266 SUPERPHOSPHATE OF LIME. 



In this case the superphosphate and soda, or house ashes, 

 are to be mixed before guano is added. 



Either of the above mixed with twice its bulk of soil may 

 be used as a top dressing for grass, and it is to be sown or 

 scattered during early warm spring rains, at the rate of 

 from 100 to 300 lbs. per acre. At this rate they may be 

 used for top dressing wheat or rye, or sown with oats and 

 grass seed. For roots, it is best to add these compounds to 

 the soil, before sowing, working well in, and then sowing 

 with a seed planter. For cabbages, &c., use 1 lb. to five 

 plants when set out. 



309. Nitrogen, whose conversion mto ammonia has been 

 explained (187), seems to be the great element introducing 

 chemical change, and inducing chemical motion in the ele- 

 ments of soil. Nitrogen, as has been stated (206), always 

 produces for a like weight, like effects, whatever may be the 

 form in which it is introduced into the soil, or compost heap. 

 Nitrogen is the element, which the crude superphosphate 

 lacks, to make it a perfectly efficient artificial manure, when 

 added either alone to soil, already rich in geine, or to peat 

 or swamp muck, after these have been treated with ashes, 

 soda, salt and lime, &;c., as has been before explained. 



There is a source of nitrogen of which the farmer may 

 avail himself, which may be added to his superphosphate, 

 and go far towards furnishing anew to burned bones the ele- 

 ment of which fire has deprived them, or that element which 

 is sought in guano. This source of nitrogen is found in salt- 

 petre, either East Indian, nitrate of potash, or South Ameri- 

 can, nitrate of soda. 



When it is considered that these nitrates alone, are among 

 the most powerful and beneficial of all salts applied by 

 farmers (168), and that, in the opinion of wise and careful 

 English agriculturists, nitrates mixed with common salt may 



