SOILS AND ALKALI. 
13 
sible to select a single sample of soil that will fairly repre¬ 
sent a field; when to this is added the small quantity 
taken for analysis, as compared with, say even one acre, 
the difficulties are increased. 
The soil of an acre of land taken to the depth of one 
foot will weigh about 4,000,000 pounds. About 1-10 of 
one per cent, is the usual limit of chemical analysis in 
this kind of work. One thousand pounds of guano 
would contain about 150 pounds of nitrogen, 150 pounds 
of phosphoric acid and 30 pounds of potash, making 
330 pounds of fertilizing ingredients; then we have 
4-0 00000 = 12 T 00 or w ithin the limits of chemical analysis. 
It is possible that the droppings of a bird flying over 
it, if it happens to be in the sample analyzed, would 
make an unfair statement of the chemical analysis. If 
it were the place to discuss it, there are many questions 
that the chemical analysis of a soil cannot answer. 
%j 
The following samples of soil were analyzed. The 
method of analysis is described in Bulletin No. 10, Di¬ 
vision of Chemistry, of the Department of Agriculture : 
No. 1—Arkansas Valley Experiment Station, from 
the orchard—sandy soil. 
No. 2—Arkansas Valley Experiment Station, from 
nursery—clay loam. 
No. 3—Arkansas Valley Experiment Station, from 
farm—adobe. 
No. 4—Yuma, Colorado—adobe land. 
No. 5—College farm, average of two places. 
No. 6—College garden, average of two places—beets 
grown on soil, not manured. 
No. 7—College garden—tobacco land. 
No. 8—College garden—beets grown, manured. 
No. 9—San Luis Experiment Station—sandy, gravelly 
loam. 
No. 10—San Luis Experiment Station—sandy, gravelly 
loam. 
No. 11—San Luis Experiment Station—sandy, gravelly 
loam. 
