POTASH-PHOSPHATE MANURING. 21 



The need of potash and phosphoric acid is well 

 illustrated in another of Prof. Wagner's experiments. The 

 pots shown in the upper half of illustration Figure 7 

 were planted to peas, and are divided into three sets of two 

 pots each. They were treated as follows: First two, no 

 fertilizers ; second two, potash and phosphoric acid ; third 

 two, potash, phosphoric acid and nitrogen The three sets 

 are marked by "O" no fertilizer, "KP" potash and 

 phosphoric acid, and " KPN" potash, phosphoric acid and 

 nitrogen. The growth shows that potash-phosphate ma- 

 nuring was practically as effective as when nitrogen was 

 added, and that the use of nitrogen fertilizers in this case 

 was a needless expense. 



The lower half of this illustration shows pots treated 

 exactly the same way, but planted to oats, a non-legume 

 As the picture shows, the potash- phosphate pots are 

 scarcely better than those not manured ; but the pots 

 treated with nitrogen, in addition to potash and phosphoric 

 acid, made an excellent growth. In other words, the peas 

 secured practically all the nitrogen they needed, but the 

 oats have not this power, and unless they are given the fer 

 tilizer nitrogen, they will fail to make profitable growth 

 It is scarcely necessary to remark that the results would 

 have been similar had the legumes, instead of peas, been 

 any of che clovers, vetches, lupines, soja beans, etc. 



From the data already given, Prof. Wagner established 

 two important conclusions : 



T. Sufficient potash and phosphoric acid must be sup- 



