^ ON MANURES. 85 



known by farmers as 'burning soils;' and, by its injudicioije 

 use or repetition, without the aid of animal or vegetable 

 manure to supply the nourishment of which they have been 

 deprived by crops, the growth of which has been thus forced, 

 land, though of superior quality, may at length become ex- 

 hausted. Thus experience teaclies that lime, when applied 

 to land, has different effects upon some soils than it has upon 

 others : on many there is a rapid and permanent improvement, 

 on others there is less benefit, and on some it is said rather to 

 retard than to promote vegetation. This is, no doubt, chiefly 

 influenced by various unascertained properties in the soil, and 

 partly also by differences in the qualities of the lime itself, 

 arising from its mixture with other earths. 



Whether it possesses any further properties, through the 

 stimulating effects of light and heat upon the vegetable fibre, 

 has been conjectured, but has not been supported by any 

 positive fact, and seems to be contradicted by the slow effect 

 of effete lime in its operation upon the soil. It is, however, 

 worthy of remark, that calcareous earth is found in the ashes 

 of all vegetables ; that it is present in a larger proportion in 

 wheat, clover, and some other plants whose growth is espe- 

 cially promoted by the use of calcareous manures, and many 

 are said not to ripen in ground in which it is entirely wanting. 

 We may therefore conclude that it is of the highest importance 

 in the process of vegetation, and that an accurate investigation 

 of its mode of action, by enabling us to judge with more cer- 

 tainty of its powers, would greatly tend to the improvement 

 of agriculture. It is indeed much to be regretted that the 

 subject has not been more fully investigated, and that some 

 more definite judgment has not been framed regarding tJie 

 properties of lime, the effects of which in its application to the 

 soil are exposed to the most contradictory results. Much 

 money has thus been uselessly expended and labour thrown 

 away, which, under better information, might have been 

 saved ; and without scientific analysis of the component parts 

 both of soils and of lime, we remain much in the dark regard- 

 ing their effects on vegetation; but judging from the faint 

 lights with which we have been furnished, we shall still en- 

 deavour, by comparing science with practice, to obtain such 

 instruction as may guide us to an economical and useful appli- 

 cation of this manure to field culture. 



Application of Lime. — Those purposes appear to be — first, 

 to render whatever substances may be lodged in the soil, or 



