58 RESULTS WITH BARLEY 



assimilation by the plant a certain amount of soil nitrogen 

 which remains unavailable when wheat is grown. The barley 

 is thus better supplied with soil nitrogen, and can therefore 

 employ profitably only a smaller quantity of nitrogenous 

 manure. A second reason lies in the better utilisation of the 

 ammonia salt employed in the barley field : this point has been 

 already fully noticed. 



Influence of Ash Constituents. On the Rothamsted 

 soil, a full return from the use of ammonia salts for barley 

 is only obtained when superphosphate is also applied. The 

 addition of 3^- cwts. of superphosphate to 200 Ibs. of ammonia 

 salts has on an average increased the produce by 13-7 bushels. 

 The addition of superphosphate has indeed been far more 

 effective with barley than with wheat. On the other hand, the 

 alkalies which had such a considerable effect on the wheat 

 crop produced at first no increase of barley, and it was only 

 after the first thirty years of the experiment that the produce 

 of plot 4A, receiving alkalies and superphosphate, became 

 distinctly larger than that of plot 2A, receiving only super- 

 phosphate with the ammonia. We shall see presently, how- 

 ever, that the alkalies have for a considerable time much 

 influenced the quality of the grain. 



The time of ripening of the barley on the various plots is 

 very different, and is largely determined by the supply of ash 

 constituents. The produce of the most complete and best 

 balanced manure is always that which ripens earliest and most 

 thoroughly, provided the manure is not used in excessive 

 quantity. With ammonia salts alone ripening is delayed. 

 When superphosphate is added to the ammonia ripening is 

 much accelerated. In the later years of the experiment the 

 ripening has been earliest and most complete when both 

 alkalies and superphosphate have been used with the am- 

 monia. 



Influence of Climate. Following the mode of discussion 

 adopted when considering the wheat experiments, we give in 

 Table XIV (p. 59) the average produce of barley upon the 

 plots already mentioned in the five seasons of greatest produce, 

 1854, l8 57> l86 3, 1864, and 1880. 



