412 ANNUAL REPORT OF THE Off. Doc. 



in the soil. Nevertheless, the rate of decrease was very slow, and 

 where manure was used in moderate quantities with lime the humus 

 content did not diminish. 



In the case of the nitrogen, likewise, the carbonate plot shows 

 a distinct gain over the unfertilized plots, whereas, the limed plot 

 exhibits a deficiency amounting to one-eighteenth of the entire quan- 

 tity in the unfertilized soil — a decrease readily accounted for when 

 the liberation of ammonia and more rapid destruction of humus in 

 limed soils are considered. When, however, manure was used with 

 lime, the soil showed a very pronounced gain in nitrogen far exceed- 

 ing the proportion of gain in humus in the same plots. That is to 

 say, in the manure, as in the soil, the influence of lime leads to a 

 more rapid destruction of carbonaceous than of nitrogeneous mat- 

 ter. 



To conclude, the use of crushed limestone in large quantities ap- 

 plied biennially was slightly advantageous, both as regards crop 

 yield and influence upon the humus and nitrogen supplies of the 

 soil, while the use of corresponding quantities of lime, applied every 

 four years, led to diminished crop yields, other than those of wheat, 

 and to a slight but appreciable diminution of humus and nitrogen 

 in the soils. It is probable that the relative gain in the soil nitro- 

 gen and the crop increase were collectively sufficient in this case to 

 pay the extra cost of the carbonate. 



Considering, however, the fact that the use of lime in these ex- 

 periments was highly excessive, that the soil had, when the experi- 

 ments began, no particular need for the addition of lime, and that 

 the losses of soil and crop from its use were not very great, it is im- 

 probable that the results above stated would warrant Pennsylvania 

 farmers who are tilling and cropping heavy clays and loams in sub- 

 stituting the more expensive and less perfectly distributable crushed 

 limestone for the much more cheaply and perfectly subdivided, 

 slaked lime used in equivalent, moderate quantities. 



A Member: Then you do not advocate the free use of lime? 



DR. FREAR: Not always; but I think the question resolves itself 

 into this: whether the soil contains sufficient lime for the amount of 

 humus that is in it, and the texture. Now, in light soils there is not 

 so much danger in the use of life, but we have very few soils and it 

 is a common experience that we cannot use much lime to advantage. 

 I might refer to the soils of Rhode Island and of France as examples 

 of the tendency to decrease the product by the use of the lime. 



MR. STOUT: Do we apply enough fertilizer in the shape of lime 

 for the use of our crops, whether we use the raw rock or the acidu- 

 lated fertilizer? 



DR. FREAR: Yes. I think I might answer that the average far- 

 mer of Pennsylvania is applying to the land in one form or another 

 practically all the calcium which the crops remove. We have to con- 

 sider the tilth of the soil, and the amount of lime carbonates in the 

 soil also in this connection and not put on the lime for the sole pur- 

 pose of applying it. 



