All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

266 All About Inventions —the cultivation of vegetables, fruit, and a wide selection of other produce. It is a significant fact that when a community rises in a new district which has been reclaimed for the growing of wheat, the cultiva- tion of the latter article immediately commences to diminish in its immediate vicinity. This influence is exerted over a wide radius around the new centre, because it is generally considered that the ground can be rendered more profitable to the owner by raising other commodities. Again, it must also be borne in mind that those who open up new territories, while diligent in working the ground for wheat, are quite satisfied with the bounteous yield given by Nature. The virgin soil is rich, and what the owner considers a fair return per acre is obtained. Thus, in the United States, where the greater part of the wheat is grown upon the prairie, the average yield is about 12 bushels per acre, while in Western Canada it is approximately 15 bushels per acre. This is the yield which Nature gives the farmer. The latter, on his part, makes no effort to assist Nature. He never attempts to replace a fraction of the nitrogenous content of the soil which is extracted and consumed by his crops. The result is that the land in time commences to become impoverished, and the yield per acre falls. Possibly many years may elapse before such a result is observed, but it must occur sooner or later. In some districts, where the soil is termed “ poor,” it takes place within five or six years ; in others, where the soil is rich, half a century may pass before deterioration sets in. We are so accustomed to the vast wheatfields of