24 THE CONNECTICUT AGRICULTUKAL 



phoric acid is too insoluble to be rapidly available as plant food. 

 This is true of South Carolina rock phosphate, of Navassa phos- 

 phate, and especially of Canada apatite. The phosphate of coarse 

 raw bones is at first nearly insoluble in this sense, because of the 

 animal matter of the bone which envelopes it, but when the latter 

 decays in the soil, the phosphate remains in essentially the 

 '' reverted " form. 



Potash signifies the substance known in chemistry as potassium 

 oxide, which is the valuable fertilizing ingredient of " potashes " 

 and " potash salts." It is most costly in the form of sulphate, 

 and cheapest in the shape of muriate or chloride. 



The valnation of a fertilizer signifies estimating its worth in 

 money, or its trade value ; a value which, it should be remem- 

 bered, is not necessarily proportional to its fertilizing effects in 

 any special case. 



Plaster, lime, stable manure, and nearly all the less expensive 

 fertilizers have variable prices, which bear no close relation to 

 their chemical composition ; but guanos, superphosphates and 

 other fertilizers, for which $30 to |80 per ton are paid, depend 

 chiefly for their trade value on the three substances, nitrogen^ 

 phosphoric acid and potash, which are com])aratively costly and 

 steady in price. The money value per pound of these ingredients 

 is easily estimated from the market prices of the standard articles 

 which furnish them to commerce. 



The a^oerage trade values, or cost in market per poimd, of the 

 ordinarily occurring forms of nitrogen, phosphoi'ic acid and 

 potash, as found in the Connecticut and New York markets, and 

 employed by the Station during the last three years, have been as 

 follows : 



Trade- Values for 1881, 1882 and 1883. 



1881. 1883. 1883. 

 ^Cents per pound.^ 



Nitrogen in nitrates, .- 26 26 20 



" in ammonia salts, -. 22^ 29 26 



" in Peruvian Guano, fine steamed bone, dried and fine 



ground blood, meat and fish, superphosphates , 



and special manures. , 20 24 2H 



'' in coarse or moist blood, meat or tankage, in cotton 



seed, linseed and Castor Pomace, 16 18 18 



" m fine ground bone, horn and wool dust. 15 17 17 



" in fine medium bone, 14 15 15 



" , in medium bone, 13 14 14 



" in coarse medium bone, 12 13 13 



" in coarse bone, horn shavings, hair and fish scrap, . . 11 11 11 



