19 



any other fertilizer except sulphate of ammonia, superphosphate, 

 and dissolved bones, the acid of these latter setting free the nitric 

 acid in nitrate of soda, loss in value resulting. The bad effect of 

 nitrate of soda on heavy clay soils is important. When apphed to 

 such soils it is found to increase their stickiness and destroy the 

 tilth. The reason for this is a compUcated one, and only the remedy 

 can be mentioned here, this being to apply a mixture of nitrate of 

 soda and sulphate of ammonia. This mixture must be put on at 

 once, and not allowed to stand long, or the value will be impaired. 

 The great advantage of nitrate of soda is its immediate availability 

 when in the soil, and it is this that makes it so useful in early spring 

 for stimulating a young crop when the weather is unfavourable. 

 When purchasing, a guarantee of 95 per cent, purity should be obtained, 

 this being the usual guarantee of the producer. It is sold in bags 

 and should be carefully stored in a dry place, as it readily absorbs 

 water. It usually contains 15^ per cent, nitrogen, and is sold at 

 about £12 a ton. A good top dressing for a young crop in active 

 growth is I cwt. per acre, or i lb. to 40 square yards. Cabbages, 

 celery, rhubarb, and others not grown for fruit or seed benefit by a 

 dressing of 3-5 lb. to 40 square yards, provided that phosphates and 

 potash are already present. 



Sulphate is also soluble in water, and is grey in colour as a rule ; 

 on being applied to the soil it is quickly absorbed. It should never 

 be mixed with lime or basic slag, as a loss of free ammonia ensues 

 if this is done. The continued use of sulphate of ammonia causes 

 loss of lime to the soil, so a dressing of some form of lime should be 

 given to soils deficient in it. As regards the respective merits of 

 nitrate of soda and sulphate of ammonia, it is seen that the former 

 has an advantage in inducing deep-rooting, so that plants suffer 

 less in time of drought. Moreover, it suffers less from the inroads 

 of bacterial pests, which cannot use it for food so easily as they can 

 sulphate of ammonia.* 



It is usually thought that the latter is better retained by the soil 

 than nitrate of soda, and so is better in wet seasons, but before it 

 can become available it has to be nitrified, and when in that condition 

 is just as liable to be washed down as the other. However, on light 

 soils, provided there is sufficient lime in the soil, sulphate of ammonia 

 is to be preferred to nitrate of soda. 



The price is from £15 to £16 a ton, and it contains about 20 per 

 cent, nitrogen. 



Two manures of recent introduction should be noted here, calcium 

 cyanamide or nitrolim, and nitrate of lime. The first is obtained by 

 combining calcium carbide with nitrogen. It is similar in its action 

 to sulphate of ammonia, and is nearly as effective. As it is very 

 light, and hangs in the air when sown, it is best to mix it with super- 

 phosphate, in the proportion of one of cyanamide to 5 to 10 of super- 

 phosphate, this making it quite easy to handle. As it is said to injure 



* (?)— F. J. C. 



