332 Results of Experiments on Permanent Grass-la nd. 



the same time obvious, that when the more functionally important 

 constituents are available in relative abundance, those which are of less 

 importance in this respect were taken up and retained in less amount 

 than they otherwise would be ; the result being determined in great 

 measure by the character of growth induced. 



For example, if potash be liberally available the produce is much 

 more stemmy, and the amount of soda, of lime, and to some extent of 

 magnesia also, will be less relatively to the potash. In defect of suffi- 

 cient potash, on the other hand, more of soda, or of lime, or of both, 

 will be taken up and retained ; but the herbage will at the same time 

 be more leafy and immature. That is to say, the constituents are not 

 mutually replaceable in the processes of growth, but accordingly as the 

 one or the other predominates, so will the product of growth be 

 different. 



There can be no doubt, that luxuriance or vegetative activity is 

 intimately associated with the amount of nitrogen available and taken 

 up. Further, it may be stated that chlorophyll formation to a great 

 extent follows nitrogen assimilation. But the results relating to the 

 increased amount of non- nitrogenous substance yielded in the mixed 

 herbage under the influence of the various manures clearly indicated that 

 the nitrogen being taken up, and the chlorophyll formed, the carbon 

 assimilation, and the carbohydrate formation, depended essentially on 

 the amounts of potash available. It may be stated as a matter of 

 fact that, in practical agriculture, artificial nitrogenous manures are 

 chiefly used for crops containing a comparatively low percentage of 

 nitrogen in their dry substance, and yielding comparatively low 

 amounts of nitrogen per acre. Indeed, they are mainly used for the 

 increased production of the non-nitrogenous bodies — the carbohydrates 

 — starch and cellulose in the cereals, starch in potatoes, and sugar in 

 the sugar-cane and in root crops, for example. And now, in the case 

 of the mixed herbage of grass land, it was seen that, provided the 

 mineral constituents, and especially potash, were abundantly available, 

 a characteristic effect of nitrogenous manures was to increase the 

 production of the non-nitrogenous bodies. 



