t 517 ] 



nium. nitrate also occurs in air and in rain water. Saltpetre 

 and Chili saltpetre or sodium nitrate are largely used fcr 

 manure. Of ammonium salts, the substance largely used for 

 manure is ammonium sulphate which is manufactured out of 

 gas-liquor, and is therefore a bye-product of gas-works. 

 The crude gas-liquor diluted with water is also used for 

 application on wheat and other cereal crops. Urea is also 

 made use of directly by the roots of plants, and fermentation 

 of urine which results in the generation of volatile ammonia 

 salts, should therefore be prevented, either by applying urine 

 fresh on lands, diluted with water, or storing it in tanks by 

 the addition of an antiseptic substance such as Ferrous 

 sulphate for future use but in an unfermented state. 



825. Nitrates. In connection with the question of re- 

 cuperation of nitrogen in the soil, the nitrifying agency 

 of bacteria is to be considered the most important. Loss by 

 drainage is generally entirely made up by this natural recu- 

 peration. In fact, while the expenditure of N. per acre by 

 cropping is only about 15 Ibs., loss by drainage under an 

 injudicious treatment may come up to as much as 80 or roo 

 Ibs. per acre, but nitrifying bacteria have been also known to 

 accumulate 80 or 100 Ibs. of N. per acre. On the one hand, a 

 free and moist soil is helpful to nitrification, while on the 

 other, such soil is also liable to loss by drainage in wet 

 weather. A free and open soil kept moist but at the same 

 time protected from rain is therefore most helpful to the 

 generation of nitrates. The presence of some organic matter 

 in the soil is also essential. These conditions naturally 

 prevail in village sites, and old homesteads dug up and used 

 as manure are known to give good results. But artificial 

 nitre-beds under shade may be formed on every farm, and the 

 earth regularly used as manure. Further refined and purified, 

 this nitrous earth, or lona mati t so extensively used as manure 

 in the N.-W. Provinces and parts of Bihar, yields the saltpetre 

 of commerce. 



