15 



the ground. At all events the foremost agricultural chemist of 

 Germany has not hesitated to affirm, that the whole question of 

 the artificial fertilization of the soil turns round the one ques- 

 tion: wherein consists the most rational economy with nitrogen. 



And he says on that subject: u Schultz-L,upitz sees in the 

 cheapest and most abundant securing of nitrogen, in the hus- 

 banding of the same, in its highest possible utilization, the 

 real true task and the main object of fertilization. Is this 

 standpoint one-sided? No." And this most emphatic de- 

 claration he bases first upon the fact that the leguminous 

 plants possess the ability to draw upon the inexhaustible supply 

 of nitrogen offered by nature in the atmosphere and upon the 

 further fact, that the nitrogen-gatherers can be made nitrogen- 

 hungry, that is to say, can be induced to draw much more freely 

 upon the inexpensive supply open to them than they do under 

 ordinary circumstances. 



On average soils Prof. Wagner calculates the requirements of 

 nitrogen per acre to be for the several crops as follows: 



Tor cereal crops from 13-50 Ibs. of N. 100-400 Ibs. of nitrate of soda. 

 " potatoes " 22-45 " " 150-300 " 



" sugar beets " 22-50 " " 150-380 

 *' tobacco " 13-26 " " 100-200 " " 



In case of potatoes and sugar beets only nitrate of soda should 

 be applied, because sulphate of ammonia does not prove advan- 

 tageous. If it is possible at all to talk about controlling the 

 vegetation of plants, that control is exercised by nitrogen. 

 Whereas it is wise policy to mete out phosphoric acid and potash 

 in abundance to all crops, it is unwise to give more nitrogen 

 than is required for the production of a maximum crop. The 

 excess of phosphoric acid and potash is not lost, not consumed, 

 but stays in the ground, an excess of nitrogen, the most expen- 

 sive element, would be consumed. 



THE NECESSITY OF PHOSPHORIC ACID. 



Nearly all kinds of soil contain phosphoric acid, but mostly 

 in a form in which it is not easily taken up by the plants. Even 

 in soils that are very rich in phosphoric acid, the quantity which 

 becomes each day available for the roots of the plants is small, 



