934 



exp?:riment station record. 



ments here reported were made for the purpose of determining whether the small 

 fertiUzing effect of the jihosphoric acid of bone meal found by AVagner, Maercker, 

 and others was not due to the fact that their tests were made on soils which were 

 naturally rich in lime or abundantly supplied with it at the time of the experiment. 

 Three series of experiments in pots of 6 kg. content are reported. In the first 

 two series the fertilizing effect of water-soluble phosphoric acid (superphosphate), 

 citric-acid-soluble phosphoric acid (Thomas slag), and bone-meal phosphoric acid 

 was compared, rye being the crop grown in one series, and mustard in the other. 

 In every case the ajiplication of lime reduced the action of the phosphates (j to f ) 

 and even that of the soil phosphoric acid, the yield from unlimed soil receiving no 

 phosphate being higher than from the same soil receiving lime. The yield was 

 nearly a third greater from bone meal applied in the fall than from that applied in 

 the spring (on rye). In the third series of experiments bone meal of various kinds 

 (fine and coarse) was compared with superphosphate and mineral phosphates Avith 

 the following results, the yield with superphosphate without lime being taken as 100: 



Relative elf'ecliveness of jjliospliuric acidfrum difl'ereut .sources, iritJt. and without lime. 



Double superphosphate, containing 35.43 per cent of water-soluble phosphoric acid. . . 



Chinehas guano, containing 12. 56 per cent total phosphoric acid, C.03 per cent citrate- 

 soluble, 3.14 per cent water-soluble, and 7.6.5 per cent of nitrogen 



Lobos guano, containing 33.19 per cent total 'ihosiihoric acid, .5.62 per cent citrate- 

 soluble, 1.66 per cent water-soluble, and 2.29 per cent of nitrogen 



Algerian phosphate, containing 28.29 per cent total and 0.23 per cent citrate-soluble 

 [iliusjihoric acid 



Algerian ]ih(isphate, containing 26.58 per cent total and 0.41 per cent citrate-soluble 

 phi)sphoric acid 



Raw "Indian bone" meal, containing 23.5 percent phosphoricacidand 4.06 per cent 

 nitrogen 



Bone meal with fat and gelatin removed (fi.iely ground), containing 22.84 per cent 

 phosphoric acid, 5.31 per cent nitrogen, and 21. 1 per cent of particles over 0.25 mm. 

 in diameter 



Bone meal with fat and gelatin removed (coarsely ground ), containing 22.72 per cent 

 phosphoric acid, 5.28 per cent nitrogen, and 87.2 per cent of particles over 0.25 mm. 

 in diameter 



Steamed bone meal (fine), containing 25.9 per cent phosphoric acid, 4.23 per cent 

 nitrogen, and 13.4 per cent of particles over 0.25 mm. in diameter 



Steamed bone meal (coarse), containing 26.01 per cent of iihosphoric acid, 4.18 per 

 cent of nitrogen, and 95.5 per cent of particles over 0.25 mm. iu diameter 



The effectiveness of the l)one was very largely dej^endent upon its fineness. 



On the question of th.e relative value of diflferent phosphates, D. Prianish- 

 jsiKov (Landiv. Vers. Stat, 56 {1901), No. 2-3, pp. 107-140, pis. S).—A brief review of 

 previous investigations on the subject is given and sand and soil cultures in 4 to 5 kg. 

 pots with different forms of calcium phosjihate, and different kinds of mineral jihos- 

 phates are reported. A variety of cereals and leguminous plants were grown. The 

 mineral phosphates showing the lowest solubility in 2 per cent citric acid gave the 

 smallest yields. The cereals in general (wheat, rye, millet, etc. ) showed a very lim- 

 ited capacity for assimilating the crude phosphates. Buckwheat, lupines, peas, and 

 mustard utilized them to a greater extent. Bone meal proved a much better source 

 of phosphoric acid than mineral phosphates even in case of millet, which sliowed 

 the lowest assimilative capacity. The freshly jirecipitated tricalcium phosphate was 

 also very assimilable as compared with the mineral phosphates and dicalcium phos- 

 phate gave higher results than the monocalcium (or monopotassium ) phosphate. 

 The order of assimilability was mineral phosphate (phosphorite), bone meal, Thomas 

 siag, freshly precipitated tricalcium phosphate, and dicalcium and monocalcium 

 phosphate, all being assimilated to a greater extent l^y buckwheat, lupines, etc.. 

 than by the cereals. The experiments with mineral phosphates on black soil from 

 southern Russia and onpodzol soil from northern Rassia showed that the phosphates 



