410 



ANNUAL REPORT OF THiE 



Off. Doc. 



limed and has until recently shown little need for the use of this ma- 

 terial. Great gains from liming should from this fact, not have 

 been expected. It is at once apparent that the frequent liming at 

 the rate of 50 bushels of stone lime per acre during the long period 

 of these experiments, is an extreme test of the effects of the method. 



The actual quantities of lime applied in the two forms during a 

 rotation are not far different. The cost of the lime was 5 cents per 

 bushel, equivalent to |2.50 per acre, while the cost of the fine crjiished 

 limestone was |6.50 per ton on the average, equivalent to |26 per 

 acre during a rotation. This cost may be greatly reduced by pur- 

 chasing the crushed stone in large quantities, but will remain much 

 greater than the cost of the fine powder obtained by slaking burnt 

 lime. 



The quantities of the several crops obtained on the two lots of 

 four plots each, receiving the several treatments, during twenty 

 years, or five complete rotations, the yield of the adjacent unfertil- 

 ized plots being taken as 100, were: 



Combined Yields for Five Eotations. 



I 



I 



fs a 



Com: 



Bars 



Entire crop, 

 Oats: 



Grain 



Entire crop, 

 Wheat: 



Grain 



Entire crop. 

 Hay 



92 

 94.0 



102.8 

 119.0 



110.4 

 U2.0 

 10S.6 



That is to say, in each case the yields with the carbonate of lime 

 showed superiority under the conditions of this experiment over 

 those following an equivalent application of caustic lime. After 

 each of these treatments, however, the corn yield was depressed. 

 The yield of threshed oats was depressed by the lime and little 

 affected by the carbonate; but both increased the total crop, the car- 

 bonate most. Both treatments were followed by an increased yield 

 of wheat — grain and straw — a slight advantage again appearing on 

 the side of the carbonate. Lime greatly depressed the following hay 

 crop, however, while carbonate slightly increased it. 



The total application of lime in five rotations was very large, 

 amounting to 10 tons per acre, equivalent to 0.5 per cent, of this 

 soil taken to the depth of 8 inches. So that, if the lime were not 

 largely removed by descent to subsoil or by solution in drain waters, 

 nearly 1 per cent, of carbonate of lime could be formed from it in the 

 surface soil. This percentage is not usually considered high enough 

 to threaten injury to crops on heavy loams. 



It is desirable, nevertheless, to compare the effects of the lime and 



