grain crop, would result in the change of crops and gives a suggestion of ideal crop rotation.

76. Examples of Good Rotations.

Combinations of crops are so numberous that it would be impossible to give all. A few standard rotations are included as suggestive of what may be done in properly arranging crops for rotation purposes.

     In the spring-grain-growing regions, a five-year rotation of (1) wheat, seeded to timothy and clover; (2) meadow; (3) pasture, fall plowed; (4) grain (flax, oats, or wheat); (5) manured eight tons per acre, corn; is a popular and profitable rotation. A three-course rotation for the same section, where dairy and live stock raising is followed, would be, (1) grain, seeded to clover; (2) clover; (3) manured six tons per acre,

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corn. Where grain raising is followed extensively, a seven-course rotation is sometimes practiced. The following is a favorite one: (1) Manured ten tons an acre, corn; (2) wheat, seeded to timothy and clover; (3 and 4) grass; (5, 6, and 7) grain crops, with clover or rape among the grain, to be plowed under each fall as green manure.

[Illustration: Fig. 40.--One field for each year in rotation. Fields arranged for a three-year rotation.]

     In the Southern states where cotton raising is practiced extensively, rotation becomes somewhat difficult. The cotton is usually rotated with corn, but as corn is a cultivated crop, this rotation fails in maintaining soil fertility. A rotation that is highly recommended for this region is, (1) cotton; (2) corn, with cow peas between the rows; (3) oats, followed by cow peas. A rotation recommended by the Kansas Experiment Station for that region is (1) corn; (2) grain, seeded to clover and grass, (3 and 4) clover and hay or pasture. Alfalfa is one of the

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most valuable forage crops that can be grown. It is not adapted to short rotations, however, as it should remain for five or six years when once established. It can be used in rotation where the farm is so laid out that the rotation can be shifted once in each five or six years. A four-year rotation on a five-field farm or a five-year rotation on a six-field farm works successfully. The extra field stays in alfalfa until the end of the rotation cycle. In the corn belt it is customary to grow corn for two or three years, followed by oats one year, and in some cases clover is seeded with the oats and plowed under the next spring for corn. A four-year rotation of (1) corn, with cow peas, soy beans, or clover as a catch crop (clover sown at last cultivation); (2) oats, with wheat seeded in the fall; (3) wheat, with clover seeded in the spring; (4) clover (first crop used for hay, and second for seed or pasture) is recommended. For additional rotations suited to the needs of the other portions of the United States, see Bailey's Cyclopedia of American Agriculture, Vol. II, pages 99 to 109.

76. Rotation of Crops Not Difficult.

When the farm has been well planned and the fields regularly laid out, the rotation of crops is not difficult. In fact, the management of a farm under crop rotation becomes more or less automatic, and offers fewer perplexing problems than does the management of a farm which has irregular fields and no systematic method of cropping. Where two rotation cycles are followed, the cropping becomes more flexible than where only one is used. In this way, a change of crops can be made within rotations frequently, which will allow one to meet market fluctuations, seasonal disturbances, or changed labor conditions.

     In arranging rotations, it is only necessary that three groups of crops be included, and that the effect of each group upon the soil and upon the crops which are to alternate with it, be considered. It is not uncommon to divide the grain fields, sowing wheat on one portion, oats on another, and flax on a third. The effect of all these crops on the land is practically the same and all

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should be considered as grain crops. Frequently, only a small amount of one of the cultivated crops will be desired. It is possible to divide a field between corn, potatoes, and mangles, or between corn, cotton, and potatoes, getting the same effect on the land with each of the cultivated crops and giving opportunity for cleaning up the land. Likewise, divisions can be made of the grasses sown. So long as the main groups are observed and provision made for alternating the groups of crops, rather than the crops themselves, the rotation will have the desired effect.

[Illustration: Fig. 41.--Fields arranged for a five-year rotation.]

     It is important in planning a rotation system, that provision be made to have all fields drained and put in good working condition. It is possible to pasture a piece of land that contains a slough or a ditch without very much loss of time or labor. Such a field in hay, grain, or cultivated crops, is more difficult to work and results in considerable loss of itme. In fact, a slough in the center of the field may reduce the profit per acre to a considerable extent. In many instances it will require less time to work the land occupied by the slough, than it would take to run around it in avoiding the wet places. The fields should be uniform in size and regular in their boundaries to reduce the expense of working. There should be a field for each year in the rotation. With these three points provided for, rotation becomes easy and satisfactory. A farm on which the crops are rotated is likely to be much freer from weeds than one on which "hit and miss" farming is followed.

Exercises for Pupils

1. Have the pupils lay out plans for farms in several different ways, arranging rotations suited to the climate, soil, and markets of the locality.

2. Arrange 3, 4, 5 and 7 year rotations and study the yields and amounts, likely to be secured under each rotation. Tabulate in a crop ledger plan as shown in Chapter VIII.

Problems

     1. A field of 60 acres is in permanent pasture. Plan a three-year rotation which will grow 15 acres of potatoes, 7 1/2 acres of oats, 15 acres of clover, and 7 1/2 acres of barley.

     2. Clover in a rotation of wheat, clover, corn, and oats, increases the yield of wheat 3 bu., oats 6 bu., and corn 5 bushels. What is the increased return an acre from each grain crop if oats are worth 30 cents, corn 45 cents and wheat 90 cents? What is the total gain an acre from the grain crops in one rotation?

     3. An average wheat yield of 15 bushels an acre could be increased 4 bushels per acre by growing a crop of clover after two years of wheat. What would be the gain or loss on a three-year rotation of wheat, wheat and clover in comparison with three years of wheat, if it costs, including land rental, $7.18 to produce an acre of clover and $9.86 for an acre of wheat? The clover yields 2 1/2 tons an acre and sells for $8.00 a ton, and the wheat sells for 90 cents a bushel.

References

     Farm Management.--U.S. Department of Agriculture, Bureau of Plant Industry, Bulletin No. 236.
     Field crops.--Wilson & Warburton, pages 503-521.
     Minnesota Experiment Station Bulletin No. 109.
     Cyclopedia of American Agriculture.--L. H. Bailey, Vol. II, pages 92-109.

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