258 SOILS AND PLANT LIFE 



195. How to succeed with Clovers. — The farmer who 

 would succeed in growing these virtuous crops, which 

 maintain the fertility of his lands and at the same time 

 yield nutritious forage for his animals, must see to it 

 that the causes of failure are, in so far as it is within his 

 power to do so, removed. It follows that : 



(1) If the soil is acid, the acidity must be corrected. 



(2) If it is deficient in phosphorus or humus, these 

 must be added to it. 



(3) If the necessary bacteria are absent from the soil, 

 it must be inoculated. 



(4) A suitable nurse crop must be used. 



(5) The seed must be planted at the proper depth in a 

 well-prepared seed bed and uniformly covered. 



Fig. 114. — Applying limestone to the land. 



196. How to correct an Acid Soil. — An acid soil 

 may be corrected bj^ the adchtion of crushed limestone 

 to it. 



This is one of the most abundant rocks found in Nature. 

 It is used not only for making lime, but very commonly 

 for foundations of houses, cellar walls, etc. 



When this rock is used to correct the acidity of the soil, 

 at least half of it should be in the form of fine powder, or 



