28 
The results tabulated in Table 27 show that when rotation of crops 
is added to the use of manure, under the conditions of the Missouri 
tests, it is fully as effective in increasing the yields of wheat and 
corn as when the use of manure is conjoined with rotation of crops; 
or, in other words, the relative values of rotation (R) in effecting 
increases in the yields of wheat and corn are 100 per cent and 103.9 
per cent, respectively. In case of oats, the relative value of R is 
*0 
',^&*/A/ &6/& TO A*>9/*£/>ejE 
Fig. 3.— Chart visualizing the comparable yields obtained on wheat, corn, and oats at Columbia, 
Mo., showing the average yields that have baen obtained from cultivation alone, the increase 
effected by combining rotation of crops or the use of fertilizers with cultivation, and the total 
increase effected over cultivation due to the effects of conjoining rotation and the use of fertilizer 
only 33.7 per cent. In case of wheat, the increase effected by adding 
rotation to the use of chemical fertilizer is only 36.4 per cent as 
much as when the use of chemical fertilizer is adcled to rotation. 
The figures in the last two subcolumns show that when the prac- 
tices of crop rotation and the use of fertilizers are conjoined their 
combined effects in increasing crop yields are additive, though in 
each case the combined effects are somewhat less than fully additive. 
Figure 3 represents in chart form the average yields of wheat, corn, 
and oats that have been obtained on the long-time fertility plots at 
