13 



Now the next question of practical importance is this: Does an 

 average crop of these plants require the soil to contain as many 

 pounds of nitrogen as the table indicates? To this science 

 answers no, for the simple reason that the roots and the 

 stalks which remain on the field, and are not included in 

 the dry substance, contain also nitrogen, and because, more- 

 over, it is impossible to assume that the entire supply 

 of nitrogen can ever be taken up by any crop. There- 

 fore, more than the table indicates must be in the ground. 

 Of 100 pounds of nitrate of soda, analyzing on an average from 

 fifteen to sixteen per cent, of nitrogen, probably not more than 

 ten pounds are utilized for the production of a crop. Now 100 

 pounds of nitrate of soda per acre, that is to say, a fertilization 

 of ten pounds of nitrogen per acre, should produce results 

 which are easy to calculate. If sixty pounds of nitrogen are 

 contained in a crop of 2140 pounds of oats, and 3500 of straw, 

 then ten pounds of nitrogen should produce an additional quan- 

 tity of some 350 pounds of oats and some 580 pounds of straw. 



The average content of nitrogen of all plants which are gen- 

 erally being cultivated is known, hence the additional amount 

 which ten pounds of nitrogen should produce in harvest sub- 

 stance, should be as follows: 



Wheat 350 pounds 



Rye 330 



Barley 420 



Oats 350 



Maize (corn) 420 



Rice looo 



Buckwheat 420 



Potatoes 2600 



Beet roots 4500 



Cattle turnips. . . . 3900 



Carrots 3?oo 



Chicory 3400 



Meadow hay 645 



Green maize 5300 



Rape 210 



Poppy 170 



Cotton 270 



Hops 70 



Sugar-cane 2000 



White cabbage . . . 4200 



Cauliflower 1500 



Kohl-rabi 1400 



Cucumbers 6000 



Onions... 3700 



of grain and 500 pounds of straw 

 850 

 600 

 580 

 580 

 1 200 

 640 



tubers 300 

 roots 900 lea -es 



1000 



560 

 410 

 hay 



green plant substance, 

 grain and 600 pounds of straw 

 seed 500 " " 



100 



flowers 320 " leaves and 

 tendrils 

 sugar-cane 

 heads 



" and 1500 rjounds of leaves 

 bulbs 1200 * " 

 cucumbers 

 onions 



