So vitally important is a permanent soil mulch for the conservation for plant use of the water stored in the soil that many attempts have been made to devise means for the effective cultivation of land on which small grains and grasses are growing. In many places plants have been grown in rows so far apart that a man with a hoe could pass between them. Scofield has described this method as practiced successfully in Tunis. Campbell and others in America have proposed that a drill hole be closed every three feet to form a path wide enough for a horse to travel in and to pull a large spring tooth cultivator' with teeth so spaced as to strike between the rows of wheat. It is yet doubtful whether, under average conditions, such careful cultivation, at least of grain crops, is justified by the returns. Under conditions of high aridity, or where the store of soil-moisture is low, such treatment frequently stands between crop success and failure, and it is not unlikely that methods will be devised which will permit of the cheap and rapid cultivation between the rows of growing wheat. Meanwhile, the dry-farmer must always remember that the margin under which he works is small, and that his success depends upon the degree to which he prevents small wastes. Dry-farm potatoes, Rosebud Co., Montana, 1909. Yield, 282 bushels per acre. The conservation of soil-moisture depends upon the vigorous, unremitting, continuous stirring of the topsoil. Cultivation! cultivation! and more cultivation! must be the war-cry of the dry-farmer who battles against the water thieves of an arid climate. CHAPTER IX REGULATING THE TRANSPIRATION