VARIATIONS IN PASTURES 141 



is probably the causal factor which accounts both for the greater 

 amount of growth on the fatting fields and its green, broad 

 leafy character. But accepting this more rapid production of 

 available nitrogen as the determining factor giving rise to the 

 herbage, it is still impossible to see from the other deter- 

 minations made why the formation of available nitrogen 

 compounds should be more rapid in the one case than in the 

 other. The difference apparently lies in the nature of the soil 

 organic matter." 



From what has been said, it might be expected that the 

 chemical composition of the herbage from the two kinds of 

 fields would be markedly different especially as regards the 

 percentage of fibre ; but this proved not to be the case. The 

 amount of phosphoric acid and nitrogen is slightly higher 

 in the good that in the poor herbage but the difference is by 

 no means enough to account for the contrasts in feeding value. 

 The conclusion is reached that the ordinary methods of food 

 analysis need much refinement in order to give useful results 

 in such cases as this. 



Attention should be drawn by this investigation to the 

 very important practical consideration that in dealing with 

 the feeding value of pasture grass it is necessary to distinguish 

 between the effect due to the botanical composition of the 

 herbage (the floral type) and that due to the habit of growth. 

 These are dependent on different sets of conditions. The 

 floral type is more influenced by local climate, situation and 

 management than by soil and may vary considerably on the 

 same field from year to year. The habit of growth in the 

 cases here dealt with appears to be chiefly determined by 

 the supply of nitrates and ammonia in the soil, i.e. by the 

 rate of decomposition of the organic matter. 



From the point of view of the soil investigator the work 

 indicates forcibly the limitations of the methods of mechanical 

 analysis. Differences in the physical properties and texture 

 of pasture soils exist which are not revealed by mechanical 

 analysis and, indeed, speaking widely, " soil analysis does not 

 give as clear indications with pasture soils as it does with 

 arable soils." This conclusion receives confirmation in some 

 work now to be referred to. 



The Scouring 1 Lands of Somerset. — A somewhat similar 

 1 Scouring is the farmer's word for acute diarrhoea in cattle. 



