FIG. 8–3. Parts of a wooden plow held together by animal-skin thongs. (Photo by Author.)
History of the Plow. Recorded history in the form of hieroglyphs and cuneiform characters shows that the ancients had a type of plow thousands of years B.C. It is recorded that about 900 B.C. Elisha was found “plowing with twelve yoke of oxen before him.”1 Figure 8–2 shows a farmer in eastern Turkey plowing with five yoke of oxen in 1950. The wooden plow with a metal share has been used for many centuries and millions of wooden plows are still in use today. The parts of the wooden plow shown in Fig. 8–3 were held together entirely by animal-skin thongs—there were no nails, bolts, or haywire available to this man, so he used what he could find.
The Roman plow, which was improved by the Dutch, was imported into England about 1730. The Essex plow of about 1756 had an iron moldboard. The Norfolk wheel plow of 1721 had a cast-iron share and an iron rounded moldboard. A curved moldboard made its appearance in 1760 on the Suffolk swing plow. The Rotherham plow was improved by James Small, who wrote a book on plow design in 1784. The close of the eighteenth century saw the change in England from the wooden plow to the iron plow.
In America, Thomas Jefferson and Daniel Webster were among the first to advance improvements of the plow. Charles Newbold of Burlington, New Jersey, secured the first patent on a cast-iron plow in 1797. Farmers rejected this iron plow because they thought it poisoned the soil. Jethro Wood developed a moldboard in 1814 of such curvature as to turn the soil in even furrows. The first steel plow was made from three sections of an old handsaw by John Lane about 1833. He also secured in 1868 a patent for soft-center steel, which is used at the present time in making moldboards for plows. In 1837, John Deere at Grand Detour, Illinois, made a steel plow (share and moldboard in one piece) from an old sawmill saw. Ten years later he established a factory at Moline, Illinois.
James Oliver was granted a patent in 1868 for hardening cast iron which was known as chilled iron.
In 1856, M. Furley patented a single-bottom sulky or wheel plow which permitted the operator to ride. In 1864, F. S. Davenport patented a riding two-bottom horse-drawn gang plow. Three- and four-bottom gang plows often required ten to twelve horses to pull them.
The large ten- to fifteen-bottom plows were pulled by steam tractors in the 1890’s and by the large, slow, cumbersome gasoline-engine tractors from about 1900 to 1910. The early two- to five-bottom trailing-tractor plows were equipped with hand-lever lifts. In the early twenties, mechanical power lifts were developed. They were used until the hydraulic lift was introduced in the forties. The integral-tractor-mounted unit assembly and unit-lifted plow were developed in the early forties by Ferguson. This type of plow is now becoming popular on small and average-sized farms.
The disk plow was probably developed about 1890. Models were listed in implement catalogues by 1895. One of the earliest patents for a disk plow was secured by M. A. and I. M. Cravath, Bloomington, Illinois. J. K. Underwood, D. H. Lane, and M. T. Hancock made improvements on the disk plow and made it practical. Since 1900, the development of the disk plow has followed trends similar to that of the moldboard plow.
Influence of the Plow on Man. When man grasped a crooked stick and began to till the soil, he took his first step toward civilization. With each phase in the development of the plow, there has been a corresponding advance in civilization. A study of the history of mankind shows that it is possible to have culture without techniques, but there is no viable culture without the plow. In the beginning, one man, even though he gave all his time and energy to the task, could till only a small acreage. Later, animal power was applied and the acreage per man was increased. Now, with the large amount of mechanical power available, the acreage per man has been very materially increased. Thus, man can now produce more foodstuff than is necessary for his own sustenance and can furnish food to many who are working at other tasks. Hence, we can say that the plow is the foundation of civilization. In the production of all kinds of crops and in the preparation of a seedbed for them, the plow is the first tool used and it is thus the basic tool of the farm. With the plow the ground is broken and pulverized into small particles; trash on the surface may be left on the surface or completely covered. One not familiar with the nature of the soil, the influence of water, air, and temperature upon its physical condition, and the action of the plow upon it may think that the plow is a very simple tool, requiring very little adjustment and practically no care at all. But those who are familiar with soil conditions and the plow adjustments necessary to obtain the best results know that the plow is the most important and complete tool on the farm, requiring the consideration of more factors for proper adjustment than does a gas engine.
Requirements of Tillage. A thoughtful analysis of the objects of tillage given in the following paragraph shows that a number of definite benefits are obtained by good plowing. The whole premise of high-yield crop production is based on the stirring of the soil with some type of implement, usually a plow, to provide a well-pulverized seedbed. In low-rainfall areas, such as Montana, the Dakotas, and the western edge of the Great Plains, many farmers stir the subsurface without turning under and burying the crop residue. This reduces wind erosion. Experiments have shown that in areas receiving an annual rainfall of 20 inches or more, plowing is necessary to maintain crop yields. Certain soil types, like the heavy clay, are not adaptable to plowless farming because of their texture. Under humid conditions, unless the crop residue is well buried, insects and plant diseases build up and reduce yields. A soil well pulverized by plowing will absorb rainfall and retain moisture for crops, while the unplowed soil will lose most of the rainfall by runoff. Pulverizing the soil aerates it and enhances the activity of microorganisms and bacteria, causing rapid oxidation and decay of crop residues. Stirring the soil is an aid to nitrification and the liberation of plant nutrients within the soil.
In the preparation of the seedbed, it is necessary to keep in mind some of the benefits to be derived from such an operation. With the plow we strive to accomplish the following results:
1. To create a deep seedbed physically, chemically, and biologically fitted to the growth of crops
2. To add humus and fertility to the soil by covering and burying crop residues and manures so they are incorporated in the soil
3. To prevent and destroy weeds or other unwanted vegetation
4. To leave the soil in such condition that air will circulate freely
5. To leave the soil in such condition as to retain moisture from rain
6. To destroy insects, as well as their eggs, larvae, and breeding places
7. To leave the surface in a condition to prevent erosion by winds
Organic and Stubble-mulch Tillage. Advocates of the plow method of soil tillage are not, at the present time, ready to discard the plow completely for the organic and stubble-mulch methods. The plow farmers do admit that the addition of organic matter to the soil is beneficial in many ways and that the soil is protected by certain amounts of vegetative mulch from water and wind erosion. The soil is protected when crop residue is left on the surface, but the highest yields are obtained when the residue is cut up and worked into the soil. However, the addition of large volumes of crop residue to certain soils appears to disturb the action of microorganisms and retard natural nitrification. Under some conditions, this can be counteracted by the addition of extra amounts of nitrogenous fertilizers. Research programs on methods of handling crop residues, under way in several states, should be carefully watched for proven recommendations.
Kinds of Tillage Equipment. Tillage equipment can be divided into two general classes, namely, (1) primary tillage equipment, and (2) secondary tillage equipment.
Equipment that is used to break deeply and loosen the soil to prepare a suitable seedbed may be considered as primary