220 Irrigation and Drainage 



In Italy these heavy and continuous irrigations stimulate 

 the grass to grow the year round, and in the vicinity of Milan, 

 where the irrigation canals are led through and beneath the 

 city, relieving it of all its sewage, this warm and highly ferti- 

 lizing water so stimulates the growth of grass that seven heavy 

 crops are taken from the ground each year, aggregating, accord- 

 ing to Baird Smith, 45 to 50 tons per acre, and in exceptional 

 cases one -half more than this. 



It will be readily understood that the application of water 

 to these winter and summer water-meadows in such large vol- 

 umes has quite a distinct purpose from that of supplying the 

 needed moisture for the transpiration of the grasses. In short, 

 the practice has been found to be a sure way of greatly pro- 

 longing the growing season of each year, and a cheap means of 

 permanently maintaining a high state of fertility of the soil. 



THE DUTY OF WATER IN CRANBERRY CULTURE 



In the irrigation of cranberries, as in the case of rice and 

 water-meadows, the purpose of the treatment is quite distinct 

 from that of ordinary irrigation. It is true that this crop 

 demands a large amount of water, but its normal habitat is such 

 that ordinarily it is abundantly supplied by natural sub-irri- 

 gation. In this case, the water is demanded chiefly to protect 

 the crop against the ravages of insects and injury from frost, 

 and to prevent winter-killing. 



As the surface of the ground-water is seldom more than one 

 to two feet below the surface of the bog, and as the peat and 

 muck above the water are at all times nearly saturated, the 

 amount of water required for cranberry irrigation is but little 

 more than that necessary to submerge the vines, which will 

 rarely be more than .8 to 1.5 acre-feet. But, except for the 

 flooding for winter protection, the demands for water are so 

 peremptory and the time so short which can be allowed for sup- 

 plying it, that but a low duty is possible when this is measured 

 by the rate at which the water must be delivered. 



