"Practically four-fifths of the oat crop of the United States is produced in the thirteen States extending from New York and Pennsylvania westward to North Dakota, South Dakota, Nebraska, and Kansas. Each of these States annually devotes more than a million acres to oats. The average yield in the six northernmost States, New York, Michigan, Wisconsin, Minnesota, North Dakota and South Dakota, is 31.68 bushels to the acre, while their total production is lightly less than one-third of the oat crop of the country. The average yield of the other seven States, Pennsylvania, Ohio, Indiana, Illinois, Iowa, Nebraska, and Kansas, is only 29.23 bushels to the acre, yet they produce more than half of the entire crop. The difference in yield of nearly two and one-half bushels to the acre between these two groups of States is due largely to the fact that the climatic conditions of the northern group are better suited to the production of the crop. There is no material difference in soil preparation or other influencing factors. Oats are grown in the corn belt, which includes the States of the second group, largely because a small-grain crop is needed in the rotation and because the grain is desired for feeding to work stock. Spring wheat is seldom satisfactory in this district, and winter crops often do not fit well into a rotation which ordinarily includes corn, a small grain, and grass, Under these conditions oats are generally grown as the best crop between corn and grass. This is particularly true in Illinois and Iowa, the two State producing the greatest quantity of both corn and oats."--Introduction (p.7)