BUEEAU OF SOILS. 487 



immense accumulation of silts and loams forming the soils and sub- 

 soils of the region. Nowhere else in the world, so far as known, are 

 there so extensive accumulations of subaerial deposits as in the cen- 

 tral plains, and the accumulation is due primarily to that subterra- 

 nean movement of the waters which to-day renders the silt loams 

 more j^roductive than they would be if watered only by the meager 

 local rainfalL 



Under the modern view of the suborganic and dynamic character 

 of soils the chief factor of continuous activity is the circulating soil 

 water, which maintains appropriate texture in the soil body, passes 

 thence into the plants carrying materials for growth in solution, 

 and finally returns through transpiration to the condition of aqueous 

 vapor in the atmosphere. Now, the investigations have shown that 

 in productive regions there are two sources for the soil water, i. e., 

 (1) rainfall and (2) the store of ground water accumulated from the 

 rainfall of previous years and nongrowing seasons. Throughout the 

 greater part of the United States the rainfall of the growing season 

 does not suffice to ^ roduce crops, and cropping succeeds only as the 

 growing plants draw on the accumulated store of moisture, which is 

 generally equivalent in quantity to the rainfall of several years; in 

 fact, without this store farming, especially during dry seasons, would 

 frequently fail, so that it may be viewed as the a^icultural capital 

 of the country. To this important resource the soil-water investiga- 

 tions have been extended during recent months, with the object of 

 ascertaining (1) the quantity of ground water within reach of 

 capillarity and (2) the changes in quantity attending settlement and 

 cultivation. Generally the best indication of the ground-water level 

 (i. e., the level at which the subsoil and underlying rocks are satu- 

 rated) is afforded by wells and springs; and a census of representa- 

 tive wells and springs in every county in the United States was 

 undertaken through correspondence. Some 80,000 schedules "were 

 sent out to trustworthy correspondents of the department, and most 

 of these were filled out and returned. The data are still in process of 

 tabulation; yet the indications are clear that throughout much of 

 the country settled for a quarter century or more there has been a 

 decided lowering of the ground-water level, with of course a corre- 

 sponding increase in danger of crop loss through drought. Thus, in 

 Michigan the mean water level in 794 wells lowered 2.2 feet during 

 an average period of 18 years; in Minnesota the average lowering 

 of water in 920 wells was 3.45 feet during 14 years; in Iowa the 

 lowering in 1,160 wells averaged 3.6 feet in 21 years. The mean rate 

 of lowering of the ground-water level indicated by the wells in the 

 three States is 0.18 foot per year, or 4.5 feet during a quarter century. 

 The facts brought out by the inquiry serve to emphasize the im- 

 portance of so improving agriculture as to utilize and conserve on 

 each farm all the water received by it during the year. 



NEED OF LARGER APPROPRIATION FOR THE BUREAU OF SOILS. 



It has been some six or eight years since the appropriations for the 

 Bureau of Soils have been materially increased. During this time 

 the work has increased in volume and importance and in recognition 

 and appreciation by the people. The demands for the extension of 

 the work of the bureau are large and insistent, and I feel it my duty 



