QUALITY OF BARLEY GROWN IN ROTATION 89 



as to quality, taking an average of the five courses from 1885 

 to 1901. The first plot has been wholly unmanured, and all 

 the crops in the rotation are removed from the land; the 

 average production is, however, higher than on the unmanured 

 plots growing barley continuously, because of the fallowing the 

 land receives. When minerals only are applied to the root- 

 crop on Plot 2 (roots are grown immediately before the barley), 

 there results a comparatively large production of roots ; since 

 these are removed and since no nitrogen has been supplied, 



TABLE XXXVII. Aydell Rotation Barley. Average of 5 years 

 (1885, '89, '93, '97, and 1901). 



These plots have been differently numbered since 1904. The present numbers are : 



Plot 5 (unmanured fallow) ; Plot 3 (minerals fallow) ; Plot 4 (minerals clover). 



All roots are now carted. 



they take away a certain quantity of nitrogen, and therefore 

 exhaust the soil on this plot of its nitrogen to a much greater 

 extent than on Plot 1, which grows a very small root-crop ; 

 hence a smaller barley crop follows the roots on Plot 2. The 

 minerals in fact do not increase the production of the barley to 

 an extent which will compensate for the loss of nitrogen in the 

 increased root-crop previously brought about by the minerals. 



On Plot 3, however, clover (or beans) is grown as the third 

 crop in the rotation, and by collecting nitrogen from the atmos- 

 phere leaves behind a residue in the soil which is still available 

 for the barley crop coming three years later. On Plot 4 there 

 is a still greater supply of nitrogen, for not only is a leguminous 

 crop grown, but also the root-crop preceding the clover is 

 returned to the land. On Plot 5 the barley finds the 

 maximum amount of nitrogen ; here clover is grown, and the 



