174 THE PRINCIPLES OF 



generically, as weedy or miscellaneous herbage. Now in this 

 mixed population of a permanent pasture, you have, as 

 you might expect, a rather different effect produced by the 

 use of various fertilizing substances ; and I may confess that 

 upon permanent pastures you get very extraordinary results 

 by the application of those substances of lesser importance, 

 such as sulphate of potash, sulphate of soda, and sulphate of 

 magnesia, especially when they are assisted with the two 

 better recognized substances superphosphate and ammonia 

 salts. By far the best yield is obtained by this combination of 

 all the substances which are required. In one case the yield 

 of hay goes up to 4 tons 8 cwt. to the acre, taking both first and 

 second cuttings that very large yield being derived from 

 the use of sulphates of soda and magnesia, superphosphates, 

 and 600 Ibs. of ammonia salts, and for the first time silicate 

 of soda. 



Not only is there a very large variety of plants and 

 great variety of requirements, but we must remember that 

 the produce consists not only of grain or of roots, but of the 

 entire stem and flower. There is a very large amount of 

 silica removed from a meadow or pasture soil, and it appears 

 as if this were a case in which the application of silica in a 

 soluble and available form can be made with good effect. 

 In these experiments which have been continued every 

 season from 1856, we find the following average results 

 during eleven years, from 1876 to 1886, taking both first 

 and second crops into the total amounts per acre. The con- 

 tinuously unmanured plots have yielded upon an average 27 cwt. 

 of hay per acre (18 cwt. for the first cut, and 9 cwt. for the 

 second cut) ; superphosphate of lime at the rate of 3 J cwt. per 

 acre, has only pushed up the yield to 28 J cwt., showing once more 

 the small effect of superphosphate upon gramineous herbage. 



Mixed mineral manures composed of sulphate of potash, 

 sulphate of soda, sulphate of magnesia, and superphosphates, 



