

SPRAY IRRIGATION. 5 
justifies the farmer in using larger amounts of fertilizers. Truckers 
near Philadelphia are using profitably as high as 50 tons of manure 
per acre each year. Therefore, proximity to manure markets is a 
factor of importance to be considered by the prospective spray irri- 
gator. 
FARM CONDITIONS ADAPTED TO SPRAY IRRIGATION. 
Where economic conditions are favorable to the adoption of spray 
irrigation, the most important question then becomes one of an ade- 
quate water supply, which will be considered under a separate 
heading. : 
Spray irrigation can be practiced to advantage on both hght and 
heavy soils. By this method it is possible to apply evenly to sandy 
soils the small quantities of water which such soils will retain, with- 
out the loss of water by percolation which might occur with other 
methods. It is possible also to apply to heavy clay soils the small 
quantities of water required to soften such soils when they have 
baked after rains, and to apply water no faster than the soil can ab- 
sorb it, thus preventing loss by surface run-off. 
Lands to be irrigated should be drained as completely as possible 
of excess moisture. Many tile-drained fields are the most respon- 
sive to crops under spray irrigation. 
Spray irrigation is practically independent of the topography of 
the field and can be apphed to land too rolling or rough for surface 
methods. It is, therefore, adaptable to the irrigation of side hills on 
which soils tend to wash or erode. 
AMOUNT OF WATER REQUIRED FOR SPRAY IRRIGATION. 
As yet, the available knowledge on the amount of water required 
for spray irrigation is limited, because of the comparative newness 
of the method and the lack of actual records on plants under a time 
test. The writer, however, has made estimates in several cases by 
recording the number of hours a plant of known capacity has been 
operated with effective results. In the humid regions amounts not 
exceeding one-fourth inch in depth often are considered a sufficient 
application to seed beds and young vegetables, while in the case of 
maturing garden crops and strawberries one-half to 1 inch may be 
applied. It is probable that truckers in the humid region do not 
use more than 6 inches in a growing season and in many seasons 4 
inches or less will supplement the rainfall sufficiently. More water 
is required for sandy soils than for clay. A crop like the spray- 
irrigated citrus groves of Florida may require as much as 8 inches 
per irrigation. Truck and citrus growers in the arid regions apply 
more water than those in the humid region, probably because of a 

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