IRRIGATION 
73 
be conducted to the garden by gravity, so there would he 
no expense for pumping. In many more instances a lift 
of 5 to 15 feet would put the water on land admirably 
adapted to garden crops. Near the cities water can usu- 
ally be secured at reasonable prices, and at some places 
for as low as 4 or 5 cents a thousand gallons. The late 
W. W. Rawson, the well-known New England gardener, 
claimed that an intensive grower could well afford to 
pump water at a cost of 10 cents a thousand gallons. If 
it were a matter of saving a crop from almost total loss 
it might pay to use water at double this cost. 
1 17. Functions of water. — Before entering into a prac- 
tical discussion of the subject of irrigation the student or 
the reader should fully realize what an important part 
water plays in the growth of plants. (1) It is a powerful 
solvent of plant foods. No matter how fertile a soil may 
be naturally, or how much manure or fertilizer may be 
added, such foods are valueless without water to dissolve 
them. Both stable manures and fertilizers often fail to 
give increased yields because of insufficient soil moisture. 
(2) Water not only serves as a solvent, but it holds in 
solution organic acids which are more powerful solvents 
than water alone. (3) Water is essential to the life of 
friendly bacteria. (4) Water serves as a vehicle in the 
distribution of plant foods in the soil. 
Its functions in the plant are equally important. (1) 
Water enters largely into the composition of all garden 
products. Many vegetables contain over 90 per cent of 
water. (2) W r ater is also a medium in the conveyance of 
food in the plant, so that enormous quantities transpire 
from the leaves. Several hundred pounds of water are 
required to produce every pound of dry matter. It is 
claimed that a well-developed hill of cucumbers will use 
half a barrel of water in three days. (3) The transpira- 
tion of water has an important relation to the fixation of 
carbon from the atmosphere. 
