More plowing is done in the spring just before planting spring and summer crops than at any other time, excepting in localities that plant large areas of winter grain and truck. This spring plowing should be done early, for the spring plowing tends to dry the loosened soil somewhat and allows it to become warm at an earlier date, and at the same time the loosened soil tends to hold water in the lower soil for future use by the crop and allows the soil to take in spring rains more readily. If a cover crop or green manure crop is to be turned under in the spring it should be done early so as to prevent the crop to be turned under from pumping too much water out of the soil and thus interfering with the growth of the crop for which the land is being prepared. There are some particular advantages to be gained by fall plowing in heavy soils: Immediately after harvest the land is usually dry and easy to work. The soil plowed at this time and left rough is acted upon physically by frost which pulverizes it, and chemically by rain and air which renders plant food available. Insects are turned up and exposed to frost and birds. A great number of weeds are destroyed and the land is more easily fitted for crops in the spring. Fall plowing should be done as early as possible, especially in the dryer regions, to catch all water possible. It is not advisable to plow sandy soils in the fall lest plant food be washed out of them. When possible a cover crop should be put on fall plowed land where there is likely to be loss of plant food by leaching. BARE FALLOW The term "fallowing" is sometimes applied to the operation of plowing, and sometimes the land is left bare without a crop sometime after plowing; this is called "bare fallowing" the land. Bare fallowing should not be practiced on all soils. It is adapted: To dry climates and dry seasons where it is desirable to catch and save every possible drop of rainfall, and where plant food will not be washed out of the exposed soils by rains. To heavy clay lands. To lands that are foul with weeds and insects. To sour soils which are sweetened by exposure to air and rain. Light sandy soils should not be subjected to bare fallow unless they are very foul with weeds. They should always be covered with a crop to prevent loss of plant food by leaching. CHAPTER XII HARROWING AND ROLLING HARROWING After spading or plowing the next operation in the preparation of the soil is generally raking, harrowing or dragging. The objects of these operations are: To break lumps and clods left by the plow and spade and to further pulverize the soil. Harrowing and raking aid in controlling soil ventilation, and put the soil in better condition to absorb moisture. They check the loss of moisture by making a mulch of fine loose earth on the surface. The harrow and rake destroy the weeds. The harrow brings about conditions favorable to the even distribution of seeds.