A Living from the Land

by William Budington Duryee

Another factor that militates against worth-while benefits of chemical soil analysis is the great variation in soil types frequently occurring in the same field. To attempt to draw a representative sample by mixing soil from several areas might result in a specimen that would not be really typical of any area. For the purpose of ordinary physical examination and testing for acidity, representative soil samples should be taken from several parts of the same soil type, mixed together and a composite sample for testing drawn from the mixture, weighing not less than a pound in each case. If the soil is quite apparently variable it may be necessary to draw two or more composite samples from the same area. Very helpful service in intelligent soil treatment may be secured from the county agricultural agent and the state college of agriculture in the county or state of residence.

Legumes as Soil Improvers.—A means of soil improvement that is well understood by progressive farmers is the use of legumes to improve the soil. The legumes include a large family of plants of which the bean, the pea and the clovers are outstanding examples. Such plants have on their roots nodules which house nitrogen-gathering bacteria. These bacteria absorb nitrogen from the air in the soil and, in the ordinary process of growth, death and decay, make this nitrogen available to the host plants, leaving a residue in the soil for the roots of plants that are to follow. Thus this group of plants, known as legumes, have been used for generations as a method of increasing the nitrogen content of soils. Nitrogen, incidentally, is the most costly element to buy in commercial fertilizers. The soil-improving benefits of legumes may be secured by growing them either for harvest as a source of animal food or for plowing under as a means of utilizing them entirely for the development of soil fertility.

In reading of the studies of soil fertility that were made by George Washington at Mount Vernon, we learn of the improvement that he made in the relatively poor soils of that area by growing plants of the legume family. The actual reason why such improvement was brought about was not known in Washington’s time, but the results were apparent. Today, the value of legumes as soil builders is well recognized and we understand much more definitely than Washington did the reasons for their being so helpful in increasing crop production.

Many soil areas do not contain the particular type of bacteria necessary to the fixation of atmospheric nitrogen by legumes. This is frequently the cause of failure in growing alfalfa, soybeans, cowpeas and less well known members of the legume family. Each legume has its own type of nodule-forming bacteria. In order to assure the presence of the proper bacterial family, means often must be employed to add them to the soil where the specific crop is to be grown. This may be accomplished by adding soil from an area where the legume does well to the new area, or the seed may be inoculated with commercial cultures before seeding. Either method is effective. If soil is used it should be drilled in or spread on a cloudy day to prevent the destructive action of the sun’s rays on the exposed minute forms of plant life we call bacteria.

If it is not known that the legume to be planted has been grown successfully in a given field within the previous several years, the precaution of adding the proper bacteria should be taken. In some sections, such legumes as red, alsike, crimson and white clovers have been grown for many years and the bacteria for these plants are well distributed. There, inoculation is not necessary for these crops, but it probably should be practiced if other legumes such as alfalfa, cowpeas or soybeans are to be grown on land for the first time.

The Value of Humus.—In addition to the chemical elements of plant food, all productive soils contain decaying vegetable matter, generally classified under the term “humus.” Humus serves as a source of acid-generating material which further breaks down soil particles and, most important of all, serves as a food for millions of microscopic plants which develop and die quite beyond the scope of human vision. These constitute a type of bacteria which are distinctly beneficial and essential to human life since they make possible the growth of larger plants that serve as human food.

Green plants, straw or leaves, when plowed under or spaded in the soil, are attacked by bacterial agencies which gradually turn these products into humus. The same process occurs when a “compost” is set up. This is made of leaves, manure, soil, straw and other materials thrown into a heap and allowed to decay. Such compost is excellent for placing around plants when setting them out, since it holds moisture, supplies fertility and creates optimum conditions for young root growth. Under practical field conditions, humus may be added to soils by spreading animal manures, followed by plowing them down, or by the growing of heavy green crops such as wheat, rye, cowpeas or vetch and turning the entire mass under with the plow when they are at their height.

Lime and Its Application.—Reference has been made to the fact that calcium is an essential plant food and is frequently deficient in soils. As a matter of fact, the great majority of soils are deficient in calcium and their productiveness is inhibited thereby. Lime supplies calcium and also magnesium as food for plants. Its application accomplishes many other desirable things such as correcting soil acidity. The growth of beneficial bacteria is greatly stimulated in a soil that has had its acidity neutralized by the application of lime. This product, therefore, creates a more congenial condition for the growth of bacteria, which, in turn, make for better crop production. Lime is also beneficial through furnishing the element calcium with which other plant foods combine chemically and thereby become soluble in the soil water. Unless plant foods are in a state of solution, they cannot be absorbed by plant roots. Lime is a potent force in creating chemical reactions in the soil, resulting in the stimulation of growth through increased absorption of essential elements in solution.

Lime also benefits soils of a clayey nature through its ability to cement together the fine clay particles and in that way create air spaces so greatly needed in tight clay soils. Lime is beneficial, too, in the case of soils which have a large proportion of sand or large particles, and serves as an agent in creating a better condition of tilth and of moisture retention.

It makes little difference in what form lime is applied. It may be purchased and applied in the form of ground limestone, a rock rich in calcium which has been mechanically ground to a very great degree of fineness. It can also be applied in the form of hydrated lime. This is obtained by heating ground limestone and slaking it by adding water. A common example of this is the slaking of lime for whitewashing purposes. Another good source of lime is finely ground shells of oysters or other forms of sea life which collect the calcium from sea water and deposit it in their shells.