OF THE PRECEDING CHAPTERS. 181 



gen, and decomposes easily. For this reason, it should 

 be at once covered, or made into compost. 



Saline and mineral manures. 



Lime. Used as quicklime, slaked lime, and mild, 

 or air-slaked lime. 



Quicklime only to be used where there are no rich 

 manures, as when in contact with them, it liberates 

 nitrogen, and thus deteriorates the manure. 



The effect of lime in the soil, is to decompose or- 

 ganic and inorganic compounds, as well as to furnish 

 food for plants. 



Marls, a form of carbonate of lime; shell sand also 

 another form : their beneficial effect as manures. 



CHAPTER X. 



Saline and mineral manures [continued). 



Gypsum, or plaster of paris, a compound of sulphuric 

 acid and lime, valuable food for plants. Its good effects 

 in attracting gases and moisture; abuse of it by adding, 

 for a series of years, without other manure. 



Common salt, nitrate of soda, nitrate of potash 

 (saltpetre), carbonate of soda, etc., all powerful ma 

 nures. 



None of these, nor guano, should be in immediate 

 contact with the seed, and are best applied in small 

 quantities, with half the usual allowance of farmyard 

 manure. A mixture of them, much better than one 

 alone. 



Wood ashes, coal ashes, peat ashes, are all good 

 manures ; ought to be kept from rain till they are 

 used. Good to extirpate weeds, and to mix with 

 other things for sowing. 



Soot, a rich manure, contains much ammonia and 

 inorganic substances. 



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