Manures and Manuring 155 



exported in 1908. The Continent absorbed 1,272,000 tons, the United 

 States 308,000 tons, and the United Kingdom 105,000 tons, about one-half 

 the supply being used for agricultural and horticultural purposes. 



Commercial nitrate of soda contains from 95 to 96 per cent of actual 

 nitrate of soda, the remaining 4 to 5 per cent consisting of moisture, salt, 

 soda, magnesium sulphate, &c. The best samples with 95-per-cent purity 

 contain about 15'6 per cent of nitrogen, this being equivalent to 19 per 

 cent of ammonia. 



Nitrate of soda is a very quick-acting manure that is, it yields up its 

 nitrogen soon after application and especially after a shower of rain. It 

 should therefore only be applied to soil which is carrying a crop in full 

 growth, and which shows by the colour of its foliage that a dressing would 

 be beneficial. As growth is most rapid in spring and summer, these are the 

 best seasons for applying nitrate of soda. As an autumn or winter dressing 

 it would be practically wasted. The quantity given will vary from 1 cwt. 

 to 2 cwt. per acre, or, roughly, f Ib. to 1| Ib. to every square rod or pole 

 of ground. As a stimulant in conjunction with organic manures already in 

 the soil, nitrate of soda is excellent for Cabbage crops, including Turnips 

 and Kohl Rabi, as well as for Beet, Spinach, &c. It is only rarely necessary 

 to apply it to leguminous crops like Peas and Beans, as these are capable of 

 securing their own supplies of nitrogen from the atmosphere. Perhaps the 

 best way to use nitrate of soda is as a topdressing, afterwards working it 

 into the soil with the hoe; or for pot plants by dissolving about 1 oz. in 

 1 gal. of water. If used dry, a mere pinch as much as will cover a three- 

 penny piece is quite sufficient for plants in 5-in. pots. 



Nitrate of soda may be used with basic slag, but should never be mixed 

 with sulphate of ammonia or kainit; and it can be only safely mixed in 

 small quantities with superphosphate of lime, owing to the danger of 

 decomposition. 



Nitrate of Potash. This is popularly known as "saltpetre "or "nitre". 

 Owing to its high price it is very little used by farmers and gardeners. It 

 is not only rich in nitrogen, but also in potash, and should therefore be 

 regarded more as a potassic manure. When of 85-per-cent purity it con- 

 tains 14 per cent of nitrogen and 40 per cent of potash. 



Sulphate of Ammonia. This resembles nitrate of soda somewhat in 

 appearance but is rather coarser in the crystals. It is a compound 

 of ammonia and sulphuric acid, and is obtained from the ammonia liquor 

 of gasworks, ironworks, &c. In a pure state it contains 25'8 per cent of 

 ammonia, equal to 21*2 per cent of nitrogen. A pinch of unadulterated 

 sulphate of ammonia will vaporize completely on a red-hot surface. The 

 commercial product, however, of about 95-per-cent purity contains 24'5 per 

 cent of ammonia, equal to 20'2 per cent of nitrogen. It may be used in 

 the same way as nitrate of soda, but is more lasting in its effects. It should 

 not be mixed with nitrate of soda, basic slag, or with lime or chalk, as these 

 would liberate the ammonia and cause it to be lost. 



The production of sulphate of ammonia has increased from 42,000 tons 



