No. 7. 



DEPARTMENT OF AGRICULTURE. 



411 



carbonate treatments during the first and last rotations, to observe 

 whether any action is manifest as a result of the accumulation of 

 calcium carbonate in the soil. The comparative yields for these ro- 

 tations, expressed in ratio with the yields of the adjacent unfertil- 

 ized plots for the same years, are given below: 



Lime. 



fa 



Carbonate. 



cd 

 o 



Corn: 



Ears 



Entire crop, 

 Oats: 



Grain 



Entire crop, 

 Wheat: 



Grain 



Elntire crop, 

 Hay 



91.0 

 91.4 



94.3 

 99.5 



94.4 

 92.7 



87.8 



82.8 

 88.1 



83.6 

 109.2 



108.9 



109.9 



95.9 



110.6 

 115.0 



104.0 

 115.6 



86.2 

 88.5 

 98.6 



112.4 

 110.6 



110.5 

 118.8 



119.8 

 122.2 

 118.0 



Judging from these data the heavy applications of lime injured 

 corn and oat grain yields more after the first rotation, but the cropi 

 of intermediate rotations show that it was not a distinctly increasing 

 degree. On the other hand, the use of lime depressed the wheat yield 

 at first, but increased it in later rotations and injured hay less. The 

 carbonate shows little change in effect upon corn and oats during 

 later rotations, but depressed the wheat and hay yields at first and 

 mcreased them in later years. 



Certain crop peculiarities are apparent in consequence of these 

 ireatmentb: The leaves of corn on the carbonate plots have a healthy 

 green coloi ; those of [ilauty on the lime plots are yellow when young, 

 and striped with deep red colors when mature. On both sets of 

 plots clover far exceeds timothy; the ratios between ear and stalk 

 show a slight increase of stalk in corn after either treatment, prac- 

 tically no change in case of wheat, but a very marked increase of oat 

 straw in proportion to the grain, an increase somewhat the more 

 pronounced with the lime treatment, but visible with the carbonate 

 treatment also. 



The crop results justify the statement that the use of lime in the 

 manner adopted for these experiments and under the conditions pre- 

 viously mentioned cause a net decrease rather than a gain in pro- 

 duction; whereas, the carbonate of lime exhibited a slight increase, 

 but entirely insufficient to pay for the cost of the carbonate applied. 



Partial analyses of the soils of these plots made 18 years after the 

 experiments were begun showed the presence in the soil treated with 

 carbonate of lime, of practically the ^ame amount of organic carbon 

 as in the unfertilized soil, and somewhat less active humus; whereas, 

 the limed plots showed one-eighth less organic carbon and one- 

 tenth less active humus than the unfertilized plots. That is to say, 

 the lime used in excess tended clearly to depress the humus supply 



