GREEN MANURING. Ip 



the results show that a direct application of nitrate of soda 

 to the crop to be grown is more effective than an indirect 

 application, using it in the form of a non-legume green- 

 manure. 



This point, it must be remembered, is true when the 

 effectiveness of green-manure as a fertilizer is under study; 

 if the green crop is intended merely to prevent soil wash- 

 ing, as a soil cover, or as a means of preventing loss by 

 leaching of available plant food, non-legumes may, of 

 course, be used. As a matter of practical farm economy, 

 however, legumes should always be grown if possible, so 

 that the supply of fertilizer nitrogen may be increased. 



POTASH PHOSPHATE MANURING. 



In the illustrations so far presented, the reader will 

 notice that in each case the pots have been supplied with 

 potash and phosphoric acid, because no plant can make its 

 growth without these two substances. Furthermore, in 

 order that leguminous plants may accumulate their ferti- 

 lizer nitrogen, it is necessary that potash and phosphoric 

 acid be applied first, or at any rate be present in the soil in 

 available forms and in ample quantities. Many soils con- 

 tain considerable quantities of potash and phosphoric acid, 

 but as they are in such an insoluble state, they cannot be 

 absorbed by the growing crop and are, therefore, of little 

 value. 



