Types of Plows.—The kind and condition of the soil, and the character of the crop, determine the type of plow to be used. A plow with a short and quite straight moldboard does not bury manure and turf in the bottom of the furrow so completely as is the case with a long, curved moldboard. The organic matter should be distributed throughout all the soil. On the other hand, it is essential to some plants that they have a fine seed-bed, and one whose surface is free from tufts of grass. The long moldboard is preferred in breaking a sod for corn. Its use in plowing for all crops is more general than it should be, the gain in pulverization of the furrow-slice, due to the curve, and the neatness in appearance of the plowed land, inducing its use.
The disk plow has been used chiefly in soils not requiring deep plowing. It pulverizes better than a moldboard plow, and buries trash more easily.
Deep tillage.
The device for using two disks to turn a single furrow-slice rests upon a sound principle. This plow may be set to run deeper than moldboard plows go, and it mixes well all the soil that it turns. The disks are so hung that the mixing of all the soil to a depth of twelve or fifteen inches is admirable. The deep-tilling plow does not bury the organic matter in the bottom of the furrow, and thereby permits the deepening of the soil without bringing an undue amount of subsoil to the surface.
Subsoiling.—The theory of subsoiling always has been captivating. Most soils are too shallow, inviting injury from drouth. Enthusiasm regarding subsoiling comes to large numbers of farmers at some time in their experience, and a great number of subsoil plows have been bought. The check to enthusiasm is the fact that few men ever have seen such a plow worn out. Some reasons are as follow:
(a) The subsoil at time of spring-plowing rarely is dry enough for good results, and there is danger of puddling; (b) the subsoil often is too dry and hard in late summer, when rains permit easy breaking of the top soil for fall grain; (c) the work doubles the labor and time of plowing, and (d) the subsoil soon settles together because it contains little organic matter. Subsoiling is generally approved and little practiced. Land at plow-depth becomes packed by the tramping of horses upon it and the pressure of the plow, when the plowing is done at the same depth year after year, and in some soils subsoiling has been found distinctly valuable.
Time of Plowing.—In great measure the time of plowing is determined by the effect upon soil moisture, and is discussed in the next chapter.
Method of Plowing.—The depth of plowing should be fixed largely by the amount of organic matter in the soil. It is essential that a good percentage of this material should be mixed throughout the soil, and when it is in scant supply, the depth of plowing usually should not be great. Fertile soils should be plowed deep for their own good, and thin soils should be deepened gradually, as sods and manures afford a supply of humus-making material. Even when manure is used liberally in a single application on a poor soil, a large amount of inert subsoil should not be thrown upon the surface. The manure goes out of reach of the greatest need, which is in the surface soil where plant-life starts. A gradual process of deepening the soil is to be preferred, but such deepening should not be neglected. The subsoil is a store of inert fertility that should not remain dormant.
It may not do to say that the success of the best farmers is due to thoroughness in plowing, but it is true that the more successful ones are insistent that the plowing be absolutely thorough. Every inch of the soil should be stirred to a certain depth, and that requires a plow so set that it does not turn a furrow-slice much wider than the point can cut. Evenness in depth and width of furrow is seen in good plowing.