336 DRY-FARMING 



to supply himself with all the water needed for the 

 homestead. Such reservoirs may already be found 

 in great numbers scattered over the whole western 

 America. As dry-farming increases their numbers 

 will also increase. 



When neither canals, nor springs, nor flood waters 

 are available for the supply of water, it is yet possible 

 to obtain a limited supply by so arranging the roof 

 gutters on the farm buildings that all the water that 

 falls on the roofs is conducted through the spouts 

 into carefully protected cisterns or reservoirs. A 

 house thirt}' by thirty feet, the roof of which is so 

 constructed that all that water that falls upon it is 

 carried into a cistern will yield annually under a 

 a rainfall of fifteen inches a maximum amount of 

 water equivalent to about 8800 gallons. Allowing 

 for the unavoidable waste due to evaporation, this 

 will yield enough to su])ply a household and some 

 live stock with the necessary water. In extreme 

 cases this has been found to be a very satisfactory 

 practice, though it is the one to be resorted to only 

 in case no other method is available. 



It is indispensable that some reservoir be provided 

 to hold the surface water that ma}' be obtained until 

 the time it may be needed. The water coming con- 

 stantly from a spring in summer should be applied 

 to crops onh' at certain definite seasons of the year. 

 The flood waters usually come at a time when plant 

 growth is not active and irrigation is not needed. 



