LONG-CONTINUED ACTION OF BONES. 57 



by grass land for thirty years, and the effects of a first applica- 

 tion of lime are often visible for an equal period. An experi- 

 ment made by Mr Russell at Kilwhiss in Fife, enables me 

 to illustrate the way in which such applications long ago made, 

 and perhaps forgotten, may seriously interfere with and modify 

 the results of field experiments. 



Of two fields, apparently identical in quality, and adjoining 

 each other, and on which the experiments were made, the one 

 had been boned with twenty bushels of bones thirteen years 

 previous to 1841. In 1842, both fields were manured at the 

 .rate of ten loads per acre of farm-yard manure of good quality, 

 and sown with turnips. On the old-boned field, the crop was 

 four times as bulky as on the unboned field. In 1843, a crop of 

 barley was taken from each after the turnips, and the crop on 

 the two parts averaged, per imperial acre 



bush. Ib. Weight per bush. Sold for 



On the old-boned land, 36 14 57 Ib. 28s. 



On the unboned, . 31 19 56 Ib. 27s. 



Difference, . 4 51 1 Ib. Is. 



So that, after fifteen years, this old-boning caused a large in- 

 crease both in the turnip and in the corn crops. And had com- 

 parative scientific experiments been made upon the two fields, 

 there is every reason to believe that results, by no means due to 

 the substances applied, would have been obtained from that to 

 which the bones had been so long before given. 



Such invisible differences no doubt often exist among culti- 

 vated soils, differences so minute, that even chemical analysis 

 cannot discover them, though their effects may be visible upon 

 the crops.* To a new tenant, the historical treatment to which 



* Suppose a bushel of bones to weigh 50 Ib., then a dressing of 20 bushels 

 adds 1000 Ib. of bones to the acre. To a soil six inches deep, this is in the 

 proportion of 0.06, or ^ of a per-cent, less than an ounce to 100 Ib. of 

 soil. But of this bone only one -half (0.03 per cent) is mineral matter, 

 which can be detected, and which is likely to remain for a length of time in 

 soils of ordinary lightness. This proportion is very minute and difficult to de- 

 tect, suppose it all to be in the soil ; but how much more difficult must it be to 

 determine the amount of this bone which remains in the soil after the lapse of 

 fifteen years, when so much of it has been taken out by the crops, has sunk into 

 the subsoil, or been washed out by the rains. 



