121 
ment which I have repeated many times both in my teaching and in my publication, 
to wit: 
"While all soils of high plant-food percentages are highly productive under all but 
very extreme physical conditions, the reverse is by no means true, since soils with 
low percentages may he highly productive if the relative proportions of the several 
ingredients he good and the soil mass deep." 
I have for some years carried on an investigation to determine the limits of dilution 
within which plants will do equally well in soils of high fertility (and plant food per- 
centages) when these are diluted with quartz sand. While not yet completed, this 
investigation lias already shown that a rich adobe (clay) soil, and an equally rich 
sandy soil, diluted to an extent of four to one, show equally good growth, hut that 
when in these soils the dilution reaches five to one development is quite slow and in 
a short season would mean a crop failure. The moisture content was in all these 
eases maintained at two-thirds the maximum water capacity of each diluted soil. 
Photographs show clearly that here the roots made up by their extension for the 
lack of concentration of the food supply; but at the dilution of one to five they were 
unable to make up the deficiency, at least within a reasonable time. Other things 
being equal, it is the proportion, then, between the several soil ingredients, quite as 
much as the absolute quantity at hand, that determines production. Incidentally, 
this experiment shows the wide variation of physical composition (from a soil con- 
taining 35 per cent of colloidal clay to one with only 8.75 per cent, and in the sandy 
soil from 7.6 per cent to 1.9 per cent) within which plants will do equally well, pro- 
vided the plant-food ingredients are rightly proportioned; and provided, also, that 
a proportionally large soil mass is available to each plant. 
In the foregoing discussion only the salient points of the bulletin in question have 
been taken up and their most obvious weaknesses briefly considered. To do more 
would involve the writing of a paper as long as the bulletin itself; and it is to be 
hoped that the matter will be taken up by others also. Thus, for instance, the 
Rothamsted station might have something to say regarding the singular interpreta- 
tion put upon the splendid work of Lawes and Gilbert. 
In conclusion, it seems to the writer that the verdict upon the main theses put 
forward so confidently in this paper must be an emphatic "Not proven!" 
R H. Forbes, of Arizona, read the following paper: 
Utility of Soil Surveys in the West. 
Soil survey as applied to western conditions naturally falls under two heads — (1) 
the classification, area determination, and mapping of the different mechanical 
grades of soils in a certain district, ranging from the finer and heavier soils through 
the most distinctive intermediate grades to the sandiest and lightest ones; and (2) the 
determination and portrayal of the water-soluble content of those soils, or, as it is 
commonly known, the alkali. 
With the first form of soil survey you are familiar here in the East, notably in con- 
nection with the extension of tobacco culture and truck gardening, but excessive 
accumulations of soluble salts, in part plant foods which, through very excess, have 
become plant poisons, the lurking underground enemy of the farmer, the migratory 
and ubiquitous alkali, are to most men in this assemblage probably (and fortunately) 
a rare curiosity. 
I can most quickly bring the value of soil and alkali survey work to a pioneering 
people before you by means of illustrations drawn from our own experience in the 
far Southwest with the results of this work. 
It was our good fortune some four years ago to be associated with the Bureau of 
Soils in a cooperative soil and alkali survey of Salt Kiver Valley. Our elder brothers 
in this undertaking finished the w T ork in due form, and it was finally placed before 
our people, affording them definite and extensive information regarding the land of 
their very recent adoption. It is safe to say that, since the publication of the maps 
depicting the location and nature of the different soil areas, a very large share of the 
real estate business of this district, especially of the new, unfarmed lands, has been 
guided by the information thus afforded; and they have often protected the pur- 
chaser and curbed the fervent imagination of the real-estate man. But the most 
interesting instance of the usefulness of this branch of the work just recently occurs 
in connection with the establishment of a great, new industry in that locality. I 
refer to the beet-sugar factory resulting jointly from the experimental work carried 
on for six years past by the Arizona Station and the business enterprise of some of 
our moving men. 
The results of cultural work indicated very clearly those types of soil which, under 
our climatic conditions, could produce satisfactory quality and tonnage of beets. This 
information, in connection with the soil maps of the survey, made it immediately 
