CHAPTEE IX 

 IRRIGATION AND DRAINAGE 



It is necessary to have the right degree of moisture in soils 

 to secure thfe best growth of plants. If it be too wet at certain 

 seasons or too dry at other times the growth of crops' is 

 retarded. Tillage will do much to control the amount of 

 moisture in garden soils. 



It is desirable and profitable under certain conditions to 

 have some system of drainage or of irrigation, or both. 



IRRIGATION 



It is not necessary to give any reason or argument for 

 irrigation of crops in sections where the climate is very dry. 

 Much work along that line is being done by the Reclamation 

 Service of the United States and by large corporations encour- 

 aged by certain favorable laws. 



Irrigation in Humid Regions. — Plant growth is de- 

 pendent upon the soil moisture being in just the right con- 

 dition throughout the growing season. Gardeners and farmers 

 are accustomed to depend upon rainfall to maintain the proper 

 soil moisture in humid climates. Every summer there are one 

 or more prolonged periods during which the rainfall is so slight 

 that crops of all kinds suffer greatly and plant growth is 

 checked. Indeed, plants are often killed by dry weather. It 

 is because of these drouthy periods in humid climates that 

 irrigation of some kind is necessary to maintain the best 

 growth of garden crops. When plants are compelled to suffer 

 from lack of moisture at any time, the loss is not merely during 

 the drouth, but the plants may never recuperate and regain 

 their full vigor or growth after the drouth is broken. To 

 avoid both of these losses irrigation is often found advisable 

 and profitable. 

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