80 AGRICULTURE 



turnips, swedes, cabbages, red clover, oats, 

 and others. Crops are better nourished on 

 land from which the surplus water has been 

 withdrawn, not only because manures de- 

 compose and humus nitrifies more quickly, 

 but also because supplies of food are brought 

 forward to the roots more steadily and con- 

 tinuously. On land saturated with water 

 plants can only utilize the plant food in the 

 immediate neighbourhood of their roots, 

 and when this is appropriated they necessarily 

 suffer from lack of nourishment. But when 

 drains are put into land water is steadily 

 and continuously attracted towards them, 

 that is to say, there is a constant movement 

 of the water throughout the soil in the 

 direction of the means of escape now pro- 

 vided. Water, therefore, is no longer 

 stationary, but in motion, so that fresh sup- 

 plies of soluble food are constantly being 

 brought within range of the feeding roots, 

 with consequent advantage to the crop. 



One great advantage of drainage in the 

 case of tillage land is that the land can be 

 more easily and more thoroughly cleaned, in 

 fact it is the difficulty of getting rid of weeds 

 that ofteu puts wet land out of cultivation 

 altogether. If tillage operations and the 

 cleaning of land are rendered easier by 



