128 THE PRACTICAL SIDE OF 



basic slag are so much more useful on sour 

 than on sweet soils. Lime has also the 

 faculty of converting certain insoluble phos- 

 phates, especially those present in clay soils, 

 into phosphate of lime, which is more easily 

 utilised by plant life, while it assists in 

 rendering potash soluble for the same pur- 

 pose. Thus, lime not only provides plants 

 with food, but it is an important agent 

 in providing crops with the latent nitrogen, 

 potash, and phosphoric acid which most 

 soils contain. 



We have seen that dung or farm-yard manure 

 possesses two important properties — in a 

 word, that it not only provides food for plants, 

 but that its mechanical action in the improve- 

 ment of the soil enables plants to grow with 

 greater freedom, and to appropriate more 

 easily the food which it supplies. It is 

 important, however, to discriminate between 

 the dung produced by each class of stock, 

 and the quality of that dung as it is influenced 

 by the food which the stock consume. Fresh 

 dung produced by cows, when mixed with 

 straw, contains less nitrogen, phosphoric 

 acid, and potash than fresh dung produced 

 either by the horse, the sheep, or the pig. 

 The manure produced by sheep contains much 



