No. 6. DEPARTMENT OF AGRICULTURE. 845 



There is no particular classification of most phosphates, particu- 

 larly the dissolved goods, with reference to mechanical condition, 

 but with raw bones all fertilizer controls adopt a standard of fineness 

 and base the valuation accordingly. The following are the stand- 

 ards and values in common use at this time: 



In the early days of the use of bones as fertilizers they were ap- 

 plied in a very coarse condition, but as their use grew they were 

 made finer and finer, until, in some cases, they were reduced to an 

 impalpable powder. To reduce the bone to powder is too expensive, 

 but now, in most cases, they are ground quite fine. Considerable 

 study of the question of the rapidity of the availability of bones 

 and phosphates has been made in Great Britain in connection with 

 the tenant system of that country, so that due credit could be given 

 for the amount remaining in the soil a given period after applica- 

 tion with the various systems of farming. The degree of fineness 

 of bones was an important factor in this valuation. 



THE LIMING OF LAND AND ITS EFFECT UPON THE AVAILABILITY OF 



PHOSPHATES. 



There has been considerable said from time to time upon this 

 point, and there seems to be considerable difference of opinion ex- 

 pressed. No doubt there are some soils and circumstances which 

 will produce directly opposite results when the land is limed either 

 directly before or after the application of phosphates. The opinions 

 expressed as a result of the first experiment conducted by the French 

 chemists upon this point were to the eliect that lime and phosphates 

 were incompatible, as the soil water had a greater dissolving ac- 

 tion on carbonate of lime than on phosphates, so prevented the 

 crops using the ijhosphate. Be this as it may, there seems to be 

 but little evidence that such is the result in practice, as in very 

 many cases increased yields follow such combinations. This opinion 

 seemed to be substantiated to the greatest extent on the soils 

 already rich in carbonate of lime. On soils that are deficient in 

 lime there seems, on the contrary, to be a benefit from the use of 

 lime and phosphates in eonjunction. While it is doubtful if these 

 should be applied either at the same time or very close together, 



