EXPERIMENT STATION BULLETINS 291 



adapted to £jrass lands and lawiis, and is free from the bad odor often given off by 

 mixed fertilizers. jNIoist meadows are benefited by a dressing of bone meaL If the 

 bones that now adorn the back yard and pasture lot should be ground into a powder 

 and scattered on a crop-worn field, the results would surprise some farmers. 



4. Potash Manure. The best and cheapest is that neglected home product — 

 wood ashes. These contain an average of 5 per cent of potash, besides a sensible 

 amount of phosphate, and a very large amount of carbonates of lime and magnesia; 

 they are an all-round plant manure so far as mineral matter is concerned, supply- 

 ing each ash element. "■ 



Unless the farmer can bring into active form the great store" of potash in his soil, 

 he will then have to buy the German potash salts, the muriate or sulphate. These 

 salts are yearly coming into greater prominence as potash fertilizers, but their sale 

 in Michigan in separate form has not been large. 



The influence of potash on plant life is masterful; no plant can grow without it, 

 and its influence in developing the carbohydrates, and maturing fruits, is marked 

 and apparently controlling. 



5. yitrcgen Compounds. Nitrogen is the bottled wine of the vegetable feast. If 

 the term stimulant can be applied to any organization destitute of a nervous system, 

 then nitrogen is the stimulant of plant life. In any of its combined forms it gives 

 depth of color and exuberance of growth to vegetable life, and when in abundant supply 

 it causes the plant to break forth into riotous growth. The great reservoir of nitrogen 

 is the air, but the leaves of plants though constantly bathed in nitrogen, cannot 

 drink in a particle. It is only nitrogen in conihination that can be appropriated by 

 the plant, and this enters the plant by the roots and comes from the soil. A small 

 amount is brought to the soil by the rain, washing out the ammonia and nitrates of 

 the air, but the amount is not large and entirely inadequate to supply a crop. 



A large amount of active nitrogen in the form of nitrates is yearly formed in 

 every w^ell cultivated field, and this is the cheapest way of securing a supply of this 

 costliest element of plant growth. The raising of leguminous crops, like the clovers, 

 is the next cheapest way of securing a supply. 



Combined nitrogen is purchased in three forms: salts of ammonia, nitrate of soda 

 and organic nitrogen in the form of dried blood, fish scraps, cotton seed meal, etc. 



6. Tankage, is a complex and variable material obtained from the waste resi- 

 dues at the slaughter houses, the garbage collected by the scavengers in cities, etc. 

 These materials are dried, the grease extracted in tanks and this tankage by itself, 

 or mixed with phosphates, potash, etc., is sold as a fertilizer. It is mainly used to 

 give bulk to the concentrated fertilizers made from bone and rock phosphate. 



SCHEDULE OF COMMERCIAL PRICES. 



The following prices per pound for fertilizing materials may be used in estimat- 

 ing the commercial value: 



Per pound. 



Nitrogen in nitrates $0 13 



Nitrogen in ammonia salts 14 



Organic nitrogen in meat, blood, etc 14 



Cirganic nitrogen in fine bone and tankage 13^^ 



Organic nitrogen in medium bone and tankage 10 



Organic nitrogen in coarse bone and tankage 8 



Phosphoric acid, available 4^:5 



Phosphoric acid, insoluble, in fine bone and tankage 4 



Phosphoric acid, insoluble, medium bone and tankage 'SVj 



Potash as muriate ■^Vi 



Potash as sulphate and in wood ashes 5 



COMMERCIAL VALUE AND AGRICULTURAL VALUE. 



The commercial value and the agricultural value are not identical. The commercial 

 value merely represents the cost of the material to make the fertilizer, if any one 

 should attempt to make his own. The agricultural value or the benefit from the use 

 of such fertilizer will depend upon a variety of conditions, such as the kind of soil, 

 the crop, the season, the tillage, time of application, etc., etc. Let no one suppose that 

 the estimate of the commercial value is a guarantee of a corresponding profit by its 



