CH. xiii] Lime and O^'ganic Matter 221 



when sufficiently finely divided goes further than chalk, 

 which is not usually ground. 



Lime is chemically distinct from limestone or chalk, 

 being the oxide of calcium (CaO). It has certain charac- 

 teristic effects in the soil which neither of the other 

 substances produces. These effects, however, are only 

 transient since the lime is soon converted into carbonate, 

 and ultimately into bicarbonate, through the action of 

 the carbon dioxide always present. 



It dissolves some of the organic compounds in the 

 soil and apparently effects a certain amount of decom- 

 position. This can be demonstrated by mixing 50 grams 

 soil with I to 1 gram of quick lime, adding 200 c.c. of 

 water and shaking weU. An extract tinged with yellow 

 or brown is obtained, which on analysis is found to 

 contain organic matter, potassium, and other substances. 

 Thus addition of excess of lime to the soil may result in 

 excessive decomposition and the loss of valuable plant 

 nutrients. 



"Lime and lime without manure 

 Will make both farm and farmer poor," 



as the old saying goes^. One result of this decomposition 

 apparently is to aid the work of the soil bacteria and to 

 increase the production of plant food. 



^ This was well known on the continent. Heresbach (Rei Rusticae libri 

 quatuor 1594) wrote "Vulgo dici solet, earn rationem stercorandi calce, 

 opulentos parentes, et hberos reddere inopes" which Googe translated 

 "The common people have a speach, that ground enriched with Chalke, 

 makes a rich father, and a beggerly sonne." 



In the Pennsylvania State College experiments, plots annually re- 

 ceiving hme for 25 years contained less nitrogen by 375 lbs. per acre than 

 the plot receiving limestone. In the Virginia experiments the limed plot 

 was found to contain less nitrogen and less organic matter than the un- 

 limed plots. 



