=The Effects of Agricultural Improvements.=—During the past half century great progress has been made in all the processes of agriculture. The methods of treating the soil, the types of grain and other produce grown, the machinery available for use in agriculture, and the general intelligence with which the lands are cultivated—all have vastly improved since our grandfathers’ day. [Sidenote: The increased yield of the soil.] The results are apparent in an increased production. At the time of the Civil War the yield of wheat throughout the United States averaged only nine to ten bushels per acre; today it is nearly double that figure. Good farms and good farmers are now producing twenty-five bushels of wheat to the acre, sixty bushels of corn, or six hundred pounds of cotton. Similar progress has been made in the raising of cattle and in dairying. This has been accomplished by the selection and breeding of improved stock. Year by year this improvement continues and it is certain that we have not yet nearly reached the limit of possibilities. On the highly fertilized lands of some European countries the wheat yield is as high as thirty or even forty bushels to the acre. In the case of root crops, fertilization of the land is an extremely important factor in production. [Sidenote: Our future possibilities.] One of the great present-day needs of American agriculture is a better and cheaper supply of nitrates for fertilizing the land and this has directed attention to the possibility of manufacturing nitrates in this country instead of importing them from abroad.[158]