SOIL IMPROVEMENT 



119 



Calcium. Calcium is an essential plant food of which there is 

 generally enough in the soil for plant needs. Applications of it, 

 however, in the form of lime, are usually beneficial. One of the 

 most useful effects of lime is in correcting acidity of soils. From 

 various causes, there sometimes form in soils acid compounds, which 



A LIME-SPREADING MACHINE AT WORK 



are injurious to plant growth. Such soils will not produce good 

 crops. It is necessary to ' sweeten ' them, as farmers say. This is 

 done by applying lime, which combines with the acids and destroys 

 the injurious compounds. Lime improves soil texture, sets free 

 much unavailable plant food, and prevents many fungous diseases. 

 The effect of lime is largely a forcing one. Therefore it should be 

 used as a supplement to other plant foods, not as a substitute for 

 them. A wise old proverb says, 



" Lime and marl without manure 

 Will make both farm and farmer Door." 



