QUALITY OF ILVIILKV (IKOWX ]\ KoTA IK >\ -'.» 



comparatively large i)i()(lucti()n of roots; sinee these are re- 

 moved and since no nitrogen has been supplied, they take away 

 a certain quantity of nitrogen, and theret'ori' exhaust the soil 



Table XXXVI I. — AndrJl Iwtatiun Jiarlci/. Avcrtujc of 5 ycurs 

 (1885, '89, '93, '97, and i901). 



on this plot of its nitrogen to a much greater extent than on 

 Plot 1, which grows a very small root-crop; hence a smalltr 

 barley crop follows the roots on Plot '1. The minerals in 

 fiict do not increase the production of the liarley to an extent 

 which will compensate for the loss of nitrogen in the increase<l 

 root-crop previously brought aliout 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 IMot 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 timls the 

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

 root-crop receives a nitrogenous dressing of rape cake and 

 ammonium-salts; all this nitrogen is rcturiicd to the .-oil 

 in the root-crop which precedes the barley. It will be seen 

 that on the.se five plots the growth of barley is j.roporti(»nal 

 to the amount of nitrogen which may be supposed to be 

 available; all except IMot 1 receive heavy mineral dressings 

 containing both phosphoric acid and potash, yet in tlie 

 absence of nitrogen these minerals on I Mot '1 are not able 



