IRRIGATION AND DRAWING. 



CHAPTER TV. 



IRRIGATION AND DRAINING. 



Irrigation might properly enough be classed under the 

 head of manures, for the materials which it provides are 

 not only food for plants, but they aid also in procuring it 

 from other sources. Water is of indispensable necessity to 

 vegetable life, and the great quantity of it demanded for 

 this purpose, is in most climates amply provided by nature 

 in the stores of rain and dew which almost every where 

 moisten the earth, and especially during the early growth of 

 vegetation when it is most required. In countries where 

 rain seldom or never falls, as in parts of South America, 

 Egypt and elsewhere, the radiation of heat from the sur- 

 face is so rapid under their clear skies, that excessive 

 deposites of dew, generally supply the plants with all the 

 moisture which they need. The same effect takes place 

 throughout most of the United States in our transparent 

 summer atmosphere, and it is to the presence of copious 

 dews on our rich well cultivated fields, that much of the 

 luxuriance and success is due, which has ever attended en- 

 lightened and judicious American husbandry. 



Besides the moisture that abounds in the atmosphere, but 

 which is not always available in rains and dews to the 

 desired extent for the wants of vegetation, and that which 

 imperceptibly ascends from remote depths in the earth and 

 administers to the support of plants; it is a practice coeval 

 with the earliest history of agriculture, to bring artificial 

 waters upon the cultivated fields, and make them contribute 

 to the support of the crops. In many countries this sys- 

 tem is indispensable to secure their maturity; for although 

 dews accomplish the object in a measure, they do not sup- 

 ply it in the quantity required to sustain a vigorous growth. 

 We find in looking to the practice of Egypt and the Barbary 

 States in Africa; of Syria, Babylon, nnd other places in 



