i6 



GREEN MANURING. 



The difference in growth shows the effect of the nitrogen 

 added to the potash and phosphoric acid. The four pots to 

 the right (also planted to oats) received potash and phos- 

 phoric acid in the same manner, and all four were green- 

 manured, the first two by a crop of mustard, the second two 

 by a crop of vetches. These green-manure crops were 

 grown in the pots the previous season and worked into the 

 soil. 



4.- 



U4- 



FIG. 4. 



DIFFERENT RESULTS FROM LEGUME AND NON-LEGUME 

 GREEN MANURE. 



As will be seen from the picture, the effect of mustard 

 and vetches, when used as green-manure crops, is strikingly 

 different. Green manuring with mustard (a non-legume) 

 failed to supply the nitrogen needed, and a very poor crop 

 of oats resulted practically no better than where neither 

 nitrogen nor green manuring was used; while vetches 

 (legumes), being nitrogen gatherers, supplied the nitrogen 

 needed to make a good crop of t oats, and proved equal to 

 the nitrate of soda in the first case. 



