m] SULPHATE OF AMMONIA 23 



the increases may not be worth the cost. Specially valuable 

 crops well suited to nitrate, e.g. early cabbages and broccoli, may 

 receive these larger dressings, and in Cornwall as much as 10 cwts 

 per acre is sometimes used. In such cases the nitrate should go 

 on in two or three lots, and not all at once. 



Nitrate of soda easily washes away and will not remain in the 

 soil over a wet winter; any that is not used by the crop in one 

 season must be given up as lost. But when used as a spring 

 dressing the risk of loss is only very small, unless one has the 

 misfortune to put it on just in front of a long continued spell of 

 heavy rain. 



Nitrate of lime, where obtainable, has proved very valuable 

 as a fertiliser. It resembles nitrate of soda in fertilising action, 

 but seems to have no bad effect on the tilth. 



Sulphate of ammonia. Next to the nitrates this is the quickest 

 acting nitrogenous manure : it has to be changed into nitrates in 

 the soil, but this does not take long under favourable circum- 

 stances, and in an ordinary way, unless it is desired to act on the 

 plant at once, there is little to choose between sulphate of ammonia 

 and nitrate of soda. Very careful comparisons have shown that 

 the sulphate is not quite as good as the nitrate, its average return 

 being about 80, when that of nitrate is 100 ; on the other hand it 

 is often cheaper than nitrate. Sulphate of ammonia has no bad 

 effect on the tilth, but rather the contrary, indeed as already 

 stated it serves to correct any harm done by nitrate of soda. 



It is the chief constituent of soot 1 , and can be used in exactly 

 the same way as soot: 1 to 2 cwts per acre form a suitable 

 dressing. It can be used either as a top dressing or drilled in 

 with superphosphate. Like nitrate of soda it cannot be expected 

 to remain in the soil over a whole season, and any not taken up 

 by the growing crop must be counted as lost. It is rather safer 

 than nitrate of soda for use in winter or very early spring as it 

 will survive considerable rainfall so long as the soil is not warm 

 enough to induce rapid nitrification. As in the case of nitrate 

 of soda the larger the dressing the greater the increase in crop: 

 this is shown in the Kothamsted experiments with wheat (p. 44 



1 In some samples muriate of ammonia is said to be the chief constituent, but 

 the same remark applies. 



