100 LIME AS FOOD FOR PLANTS. 



and dry seasons, better than any other soils whatever. Time, and 

 the increase of vegetable matter, will bring those qualities to the 

 same perfection in soils made calcareous by artificial means, as 

 they are in soils made calcareous by nature. 



The subsequent gradual accumulation of vegetable or other 

 putrescent matter in the soil, by the combining or fixing power 

 of calcareous earth, must have yet another beneficial effect on 

 vegetation. The soil is thereby made darker in colour, and it con- 

 sequently is made warmer, by more freely absorbing the rays of 

 the sun. [This must cause earlier ripening of all the vegetable 

 growths.] 



[There is another power or function of lime in soil, indispensa- 

 ble to the perfection, healthy growth, and perhaps even to the ex- 

 istence of every plant ; and which has already been considered as 

 a proof of neutral soils. This is to supply, through the roots, to 

 every growing plant some lime in soluble state which will remain 

 fixed in the plant. This quantity varies with the kind of plant, 

 and its wants in different stages of growth ; and however varying 

 in different kinds of plants, even when most abundant, it is always 

 very small in proportion to the other (organic) matters taken up 

 by and retained in the substance of plants. By reducing the plant 

 to ashes only can the lime taken up by the roots be found, and the 

 proportion to the ashes and to the former vegetable substance be 

 known. 



It may be perhaps deemed a contradiction, or drawing a distinc- 

 tion where there is no real difference, to affirm the absolute necessity 

 of every plant receiving through its roots, a certain proportion of 

 lime, however minute, and yet denying that lime serves as food for 

 plants. I admit the difficulty of clearly discriminating by defini- 

 tion between the two functions. Still, there is great difference 

 between the manner and results of the supply of "lime to plants, 

 and of the aliment which they draw from putrescent manures, 

 humus, or other soluble organic matter. According to the quantity 

 of soluble putrescent manure supplied to or naturally in a soil 

 (unless so enormous as to be hurtful), so will be the quantity of 

 the earliest vegetable growth thereon. But if a soil has been so 

 moderately supplied with lime, as to be barely rendered neutral, 

 the subsequent addition of any greater quantity of lime will add 

 nothing directly, or speedily, to the production of grain or other 

 ordinary crops nor to the quantity of lime taken up by the whole 

 of such succeeding growth. If a soil so destitute of organic mat- 

 J ter such as is recognised by all as furnishing food to plants as 

 to be nearly barren, is supplied properly and profusely with putres- 

 cent manures, the next growth of vegetables may be remarkable 

 for luxuriance and heavy product. But if this rich supply of food 

 had been entirely withheld; and lime or calcareous earth given 



