To summarize, the apparent increase in productivity and plant-food content of dry-farm soils can best be explained by a consideration of these factors:  (1) the intrinsically high fertility of the arid soils; (2) the deep feeding ground for the deep root systems of dry-farm crops; (3) the concentration of the plant food distributed throughout the soil by the upward movement of the natural precipitation stored in the soil; (4) the cultural methods of dry-farming which enable the weathering agencies to liberate freely and vigorously the plant-food of the soil grains; (5) the small annual crops; (6) the plowing under of the header straw, and (7) the activity of bacteria that gather nitrogen directly from the air.

Methods of conserving soil-fertility

In view of the comparatively small annual crops that characterize dry-farming it is not wholly impossible that the factors above discussed, if properly applied, could liberate the latent plant-food of the soil and gather all necessary nitrogen for the plants.  Such an equilibrium, could it once be established, would possibly continue for long periods of time, but in the end would no doubt lead to disaster; for, unless the very cornerstone of modern agricultural science is unsound, there will be ultimately a diminution of crop producing power if continuous cropping is practiced without returning to the soil a goodly portion of the elements of soil fertility taken from it.  The real purpose of modern agricultural researeh is to maintain or increase the productivity of our lands; if this cannot be done, modern agriculture is essentially a failure.  Dry-farming, as the newest and probably in the future one of the greatest divisions of modern agriculture, must from the beginning seek and apply processes that will insure steadiness in the productive power of its lands.  Therefore, from the very beginning dry-farmers must look towards the conservation of the fertility of their soils.

The first and most rational method of maintaining the fertility of the soil indefinitely is to return to the soil everything that is taken from it.  In practice this can be done only by feeding the products of the farm to live stock and returning to the soil the manure, both solid and liquid, produced by the animals.  This brings up at once the much discussed question of the relation between the live stock industry and dry-farming.  While it is undoubtedly true that no system of agriculture will be wholly satisfactory to the farmer and truly beneficial to the state, unless it is connected definitely with the production of live stock, yet it must be admitted that the present prevailing dry-farm conditions do not always favor comfortable animal life.  For instance, over a large portion of the central area of the dry-farm territory the dry-farms are at considerable distances from running or well water.  In many cases, water is hauled eight or ten miles for the supply of the men and horses engaged in farming.  Moreover,