11 



While 0.3 gram of phosphoric acid, iu superphosphate, could have 

 yielded the plant 0.1 grain of phosphoric acid, the niixlure of 0.3 

 gram iu superphosphate and 0.3 gram in boue-meal yielded in one 

 case, 0.12 gram, in another case, O,0H8 gram of phosphoric acid. 

 The barley, therefore, took up of the bone-meal phosphoric acid 

 only the small average quantity of 0.01 gram, that is, practically 

 nothing. 



b. The experiments with larger amounts of bone-meal phosphoric 

 acid yielded the same result. 0.3 gram in superphosphate and 0.9 

 gram of bone-meal phosphoric acid gave an average yield increase 

 of 104. G7, while the 0.3 gram in superphosphate, alone, increased 

 the yield 83.65. The increase due, therefore, to the O.'J gram of 

 bone-meal phosphoric acid was 21.02 grams. 



1.5 grams of bone meal phosphoric acid, with 0.3 gram in super- 

 phosphate but slightly raised the increase, that is to only 105.91 

 grams, so that for these l.o grams of bone-meal phosphoric acid 

 only 22. 2G grams of increase was due to the bone-meal phosphoric 

 acid, against the 120.79 grams produced by an equal application of 

 phosphoric acid in superphosphate. With application of 0.9 gram 

 and 1.5 grams of bone-meal acid, 0.049 gram and 0.052 gram, 

 respectively, were taken up. The same quantities of acid in super- 

 phosphate yielded the plants 0.286 and 0.317 gram respectively. 



c. Precisely the same result was obtained when stronger applica- 

 tions were made of super|)hos|)hate as chief fertilizer. 



While 0.6 gram of superphosphate acid with 0.6 gram of boue-meal 

 acid gave a yield increase of 152.74 grams, 0.6 gram of superphos- 

 phate acid, alone, would have given an increase of 167.29 grams. Of 

 the phosphoric acid in the bone-meal in this case, only 0.038 gram 

 went into the plant, while of 0.6 gram of superphosphate acid 0.2 

 gram was taken up. When 0.6 gram in superphosphate and 1.2 

 grams of bone-meal acid were given, an increase of yield of 156.05 

 grams were obtained, so that here, also, the bone-meal phosphoric 

 acid had produced no effect. Only 0.058 gram from the latter was 

 taken up, while from 1.2 grams of superphosphate acid 0.371 gram 

 was taken up. Finally, when 0.9 gram of superphosphate and 0.9 

 gram of bone-meal phosphoric acid were applied, tliere was an 

 increased yield of 181.94 grams, whereas 0.9 gram of superphos- 

 phate acid would have given an increase of 187.87 grams. Here 

 again the bone-meal phosphoric acid was quite ineffective. Of the 

 bone-meal phosphoric acid applied, only 0.016 gram was taken up. 



These figures show that with an application of mixed fertilizers 

 containing superphosphate and bone-meal phosphoric acid, one may 

 expect simply the yield increase due to the superphosphate, or, at 

 most, only slightly more than that. Under these circumstances bone- 

 meals do not appear to be profitable phosphoric aeid fertilizers. 



This disposes of the idea that an addition of phosphoric acid, in 

 the form of bone meal, to a supply of available and effective phos- 

 phoric acid, works better than bone-meal phosphoric acid alone. 



