BARLEY. 69 



crops are very different. For wheat a comparatively heavy 

 soil is adapted ; and a fine tilth, encouraging superficial root- 

 development, is not desirable. For barley, on the other hand, 

 a comparatively light soil is more appropriate, and a fine tilth 

 is of great importance. In other words, with the character- 

 istic habit of growth of the plant, and the short period at its 

 command for root-development, a very permeable surface-soil 

 is a desideratum. 



In these facts we have the indication that wheat acquires Root- 

 a much greater root-range, and consequently a command of ™h%riatd 

 the resources of a more extended range of both soil and sub- barley. 

 soil ; whilst barley must, in a greater degree, be dependent 

 on the supplies within the surface-soil, and so be the more 

 susceptible to the influence of the exhaustion, or the supplies, 

 within the surface-soil. 



Bearing these various points in mind, we may now turn to 

 the results of long-continued field experiments on the growth 

 of barley, by different manures, and in different seasons, and 

 to the evidence of the collateral laboratory investigations re- 

 lating to the subject 



The Field Experiments on Barley, 



The Eothamsted field experiments on barley were com- Rotham- 

 menced in 1852 — that is, eight years later than those on ^Son*" 

 wheat, but at the same time as that at which the arrangement barley. 

 of the plots in the experimental wheat - field devoted to 

 chemical or artificial manures became more systematic and 

 permanent. 



The barley crop of 1894 was, therefore, the forty -third Piano/ 

 in succession on the same land. There are nearly thirty JJ^JF 8 ™" 

 experimental plots. Two have been unmanured from the 

 commencement. One has received farmyard manure every 

 year, or rather one-half of it has, for, after twenty years, the 

 plot was divided ; one half being still annually manured as 

 before, and the other half then left unmanured, to test the 

 effects of the unexhausted residue of the twenty years' pre- 

 vious applications of farmyard manure. The other plots have 

 annually received artificial manures, for the most part the 

 same year after year from the commencement ; but there 

 have been a few changes, some of which will be explained as 

 we proceed. 



Results without Manure, and with Farmyard Manure. 



Table 21 (p. 70) gives, both without manure and with farm- Table 21 

 yard manure, the produce of grain per acre in each of the forty- ^tamerf. 



