90 THE SOIL OF THE FARM. 



at present prices the nitrate is the cheaper fertilizer of 

 the two. 



** The commercial value of these two substances is 

 based entirely upon the amount of nitrogen which tliey 

 contain. Having said this, I by no means wish to be un- 

 derstood," says Sir J. B. Lawes, '' that the action of the 

 two substances is the same. Both supply the plant Avith 

 nitric acid, but with the sulphate of ammonia, the forma- 

 tion of nitrate of lime is attended with the formation of 

 sulphate of lime, and with a considerable removal of the 

 soluble sulphate of lime in the soil. Where nitrate of 

 soda is used, an alkali is liberated, which has a decom- 

 posing action upon the minerals of the soil. In cases 

 where sufficient potash is not available, large amounts of 

 soda are also taken up by 'plants when manured with 

 nitrate of soda. We have found soda very largely in pas- 

 ture sugar beets and mangels, but not in potatoes. 



"For some reason which I am unable to exi^lain, the 

 application of nitrate to leguminous plants is more favor- 

 able to their growth than the application of salts of 

 ammonia. The herbage of a permanent pasture, where 

 nitrate of soda alone, in one case, and with the addition 

 of minerals in another, is applied every year, is of a 

 totally distinct character from the herbage where salts of 

 ammonia are applied alone, in one case, and with miner- 

 als in another. I think, too, we have evidence to show 

 that the organic matter in the soil is reduced more 

 rapidly by nitrate than by ammonia." 



Of the two manures, nitrate of soda answers best in a 

 dry season, and sul|)hate of ammonia in a wet one. They 

 can only be economically applied to land with a growing 

 croj) ready to seize on tliem. It is therefore never ad- 

 visable, even in a dry spring, to sow these soluble manures 

 as early as the seed. Grain crops should be well above 

 ground, and root crops should be at least thinned and set 

 out, before either ammonia salts or nitrates are applied. 



