WEATHER IN CRANBERRY CULTURE 63 



Rotating-head s\-stems are better for cranberry service than pipe-nozzle systems 

 because they are simpler, are less expensive to install and maintain, are less in 

 the way of bog operations, and are troubled less by a little sand in the water. 



In arranging for sprinkling equipment, each bog is a special engineering prob- 

 lem. The shape and size of the bog, the spacing of the ditches, the source of 

 water and the amount available, must all be considered to determine the best 

 spacing of the sprinklers. The first cost of the installation and the cost of its 

 operation and maintenance over a term of years must also be considered. Medium- 

 pressure heads (say with 70 pounds pressure at the pump and 40 pounds at the 

 heads), moderately spaced (perhaps 8 to an acre), are best on large bogs (8 acres 

 or more), for they use less water (64 gallons a minute to the acre) and require a 

 much less costly power plant and pump for the ground covered than do high- 

 pressure heads. High-pressure heads (90 pounds pressure at the pump and 60 

 pounds at the heads), about 5 to an acre, are advisable for bogs of 3 acres or less 

 because of a saving in pipe with little difference in the cost of the power plant and 

 pump. These heads put about 75 gallons a minute on an acre. The lines of pipe 

 leading to the sprinklers should be laid on cross-pieces over the ditches to be out 

 of the way. Main pipe lines may be of galvanized or cast iron or of wood, the 

 latter being preferred on the Pacific coast. Galvanized piping is best for the 

 laterals. Secondhand automobile engines and centrifugal pumps are economical 

 and satisfactory in such systems.*^ 



The method of operating sprinklers for frost protection has been to start them 

 before the temperature has fallen below 40° F. and keep them going till it is well 

 above freezing the next morning. It probably would be helpful also to wet the 

 ground well by sprinkling several hours in the late afternoon and evening before 

 a severe frost. Practices will vary with the temperature of the water used. 



About 225 acres of cranberry vines on the Pacific coast are protected with 

 sprinklers. They are not used at all on the bogs of New Jersey and Wisconsin. 



Resanding 



As Cox has shown, s'^ the temperature of the top soil and minimum tempera- 

 tures of the air over it vary with the character of the soil and its covering; and a 

 coat of sand on a cranberry bog protects the vines from frost considerably by 

 giving up heat to the air during the night, sand being a much better conductor 

 than peat.88 Resanding covers moss and dilutes and buries accumulations of 

 fallen cranberry leaves (see above) and other organic matter on the bog floor and 

 so tends to maintain the conductivity of the surface soil. Resanding should not 

 be delayed enough to allow large amounts of such material to collect under the 

 vines, especially on bogs that cannot be protected with water, for a lot of it 

 covered with sand will largely insulate that sand from the soil below. Strictly 

 dry bogs, especially those with fairly thick vines, should be resanded moderately 

 every year to keep this material diluted, for it accumulates rapidly where none of 

 it is ever removed with water. Dry bogs should not be resanded in the fall, for 

 the vines waterkill more readily after disturbance; they should be sanded very 

 early in the spring so that the sand may pack before frosts get dangerous, for 

 sand conducts heat better when it is packed than when it is'loose.^^ 



8^Much of this information comes from Sales Agent George N. Barrie of the Skinner System 

 of Irrigation and Manager Emile C. St. Jacques of the Hayden Cranberry Separator Manufac- 

 turing Company. 



S^Cox, op. cit., pp. 8, 9, 41, 52, 63-64, 76-77, and 80-83. 



^^Geiger, op. cit., pp. D6-D8. 



^^Geiger, op. cit., pp. D6-D8 



