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.