From what has been said in this brief description of soil treatment and soil improvement, it is evident that one must live with his soil for some time in order to understand it and to be able intelligently to correct its deficiencies, overcome its weaknesses and make it capable of supporting plants which are desirable from the owner's point of view. In the great majority of cases, the improvement process, while a slow one, is far from hopeless and almost any soil that is not extremely sandy or clayey can be so intelligently treated as to make it productive. _Cultivation._--Any discussion of soil treatment is not complete without mention of cultivation. Intelligent cultivation is an essential factor in securing adequate crops. It is interesting to recall that the word "manure," which has come to mean fertilization or fertilizer, is derived from the Latin word "_manus_" meaning "hand" and implying "manipulation" of the soil, which we now call cultivation. Cultivation has been most frequently practiced as a method of destroying weeds, thereby making all of the available plant food subject to absorption by the roots of the desired plants and not by the intruders we call weeds. Cultivation does more than destroy weeds, however. It opens up the soil so that air containing atmospheric nitrogen can penetrate it and so that the bacteria requiring air for their best growth may have it available. Furthermore, cultivation conserves moisture and is more essential during dry periods in the growing season than at any other time. We know that in entering the soil the rain water follows certain channels in and around the soil particles on its way to the subsoil. When the rain has ceased and the top layer of soil becomes dry, the tendency is for the water to work up through these same channels to the surface, where it evaporates. Cultivation, by breaking up these channels, or capillary tubes, checks the escape of moisture into the air. It creates a blanket of dry surface soil which insulates the soil moisture from the air above. The tendency of soil moisture to reestablish capillary methods of escape makes recultivation necessary from time to time in dry weather. Care must, of course, be taken that the cultivation is not harmful to roots of growing plants. If these roots are disturbed or destroyed through cultivation, more harm than good may result because of the damage to the root systems.