14 The Bulletin 



Experiment Station Record, vol. 28, page 62-i, Moores, Hampton, 

 and Hunter of the Tennessee Station, in their investigations of the 

 effect of caustic lime and green manure on the content of nitrogen and 

 humus in the soil, state : "Where the cowpea crop was turned under each 

 year for five years there was found, at the end of that time, on the 

 unlimed sections, an increase of 3.79 per cent of humus, as an average 

 of the 12 plats, but neither gain nor loss on the corresponding limed 

 sections. Where the cowpea crop was removed for five years there was 

 an apparent gain of 2.38 per cent on the unlimed section as an average 

 of the four plats, but an apparent loss of 3.17 per cent in the correspond- 

 ing limed sections." Where caustic lime was used and the cowpea crop 

 turned under and neither gain nor loss of humus was shown, we have a 

 concrete illustration that the caustic lime burned up the organic matter 

 as fast as it was supplied by the turning in of the crop. Where the 

 cowpea crop was removed for five years, there was a difference in the 

 humus content of the soil of over 5 per cent in favor of the sections 

 which had not been treated with caustic lime. 



In a letter received from the West Virginia Experiment Station we 

 find a discussion of the results of an experiment in the use of caustic 

 lime on soils of that station low in organic matter content. These results 

 show that when these relatively poor soils were treated with complete 

 fertilizer the nitrogen content was increased 728 pounds to the acre dur- 

 ing a fifteen-year period, and that the humus content, during the same 

 time, was increased 14,856 pounds. But when caustic lime was added 

 to the complete fertilizer the nitrogen content was reduced from 728 to 

 213 pounds to the acre, and the humus content from 14,856 to 2,586 

 pounds. When manure alone was used on this land the nitrogen con- 

 tent was increased 1,323 pounds, and the humus content 26,098 to the 

 acre during the fifteen-year period. But when caustic lime was used on 

 the land with the manure the nitrogen content was lowered from 1,323 

 to 870 pounds, and the organic matter content from 26,089 to 19,481 

 pounds. When caustic lime was used alone it lowered the nitrogen 

 content 92 pounds from what it was before the lime was used, and the 

 organic matter content was reduced 3,235 pounds below the normal 

 amount in the soil at the beginning of the experiment. 



In an address before the Legislature of Virginia in January, 1912, 

 Dr. Cyril G. Hopkins stated : "For many years I have searched the 

 records of agricultural history and investigation, and I have not found 

 evidence in favor of using caustic lime in preference to lime carbonate." 



In "Ground Limestone for Southern Soils" Dr. Hopkins says: "The 

 most extended investigations on record relating to the use of ground lime- 

 stone and caustic lime in comparative tests have been conducted by the 

 Pennsylvania Experiment Station. After twenty years results had been 

 secured the Pennsylvania Station reports data showing that the land 

 treated with ground limestone had produced, per acre, during the twenty 



