SEEDING, PLANTING AND YIELDS 135 is broken up by subsequent tillage ; or if the crop is not tilled, as the cereal grains, the seed-bed disappears by the action of the elements and the natural settling together of the soil. The seed-bed is therefore only an epoch in the care of the field.
The comminuting tillage tools leave the ground loose and more or less open. In this loose earth the seed is readily incorporated. But the earth may be too loose to promote the best germination. In such cases the roller is used to compact the earth. The soil-grains are then settled about the seeds, and the subsurface moisture passes up from grain to grain or through the small cavities, and supplies the seed. This moisture is on its way toward evaporation into the air ; therefore it is well to break up the com pact surface by tillage, as soon as the plants are well established, in order to prevent the further loss of moisture, particularly if it is the case of a spring-sown crop. The com mon practice of tramping on the row in making garden hereby finds explanation; and it is probable that the custom of spatting the hill with the hoe in the steadfast old days when we planted corn by hand, had other merit than merely to mark the spot where we had dropped five kernels from a bed-ticking bag.
The quantity to sow.
The reader will want to know how much seed of the various things is required for an acre: This information was once easy to give, when fields were small and every one followed the cus tom of his father or his neighbor. But now we plant in hills at all distances, or drills at all distances, or semi-broadcast at no distances, and we grow crops for more purposes than were ever dreamed of in the old philosophy. The tables, therefore, represent Fig. 205. A six-foot seeder, with grass either averages or extremes, and the person who is looking for seed attachment. precise direction is likely not to find it, and he is told that it all depends on conditions, and as likely as not he does not know what the conditions are. However, a table has been compiled from good sources, and the reader is referred, for further information, to the articles on the special crops comprising the major part of this book ; from these sources the reader should be able to derive some help.