June 15,1925 Effect of Crops on Yields of Succeeding Crops in Rotation 1129 
Fig. 15 .—Effects of tobacco, potatoes, and corn on yield of wheat when soil¬ 
ing crops are in the rotation. In the early years of the test potatoes showed 
a markedly beneficial effect as compared with tobacco, but in subsequent 
years the difference between the effects of tobacco and potatoes have been 
much smaller. Corn has shown a depressing action throughout the test 
Fig. 16.—Effects of tobacco, potatoes, and corn on yield of oats when soiling 
crops are in the rotation. The outstanding feature is the marked upward 
trend in yield of oats after tobacco, the yield in later years of the test almost 
equaling that after potatoes; the progressive gain after corn from the residual 
effects of the soiling crops is comparatively small 
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Fig. 17 .—Effects of tobacco, potatoes, and corn on yield of rye when soiling 
crops areinthg rotation. In comparison with corn, potatoes have shown 
a strikingly beneficial effect on the rye. This was true also of the potatoes 
in comparison with tobacco in the early years of the test, while, more re¬ 
cently, the growth of rye after tobacco has approached more nearly that 
after potatoes 
