The Analysis ov Fkrtiuzers. '281 



lected on their homesteads or gathered in their vicinity. 

 But the demands of liigh farming cannot be met by the 

 return to the soil of the coarse and scant materials left over 

 after the great bulk of concentrated products has been sold 

 aAvay from the farm. The home made manures wlicn care- 

 fully husbanded will go far to delay the exhaustion of the 

 soil ; but for the highest and most profitable results, some 

 adjunct representing the crops and stock carried away must 

 be added. 



The results of the analysis of soils and plants and of 

 experiments regarding plant food point out the fertilizers to 

 be sought and used. Compounds of potassium, phosphorus 

 and nitrogen in the form of potash, phosj^lnjiic acid, and 

 ammonia or nitric acid, have been shown beyond all ques- 

 tion to be the most efficient in the restoration of the fertility 

 of the soil. 



Such being the acknowledged power of these ingrc/'-ents 

 of plant food, it is not a wonder that substances rich in one 

 or more of these are more and more sought after. The 

 increasing demand has brought into requisition materials 

 gathered from many sources. 



Let us for a little look at the source of supply. 



Potassium Compounds. — Wood ashes have until recently 

 been the source of enrichment of tlie soil in potash. The 

 supply however has always been limited; perhaps never 

 more than 30,000 tons have been gathered in all the coun- 

 tries in a single year. But the demands of the arts have 

 drawn away a large portion of this, and only a small part 

 has found its way back to the soil. But the mines of Stass- 

 furt, Saxony, have put a half u million tons of potassium 



