The subsurface packer invented by Campbell is [shown in Figure 83—not shown—ed.]. The wheels of this machine eighteen inches in diameter, with rims one inch thick at the inner part, beveled two and a half inches to a sharp outer edge, are placed on a shaft, five inches apart. In practice about five hundred pounds of weight are added.
This machine, according to Campbell, crowds a one-inch wedge into every five inches of soil with a lateral and a downward pressure and thus packs firmly the soil near the bottom of the plow-furrow. Subsurface packing aims to establish full capillary connection between the plowed upper soil and the undisturbed lower soil-layer; to bring the moist soil in close contact with the straw or organic litter plowed under and thus to hasten decomposition, and to provide a firm seed bed.
The subsurface packer probably has some value where the plowed soil containing the stubble is somewhat loose; or on soils which do not permit of a rapid decay of stubble and other organic matter that may be plowed under from season to season. On such soils the packing tendency of the subsurface packer may help prevent loss of soil water, and may also assist in furnishing a more uniform medium through which plant roots may force their way. For all these purposes, the disk is usually equally efficient.
Sowing
It has already been indicated in previous chapters that proper sowing is one of the most important operations of the dry-farm, quite comparable in importance with plowing or the maintaining of a mulch for retaining soil-moisture. The old-fashioned method of broadcasting has absolutely no place on a dry-farm. The success of dry-farming depends entirely upon the control that the farmer has of all the operations of the farm. By broadcasting, neither the quantity of seed used nor the manner of placing the seed in the ground can be regulated. Drill culture, therefore, introduced by Jethro Tull two hundred years ago, which gives the farmer full control over the process of seeding, is the only system to be used. The numerous seed drills on the market all employ the same principles. Their variations are few and simple. In all seed drills the seed is forced into tubes so placed as to enable the seed to fall into the furrows in the ground. The drills themselves are distinguished almost wholly by the type of the furrow opener and the covering devices which are used. The seed furrow is opened either by a small hoe or a so-called shoe or disk. At the present time it appears that the single disk is the coming method of opening the seed furrow and that the other methods will gradually disappear. As the seed is dropped into the furrow thus made it is covered by some device at the rear of the machine. One of the oldest methods as well as one of the most satisfactory is a series of chains dragging behind the drill and covering the furrow quite completely. It is, however, very desirable that the soil should be pressed carefully around the seed so that germination may begin with the least difficulty whenever the temperature conditions are right. Most of the drills of the day are, therefore, provided with large light wheels, one for each furrow, which press lightly upon the soil and force the soil into intimate contact with the seed The weakness of such an arrangement is that the soil along the drill furrows is left somewhat packed, which leads to a ready escape of the soil-moisture. Many of the drills are so arranged that press wheels may be used at the pleasure of the farmer. The seed drill is already a very useful implement and is rapidly being made to meet the special requirements of the dry-farmer. Corn planters are used almost exclusively on dry-farms where corn is the leading crop. In principle they are very much the same as the press drills. Potatoes are also generally planted by machinery. Wherever seeding machinery has been constructed based upon the principles of dry-farming, it is a very advantageous adjunct to the dry-farm.
Harvesting
The immense areas of dry-farms are harvested almost wholly by the most modern machinery. For grain, the harvester is used almost exclusively in the districts where the header cannot be used, but wherever conditions permit, the header is and should be used. It has been explained in previous chapters how valuable the tall header stubble is when plowed under as a means of maintaining the fertility of the soil. Besides, there is an ease in handling the header which is not known with the harvester. There are times when the header leads to some waste as, for instance, when the wheat is very low and heads are missed as the machine passes over the ground. In many sections of the dry-farm territory the climatic conditions are such that the wheat cures perfectly while still standing. In such places the combined harvester and thresher is used. The header cuts off the heads of the grain, which are passed up into the thresher, and bags filled with threshed grain are dropped along the path of the machine, while the straw is scattered over the ground. Wherever such a machine can be used, it has been found to be economical and satisfactory. Of recent years corn stalks have been used to better advantage than in the past, for not far from one half of the feeding value of the corn crop is in the stalks, which up to a few years ago were very largely wasted. Corn harvesters are likewise on the market and are quite generally used. It was manifestly impossible on large places to harvest corn by hand and large corn harvesters have, therefore, been made for this purpose.
Steam and other motive power
Recently numerous persons have suggested that the expense of running a dry-farm could be materially reduced by using some motive power other than horses. Steam, gasoline, and electricity have all been suggested. The steam traction engine is already a fairly well-developed machine and it has been used for plowing purposes on many dry-farms in nearly all the sections of the dry-farm territory. Unfortunately, up to the present it has not shown itself to be very satisfactory. First of all it is to be remembered that the principles of dry-farming require that the topsoil be kept very loose and spongy. The great traction engines have very wide wheels of such tremendous weight that they press down the soil very compactly along their path and in that way defeat one of the important purposes of tillage. Another objection to them is that at present their construction is such as to result in continual breakages. While these breakages in themselves are small and inexpensive, they mean the cessation of all farming operations during the hour or day required for repairs. A large crew of men is thus left more or less idle, to the serious injury of the work and to the great expense of the owner. Undoubtedly, the traction engine has a place in dry-farming, but it has not yet been perfected to such a degree as to make it satisfactory. On heavy soils it is much more useful than on light soils. When the traction engine works satisfactorily, plowing may be done at a cost considerably lower than when horses are employed.
In England, Germany, and other European countries some of the difficulties connected with plowing have been overcome by using two engines on the two opposite sides of a field. These engines move synchronously together and, by means of large cables, plows, harrows, or seeders, are pulled back and forth over the field. This method seems to give good satisfaction on many large estates of the old world. Macdonald reports that such a system is in successful operation in the Transvaal in South Africa and is doing work there at a very knew cost. The large initial cost of such a system will, of course, prohibit its use except on the very large farms that are being established in the dry-farm territory.