86 AGRICULTURE 



other animals, such as mice and voles, but 

 it cannot be said that suitable conditions for 

 use of this kind often present themselves. 



All water is not alike suitable for irrigation. 

 Water to be serviceable must be free from 

 acids, such as humic acid, nor must it contain 

 plant poisons, like low oxides of iron. Some 

 water also is unsuitable on account of its 

 containing too much lime, which may some- 

 times be seen encrusting plants, and other 

 objects, that it encounters. Speaking 

 generally, however, water from limestone 

 rocks, notably Chalk, is largely used for 

 purposes of irrigation. One can gain some 

 idea of the quality of the water by studying 

 the plants in the brook, or other watercourse, 

 from which it is proposed to draw supplies. 

 If these plants are to a large extent of the 

 type represented by Watercress, Speedwell, 

 Crowfoot, Floating Poa, etc., the water may 

 be assumed to be suitable. If, on the other 

 hand, the plants growing in the brook consist 

 of Sedges, Rushes, Reeds, and similar plants, 

 the probability is that the water is bad. 



The district of England that shows the 

 widest use of irrigation is the south and 

 south-west, where such streams as the Test, 

 Itcliin, Avon, Wiley, and Kennet, are largely 

 utilized for irrigating meadows along their 



