EFFECT OF MANURE RESIDUES ON WHEAT 199 



hardly to be seen, on the other plots which receive nitrogen 

 for the Swedes, although no nitrogen has been applied during 

 the years in which the plant in question is growing. 



The wheat, which comes last in the rotation, still shows 

 some effect for the nitrogen applied three years previously. If 

 we consider the fallow portions only, there are about 3 bushels 

 more grain produced by the residue of the nitrogenous 

 manuring, so dependent is the wheat crop upon a supply of 



Unmanured . 



Minerals only, 

 no Nitrogen. 



Complete Manure 



FIG. 42. Effect of Manure upon Crops grown in Rotation. Total Produce. Averages 

 of Five Courses (1884-1903). Swedes in 100 cwt. ; Barley and Wheat in 1000 Ib. ; 

 and Clover in 10 cwt. ' 



nitrogen. On the portions which grow beans or clover the 

 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. 



Fig. 42 shows in a graphic form the effect of these three 



