178 The Bothamsted Grass Experiments. 



few prominent miscellaneous species, whilst the flora was not 

 very materially affected by the discontinuance of the potash ; 

 though, without the potash, the gramineous herbage showed 

 very different, and much inferior, characters of development. 

 Without ammonia, on the other hand, and with the potash, 

 the produce contained a large proportion of leguminous 

 herbage ; and the most prominent effect of the discontinu- 

 ance of the potash was the reduction of the leguminous her- 

 bage to a very insignificant amount, whilst, at the same time, 

 the character of development of the grasses was deteriorated. 



The importance of a liberal available supply of potash 

 within the soil in order to grow large, properly developed, and 

 well matured hay crops, is now made evident. With a fairly 

 mixed herbage, and only moderate nitrogenous manuring, a 

 liberal supply of potash will increase, or a deficiency of it will 

 greatly diminish, the growth of leguminous plants ; whilst, 

 at the same time, both the quantity and the character of 

 growth of the gramineous herbage will be affected. Or, with 

 a predominantly gramineous herbage, and full supply of 

 nitrogen, a deficient supply of potash will diminish the 

 amount of produce and consequently the efficiency of the 

 nitrogenous manure, and it will, moreover, lead to a deterio- 

 tion in the character of the growth. 



14. Mixed Mineral Manure alone 7 years ; succeeding 

 Ammonia-salts alone 13 years : Plot 6. The figures in Table 

 XLIV. illustrate the effects of applying the mixed mineral 

 manure, including potash, for seven years in succession on a 

 plot which had received ammonia-salts, without mineral 

 manure, in each of the thirteen preceding seasons (with saw- 

 dust in addition the first seven years). The comparisons are 

 with plot 5, which received the same quantity of ammonia- 

 salts (without sawdust) in each of the twenty years as was 

 applied to plot 6 during the first thirteen years ; and with 

 plot 7, which received the same mixed mineral manure 

 throughout the twenty years as plot 6 received during the 

 last seven years. 



