EFFECT OF MAXU1M< UKSIDTES ON WIIIAT ]W 



The wheat, wliifli comes last in the rotation, still >ho\\s 

 some effect for tlie nitroucii applied three years jM-cvioiisIy. If 

 we consider the fallow portions only, there aiv nearly :) hnsh.-U 

 more i^rain pro(hiced by the residue of the niti-ou'cnoiis 

 mamiring, so dependent is the wheat crop upon a sujiplv of 

 nitrogen. On the portions which ui'ow heans oi- clover tli.- 

 wheat crop gains so much from the nitrogenous material 

 left by the stubble of these leguminous crops that the effect 

 of the previous nitrogenous manuring is no longer apparent, 

 the average crop being actually highest on the portions 

 receiving only minerals, thus corresponding with the varying 

 yields of the previous leguminous crops rather than with the 

 direct nitrogenous manuring. 



U nman u red 



Minerals only, 

 no Nitrogen 



Connplete Manure 



Fin. 42.— Effect of Manure upon Crops thrown in Rotition. Totii! I'roducc. Averajjes 

 of Five Courses (1884-1903). Swedes in 100 cwt. ; Barlt-y find Wtu-at in luOO lb. ; 

 and Clover in 10 cwt. 



Fig. 42 shows in a gTaphic form the effect of the.se three 

 systems — no manm-e, minerals without nitrogen, and a complete 

 manure — on the successive crops in the rotation. 



