34 MASSACHUSETTS HORTICULTURAL SOCIETY. 



its gardens and the subsistence of its popnlation to the practice of 

 irrigation. In this countr}', too, the first Spanisli invaders of 

 Mexico and Peru found a ver}^ elaborate sj'stem of aqueducts in use 

 by the Aztecs, which has since fallen into decay in consequence of 

 the neglect of the miserably indolent people who have now posses- 

 sion of those countries. 



It is not, however, the purpose of this paper to discuss the in- 

 teresting history of irrigation, or to show, as might be done, that its 

 practice is one of the best signs of enlightened industry and civi- 

 lization ; but to call attention to some of the practical questions 

 connected with it in New England today. 



These questions naturally present themselves in the following 

 order, viz. : 



1st. The amount of water required for successful irrigation. 



2d. The sources of supply. 



3d. The means of application, and of distribution of the water 

 over the land. 



4th. The advantages and limits of irrigation. 



1st. The Amount of Water Required. The amount of water 

 needed b}^ vegetation during the growing season, for a full crop of 

 most kinds of useful or ornamental garden products, is variously 

 estimated by different authorities ; the requirements themselves are 

 ver}' different under different circumstances ; a loose, sandy soil 

 will require much more water to irrigate it than a retentive clay or 

 a peaty intervale ; and some kinds of vegetables, like celery and 

 cauliflowers, require much water ; while man}^ others, like corn, 

 beans, and the grains, will endure considerable drought without in- 

 jmy. Much also depends on the temperature of the air, and the 

 velocity of the wind, as well as on the more evident and important 

 considerations of rainfall and atmospheric humidit}'. 



In general, however, it may be assumed that, in the warm, grow- 

 ing months of May, June, July, August, and September, most 

 vegetation requires an inch in depth over the entire surface of the 

 land every five days. This is, of course, only an average amount ; 

 sometimes less than half this amount will be needed, and some- 

 times much more. 



This amount estimated as needed by our gardens, would be 

 equivalent to six inches per month of rainfall ; if we compare this 

 amount with the actual rainfall, we shall arrive at an idea of what 

 is to be supplied artificially'. 



