SPRAY IRRIGATION". 5 



justifies the farmer in using larger amounts of fertilizers. Truckerg 

 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 light 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 applied 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. 



V 



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 3 inches 

 per irrigation. Truck and citrus growers in the arid regions apply 

 more water than those in the humid region, probably because of a 



