162 EXPERIMENTS UPON GRASS LAND 



quality as that grown with mineral manures alone, because the 

 large amounts of nitrogen have so stimulated the development 

 of the grasses that leguminous plants have disappeared entirely, 

 and even the weeds are crowded out. In 1903 the latter formed 

 only a trifle more than 4 per cent, of the herbage on Plot 9, 

 and were barely perceptible on Plot 11-1, as may be seen in the 

 photographs, Figs. 24 and 25, representing turf from these plots. 

 The dominant grasses on Plot 9 consist of False Oat Grass, 

 Smooth-stalked Meadow Grass, Sweet Vernal, and Sheep's 

 Fescue ; Meadow Foxtail, Cocksfoot, Yorkshire Fog, and 

 Bent Grass constituting practically the rest of the herbage. 

 On Plot 11-1 there is every sign that an excess of nitrogen has 

 been employed ; the vegetation is very rank and soft, and tends 

 to grow in tufts with bare patches between ; the smaller grasses 

 are almost wholly crowded out, and the coarse vegetation is 

 generally laid and begins to rot at the bottom before the grass 

 is ready to cut. Owing to the great competition of the strong- 

 growing grasses the numl:)er of species on this plot has been 

 reduced to a minimum ; 97 per cent, of the herbage is made 

 up of three species alone — False Oat Grass, Meadow Foxtail, 

 and Yorkshire Fog, the latter repTesenting 45 per cent, of the 

 whole herbage. In the earher years of the experiment this 

 latter grass was by no means so prominent. As late as 1872 

 it only formed 10 per cent, of the herbage, while more than 

 39 per cent, was composed of Cocksfoot, which has now 

 practically disappeared. The replacement of Cocksfoot by 

 Yorkshire Fog seems to have been coincident with the abandon- 

 ment of the practice of grazing the aftermath ; the custom of 

 late years has been to cut it. 



On Plot 11-2 the same manure is employed as on Plot 11-1, 

 with the addition of 400 lb. of silicate of soda. The silicate of 

 soda has resulted in a considerable increase of crop, which has 

 averaged as much as 72 cwt. for the whole period ; the grass 

 on this part of the plot is also more healthy and uniform, and 

 ripens earlier. The effect of the silicate of soda must probably 

 be attributed to the soda base rather than to the silica : for with 



