418 On a New Mode of preparing Bones for Manure. 



much out of heart. Bones act upon it very strongly ; for the 

 trial-lots are part of 70 acres of turnips and swedes, a good crop 

 produced by superphosphate, notwithstanding the drought ; but 

 wherever that preparation was purposely missed, the yield was not 

 more than four, or at most five, tons to the acre. 



The trial was made on the supposition that certain quantities of 

 each manure were likely to yield equal produce ; and it was pro- 

 posed to test the difference^ not of produce from the same cost of 

 manure, but of cost for nearly the same amount of produce. 

 The mixture was made in this case by throwing together a 

 waggon-load of crushed bones wetted, and, by a mistake of the 

 workmen, half that quantity only of sand. The heap, however, 

 heated violently, and was in a few days fit for use. Three 

 bushels of the mixture are valued higher than two bushels of 

 bones, because the heap sank during the process one foot in 

 four, showing, as I had suspected, that, from the shrinking of the 

 bones, there would be more than two bushels of bones in three 

 of the mixture. 



First Experiment. 



Cost of Manure Produce 

 Bushels of Manure per Acre. per Acre. per Acre. 



£ s, d. Tons. cwts. 



1. 17 bones . . .2 6 9 13 5 



2. 4i sulphated bones . . 1 2 9 14 5 



3. 81 heated bones and sand .10 9 13 5 



The amount of produce was nearly equal, as I had hoped it 



might be, and both preparations show a large saving as against 



unprepared bones. In another experiment a larger quantity of 



each manure was applied with the following result : — 



Cost of Manure Produce 

 Bushels of Manure per Acre. per Acre. per Acre. 



£, s. d. Tons. cwts. 



4. 251 bones . . . 3 10 0 14 5 



5. 11 sulphated bones . .2 3 0 14 5 



6. 12|- heated bones and sand . 1 11 0 17 1 



On the three last lots it will be seen the manures were applied, 

 each at the rate of about half as much again as on the first three 

 lots. The reason was this. I proved in a former Journal, by a 

 careful experiment devised for the purpose, that some manures, 

 when applied in increased quantity, do not produce a corre- 

 sponding increase of crop — have in fact a limit beyond which it is 

 vain to apply them. This view, having since been confirmed by 

 the experience of others, may now be regarded as founded in the 

 laws of vegetation. It is also strikingly confirmed here, for, by 

 increasing the dose of sulphated bones rather more than one half, 

 we get no increase of turnips : and by increasing the rough bones 

 one half, while swelling the expense from 465. to 70^., we get no 



