BARLEY. 85 



with continued and considerable deficiency of rain, the com- 

 bination further restricting growth, and bringing on prema- 

 ture ripening. 



Influence of Exhaustion, Manures, and Variations of Season, 

 on the Composition of the Barley Crops. 



In the case of wheat it was found that the supplies within cpmposi- 

 the soil — both of nitrogen and of mineral constituents — had [^l^Jt 

 a very direct influence on the composition or the crop so long jiuencedty 

 as it was only in the vegetative stage ; but that there was, exhaustion, 



-o a\. "A- if At. manures, 



nevertheless, very great uniformity in the composition ot the and season. 

 final product of the plant — the seed — provided only that it 

 was perfectly matured. The composition of the straw, how- 

 ever, showed a very direct connection with the supplies by 

 the soil. The composition of the grain was, on the other 

 hand, materially influenced by variations of season. But 

 variations of season obviously have great influence on the 

 condition of maturation; whilst difference in maturation 

 implies difference in organic composition — the amount of 

 carbohydrates (starch especially) formed. In fact, such vari- 

 ations in composition imply deviations from perfect and 

 normal maturation; and such deviations are associated not 

 only with differences in the organic composition — the relation 

 of the nitrogenous to the non-nitrogenous constituents — but 

 with differences in the mineral composition also. 



It follows that variations in the composition of the final 

 and very definite product — the seed — should be much more 

 clearly traceable to variations of seasou than to variations in 

 the supplies within the soil — that is, than to exhaustion or 

 manures. This was found to be very strikingly so in the case 

 of wheat, and we have now to consider how far it is so with 

 its near ally — barley. 



The results given in Table 27 (p. 86) forcibly illustrate the Table SB 

 much greater influence of variations of season than of manures ex P lained ' 

 on the composition of barley grain. Many complete analyses 

 of the ash of the grain (and also the straw), grown by different 

 manures, and in different seasons, have been made ; and taking 

 for illustration the important and characteristic constituents, 

 potash and phosphoric acid, the table shows, for three very 

 different manurial conditions, the highest, the lowest, and the 

 mean amounts, of potash and phosphoric acid, in 1000 parts 

 of the dry substance of the grain, and of the straw, in different 

 seasons. The manurial conditions selected are — 1, without 

 manure ; 2, with farmyard manure ; 3, mixed mineral manure 

 (including potash) and ammonium-salts. 



First as to the amounts of potash in 1000 parts dry sub- 



