208 The Rothamsted Grass Experiments. 



gramineous herbage, the actual quantity of the second crop 

 is small, and its proportion to the first little more than half 

 as much as without manure, and only about two-thirds as 

 much as with the mineral manure alone. 



On plot 14 the first crops averaged more still ; they, also, 

 consisted almost exclusively of free-growing (though chiefly 

 other) grasses, and they comprised but few species. With 

 these characters, the second crops averaged even rather less 

 than with the ammonia- salts, and bore a smaller proportion 

 to the first. 



In the case of plot 11, with double the amount of 

 ammonia-salts of plot 9, there were upon the whole still 

 larger first crops, and almost exclusively gramineous herbage, 

 which contained, however, a very abnormally high percentage 

 of nitrogen, and, with the obvious excess available, there is 

 here more second crop, and a higher proportion of second 

 crop to first, than with the smaller amount of nitrogenous 

 manure. There is, moreover, a tendency to a greater amount, 

 and proportion, of second crop in the later years. 



The general result is that, when (with mineral manure) 

 active nitrogenous manures are used, but not in excessive 

 amount, the increase of the first crop will, in favourable 

 seasons, be such as to leave comparatively little available 

 nitrogenous residue for the second crop ; whilst, the produce 

 under such circumstances being characteristically gramineous, 

 and comprising comparatively few species, the condition of 

 the herbage is not very favourable for subsequent growth. 

 The percentage of both mineral matter and nitrogen is 

 generally, however, much higher in the dry substance of the 

 second and less matured produce, than in that of the first 

 and more matured, so that the removal of the second crops 

 is a considerably greater drain upon the resources of the soil 

 than might be suspected from the comparatively small 

 amounts of the produce. It is evident, too, that the actual 

 and relative amounts of second crop depend not only on the 

 balance of available coustituents remaining within the soil, 



