332 SYSTEMS OF PERMANENT AGRICULTURE 



language of the Bureau of Soils, " it is worth from $i to $3 an acre," 

 which also covers 45,770 acres of land in Prince George County, 

 adjoining the District of Columbia, where it " can be bought for 

 $1.50 to $5 an acre, even within a few miles of the District 

 line," until this Leonard town loam, which, according to Whit- 

 ney's latest decision (Bureau of Soils Bulletin 55, page 116, Febru- 

 ary, 1909), " is a valuable upland soil of Maryland and Virginia; 

 the surface is slightly rolling, the drainage in most areas good, and 

 altogether the land is well suited to general farming"; until this 

 land which, according to the analyses of the Bureau of Soils 

 (Bulletin 54, page 19), contains in 2 million pounds of the surface 

 soil only 160 pounds of total phosphorus and 1000 pounds of total 

 calcium; that is, sufficient total phosphorus and total calcium 

 in the plowed soil of an acre for about 8 crops of clover, with such 

 yields as we can and do produce on our best-treated land in good 

 seasons (4 tons in 2 cuttings), until these impoverished lands 

 surrounding the National Capital have been rehabilitated and 

 changed in value from $1.50 to $150 an acre, by crop rotation, or 

 even by live-stock farming without the purchase of plant food in 

 feed or fertilizers, until these results have actually been accom- 

 plished, the student of agriculture is earnestly warned against 

 accepting any predictions that the farmers of Kansas or of any 

 other states are actually enriching their soils because they are 

 practicing live-stock farming to a greater or less extent. The 

 student is urged to have faith in the exact data of scientific inves- 

 tigations, such, for example, as those conducted for more than 60 

 years at Rothamsted, England, and for about 30 years at Urbana, 

 Illinois, and at State College, Pennsylvania, full records of which 

 are given in the following pages. 



Of course the small commercial countries of Europe which retain 

 practically all of their own fertility and import much more in 

 food stuffs and fertilizers can markedly enrich their soils, just as 

 some of our small states can build up some small areas of culti- 

 vated lands; but as the average yield of corn in the great state 

 of Georgia is only n bushels per acre, so the average yield of wheat 

 on the " black soils " of Russia, for the 20 years, 1883 to 1902, is 

 8 bushels per acre, and as a rule this land lies fallow every third 

 year. The following comment is recorded on page 27 of Bulletin 42 



