618 SELECTIONS FROM ADDRESSES. 



phosphate of lime is, to produce a phosphate which is soluble 

 in water and can be immediately used by the plant, whereas 

 ground bones alone dissolve so slowly that plants can hardly 

 obtain enough from them each year. Now 40 per cent, of sul- 

 phuric acid will produce the largest quantity of soluble phos- 

 phate, and if this be used on a sandy, gravelly soil, that part 

 not used by the plant will be soon washed through and lost, 

 and this loss is serious ; whereas on a highly absorbent soil, 

 this portion would be retained for future crops. Consequently, 

 according to the retentive power of the soil, 40, 30, or 20 per 

 cent, would be the right quantity. In these light, sandy soils, 

 20 or 25 per cent, would be enough, as thereby the remaining 

 slowly soluble phosphate of lime would be brought into a state 

 of the finest division, and be permanently useful after the sol- 

 uble portion had been taken up by the crop or washed away. 

 In a prize essay on this subject, read before the Royal Agri- 

 cultural Society, in London, Spooner says : " I may, however, 

 observe, that in an experiment during the last season, in which 

 one portion of the land was manured with bones and acid, in 

 different proportions, that which had more bones and less acid, 

 proved a somewhat better crop than that where fewer bones 

 and more acid were used, the expense being the same in both 

 instances." Here all reference to the absorbent qualities of the 

 soil are overlooked, when probably they were the chief ele- 

 ments by which the question was resolved. 



I do not advocate mixing lime, except as before-mentioned, 

 or in particular cases, or leached ashes, or sulphate of iron, in 

 the heaps. Lime and ammonia are antagonists ; they cannot 

 exist together, and lime being the strongest, always drives am- 

 monia away. It is true that the contact of the atmosphere and of 

 rain converts lime into carbonate of lime, a much less injurious 

 substance, but this is a tedious operation. The benefit which 

 sometimes arises from liming is, that it lightens the soil, and 

 the lime and lime water coming into contact with old lumps 

 of concentrated manure, or with the ammonia left in the soil, 

 sets it free for the use of the crops, but too often liming pro- 

 duces barrenness afterwards, by driving nearly all the ammonia 

 put of the soil, and herein consists the danger of using it. Dr. 



