MANUKES. 33 



onr cultivated plants. It is indispensable to such plants 

 as beets, potatoes, peas, beans, fruit trees, and vines, but 

 to Kalmias and coniferous trees it is injurious. It is 

 of special value when combined with phosphoric acid, as 

 in bone earths, or with the sulphuric, as in gypsum. Linie 

 in the soil enables it better to absorb and retain heat. 

 It is of great value as an application to cold, tenacious 

 soil-s, rendering them of more open texture, and making 

 the organic matters therein available to plants. It, on the 

 other hand, makes light soils more adhesive, acting as an 

 amendment. It decomposes organic matters, whether 

 vegetable or animal, and forms with them a partially solu- 

 ble compound peculiarly fitted for the food of plants. 

 But as it has the property of setting free ammonia, it 

 should never be applied in connection with fresh animal 

 manures. Mixed with stable manure or guano, it would 

 speedily free them from nearly all their ammonia, that indis- 

 pensable and most costly constituent of the food of plants. 



This will not happen to any great extent, and there will 

 be little loss, if the mixture takes place in, and both the 

 lime and manure are entirely covered with the soil, which 

 will at once absorb whatever ammonia the lime sets free. 



The great value of lime, aside from the small quantity 

 directly available to plants, is in hastening, as above stat- 

 ed, the decomposition of decaying matters in the soil, and 

 rendering them assimilable by plants. The old black' 

 mould of kitchen gardens and other soils rich in humus, 

 it will suddenly render wonderfully productive, and they 

 will consequently speedily become exhausted, unless new 

 supplies of organic manures are added. Lime alone, ad- 

 ded to a soil, will speedily exhaust it if the crops are re- 

 moved and no return of manure is made. 



Potash is another alkaline substance indispensable to 

 healthy vegetation. It occurs in all plants, and this, and 

 lime and soda, are regarded by Liebig as specially destined 

 to serve as bases for the organic acids of vegetation, 



o* 



