SOURCES OF NITROGEN OF PLANTS. 93 



Mr. Fritz: Does any one know of a good grass for sandy land? 

 ■Prof. Beal: Ked clover. 



SOURCES OF NITROGEN OF PLANTS. 



BY TKOF. R. C. KEDZIE. 

 [Read at Rochester and East gaginaw Farmers' Institutes.] 



Oat of the sixty-five or more simple or elementary substances known to the 

 -chomist only thirteen are found in tlie crops grown on the farm. Tliey have 

 Leon called the chemicals of agriculture. Out of this bakers' dozen of ele- 

 nieutiiry bodies, all the plants grown on the farm are formed. They do not 

 all appear to be of equal import nee in plant life; some appear to confer a 

 high quality and great nutritive value to the plant, while others appear to pos- 

 sess little distinctive character. Some seem to be present in so large quantity 

 in all ordinary soils that every plant finds enough for its wants. On the other 

 hand a few are in such nioderate amount in many soils and the available stock 

 is so soon diminished that plants find difficulty in obtaining the supply required 

 for producing large crops 



Three substances in these chemicals of agriculture stand out in bold relief, 

 imparting high quality to crops, augmenting their product, yet soonest exhaust- 

 ed in the process of cropping. Tiieso are potas ium, phosphorus, and nitrogen. 

 Wherever a field has been exhausted by cropping, the exhaustion consists in the 

 absence in available form of one or more of these three substances. The dead 

 cotton fields of the South and the tobacco lands of Virginia have been killed by 

 the continuous removal of these three chemicals by changeless cropping. 

 These dead fields shall find a resurrection when these elements are again 

 restored, or when the slow but healing hand of nature shall bring into active 

 form these elements of fertility now locked in insoluble combinations. 



Biit we need not go South to find sick and dying fields. Wherever you find a 

 farm that is run down and out of condition by continuous cropping, always 

 taking off and never restoring the materials for plant growth, you may safely 

 isay that the farm is deficient in available sup[)ly of these three substances. 

 Tliese three are preeminently the chemicals of agriculture, and in determining 

 the value of commercial nianures these are the only substances taken into 

 account. The last legislature passed a law regulating the sale of commercial 

 fertilizers, and this law req'iires an exaot statement of the quality of each of 

 these three substances in fertilizers offered for sale in this State. These three 

 substances have a commercial value as fertilizers as well recognized in the mar- 

 ket as the price of wheat and pork. When it is said that nitrogen in the form 

 of ammonia and nitrates is worth eighteen cents, phosphorus in form of solu- 

 ble phosphates is wo th twelve cents, and soluble potash is worth five cents a 

 pound, it is affirmed that under suitable conditions the farmer can afford to pay 

 such prices for these articles to use as fertilizers on his farm, because the 

 increase of the crop will joay for the outlay and still afford a net profit to the 

 farmer. 



In this passing allusion to commercial fertilizers it is not my design to start 

 a boom for guanos and super-phosphates, but rather to show the subordinate 



