483 



of fertilizer analysis; apparatus for determining nitrogen according to 

 the Kjeldabl method; an oven for drying huge samples of grasses, 

 iorage plants, etc.; and a modification of the Schulze Tiemann appa- 

 ratus for determining nitric acid, devised by T. B. Osborne. 



The station uses an Otto gas engine of one and one quarter horse 

 power for running the mill used for grinding samples of feeding stuffs 

 for analysis, and has found it very satisfactory. 



(-OMPARATIVK AGRICULTURAL VALUE OP SUPERPHOSPHATES AND 

 CERTAIN NATURAL OR RAW PHOSPHATES (pp. 203-219). 



For tho last 3 years the station, with the co-operation of farmers in difforont parts 

 of the State, has cariied out ficM experiinonts designed to give information on 

 this snbjcct. Facts which snggested the cy.pcrimeiUs may hero be again biielly 

 stated. 



The market price of phosidioric acid varies greatly according to tho form in wliich 

 it is bonglit. Thns, it. costs in dissolved boneblaciv abont 8 cents per ponud; in dis- 

 solved Sonth Carolina rock, between f) and G cents ; in IJolivian gniino, between 4 and 

 f) cents; and in Grand Cayman's phosphate and gronnd Sonth Carolina rock, 3 cents 

 a ponnd. 



That the more expensive forms are also the ones most quickly available to i)lants 

 may readily be admitted, Ijut it is a question whether the cost prices stand always in 

 direct relation to the agricultural value ; that is, on land deticient in phosphates will 

 $5 per acre spent in buying dissolved bone-black, for instance, yield a greater or less 

 return in the long run than the same money spent for South Carolina rock or other 

 raw phosphates, seeing that more than twice as much phosphoric acid can be bought 

 for the same money in some of the cheaper forms, as can be bought in dissolved bone- 

 black ? The fact that the farmers of this Statespend annually from $275,000 to|300,0C0 

 for phosphoric acid alone, makes this question practical and important. * * * 



The general plan of these experiments has been to broadcast over the whole lield 

 under experiment a liberal quantity of nitrogenous matter and potash salts, and 

 to divide it then into seven or more plats of equal size. On one plat a quantity of 

 dissolved bone-black was used, which, it was believed, -would not be in excess of 

 the needs of a full crop, but rather slightly deticient. Two other plats, with no 

 phosphates, served to show what the land could produce without tho addition of 

 l)hosi)hates. On single plats each of the other phosphates was used in such quantity 

 that the cost of each was just equal to the cost of the dissolved bone-black on the 

 first plat. The comparative effects were measured by the weights of the crop 

 jiroduced. 



The results of experiments on three different farms are given. Owing 

 to the nuevenness of the land used in one experiment " the results there 

 are of little use." Of the two remaining one was commenced in 1887, 

 the other in 1888. The first was on seven eighth-acre plats. In 

 1887 dissolved bone black 32 pounds, finely pulverized (xiand Cay- 

 nnin's Island phosphate 50 pounds, Tiiomas slag G7.5 pounds, ground 

 South Carolina rock 70 pounds, and gyi)sum 10.9 pouinls, were each 

 applied on one plat, and two plats received no phosphate or gypsum. 

 All of the plats received muriate of potash at the rate of 200 pjunds 

 per acre, and sidphate of ammonia at the rate of 100 pounds per acre. 

 As the object was to observe the after effects of the different i)hos- 

 l)hates, no i)hospliates were applied iu 188S and 1880; but muriate of 

 potash, 320 pounds per acre each year, and sulphate of ammonia, 100 



f 



