378 
EFFECTS OF IRRIGATION. 
Lombardy are not included in these estimates of the amount 
of water applied. Arrangements are concluded, and new 
plans proposed, for an immense increase of the lands fertilized 
by irrigation in France and Italy, and there is every reason to 
believe that the artificially watered soil of the latter country 
will be doubled, that of France quadrupled, before the end of 
this century. There can be no doubt that by these operations 
man is exercising a powerful influence on soil, on vegetable 
and animal life, and on climate, and hence that in this, as 
in many other fields of industry, he is truly a geographical 
agency.* 
and the Sesia, both because it is warmer, and because it transports a more 
abundant and a richer sediment than the latter streams, which are fed by 
Alpine icefields and melting snows, and which flow, for long distances, in 
channels ground smooth and bare by ancient glaciers, and not now con¬ 
tributing much earth or fine slime to their waters. 
* It belongs rather to agriculture than to geography to discuss the 
quality of the crops obtained by irrigation, or the permanent effects pro¬ 
duced by it on the productiveness of the soil. There is no doubt, how¬ 
ever, that all crops which can be raised without watering are superior in 
flavor and in nutritive power to those grown by the aid of irrigation. 
Garden vegetables, particularly, profusely watered, are so insipid as to be 
hardly eatable. Wherever irrigation is practised, there is an almost irre¬ 
sistible tendency, especially among ignorant cultivators, to carry it to 
excess; and in Piedmont and Lombardy, if the supply of water is abundant, 
it is so liberally applied as sometimes not only to injure the quality of the 
product, but to drown the plants and diminish the actual weight of 
the crop. 
Professor Liebig, in his Modern Agriculture , says: “ There is not to be 
found in chemistry a more wonderful phenomenon, one which more con¬ 
founds all human wisdom, than is presented by the soil of a garden or field. 
By the simplest experiment, any one may satisfy himself that rain water 
filtered through field or garden soil does not dissolve out a trace of potash, 
silicic acid, ammonia, or phosphoric acid. The soil does not give up to the 
water one particle of the food of plants which it contains. The most con¬ 
tinuous rains cannot remove from the field, except mechanically, any of 
the essential constituents of its fertility.” 
“ The soil not only retains firmly all the food of plants which is actually 
in it, but its power to preserve all that may be useful to them extends 
much farther. If rain or other water holding in solution ammonia, potash, 
and phosphoric and silicic acids, be brought in contact with soil, these sub- 
