WATER SUPPLY FOR CROPS. 13 



planted, and the plant tilled until grown. Fertility will 

 induce a fair growth even if seed and tillage arc defective, 

 but this can only be a partial substitute for the failure of 

 other conditions. However good the seed may be, and 

 though planted on a kindly soil, with the most careful tillage 

 and an abundant supply of the elements of plant-food in the 

 right proportions, yet if the supply of moisture be either 

 largely deficient or excessive, our efforts will meet with 

 disappointment ; for while, other conditions being favorable, 

 crops will grow on a scanty or excessive amount of water, 

 yet such growth is sickly and feeble compared with what it 

 would be with a Avell-regulated supply. 



If, then, we recognize that the supply of water is one of 

 the essential conditions of successful agriculture, and that 

 it is, to a large extent, under our control, it becomes a 

 matter of vital importance to the farmer to understand the 

 extent of his powder and to exercise it to his greatest ad- 

 vantage. Water covers nearly three-fourths of the surface 

 of the earth ; it also is present in the air, soil and rocks ; it 

 furnishes a large part of the weight of all living organisms, 

 both animal and vegetable ; it is also present in most sub- 

 stances which yve call dry, and even in many saline sub- 

 stances, in the form of water of crystallization. 



Water has the power of absorbing heat, and of parting 

 with an equal amount as it cools. It is this power which 

 keeps the wet soil cold in spring, and the sun warms it so 

 slowly that he nearly reaches his summer solstice before 

 steady warm weather prevails. In autumn the water helps 

 to retain the heat long after our part of the earth has turned 

 from the sun's direct rays. Thus a w^et spring is colder 

 than a dry one, and a wet season in autumn is, to a certain 

 extent,- a protection from frosts. The close proximity of 

 large bodies of water is a great protection from early frosts, 

 because they absorb and hold heat, which they give off 

 slowly during cold nights, and the vapor arising from the 

 water checks the radiation of heat. Water forms from 20 to 

 90 per cent, of the weight of growing vegetation. Plants 

 live and grow only by the aid of water, which dissolves 

 their natural food and enables them to assimilate it. To 

 accomplish this, plants must have a liberal supply of water 



