Effect of Superphosphate of Lime alone. 155 



pared with the first, was greater with the superphosphate 

 than without manure ; whereas, with the mixed mineral 

 manure there was not a reduction but an increase of all three 

 during the second period. 



The number and relative predominance of the plant species 

 was much the same as without manure. The most noticeable 

 changes were a rather greater weight of total gramineous 

 herbage, due mainly to more of ripening tendency ; a reduc- 

 tion in weight of Leguminosae, with a prevalence of Lathyrus 

 pratensis rather than that of Lotus corniculatus ; and an 

 increase in weight of miscellaneous herbage, with a greater 

 prevalence especially of Ranunculus repens and E. bulbosus 

 (buttercups), Achillea Millefolium (yarrow), and Rumex 

 Acetosa (sorrel). 



Of the constituents supplied in the superphosphate, a little 

 more of lime and magnesia, once and a half as much 

 sulphuric acid, and nearly twice as much phosphoric acid, 

 were taken up under its influence as without manure. Of 

 potash and silica very little more were taken up from the 

 soil than without manure, but the increase of soda was some- 

 what greater. 



The superphosphate enabled the plants to draw somewhat 

 more largely on the resources of the soil, especially at first, 

 but the small increased available supply under its influence 

 rapidly diminished. A comparison of the produce by the 

 superphosphate alone, with that by the mixed mineral 

 manure, clearly shows that it was neither exclusively, nor 

 even mainly, to the phosphoric acid which the latter con- 

 tained that the results it yielded were due. 



6. Mixed mineral manure, with and without potash : Plots 7 

 and 8. During the first six years (1856-61), plots 7 and 8 each 

 received the " mixed mineral manure," comprising super- 

 phosphate of lime, and sulphates of potash, soda, and 

 magnesia, the only difference being that during those years, 

 and in 1862, plot 8 also received 20001b. of sawdust per acre 

 per annum. From 1862 inclusive, plot 7 has continued to 



