Dec. 2 4 ,1917 Decomposition of Green and Stable Manures in Soil 681 
of the organic matter or whether it is simply due to a gradual liberation 
of the carbon dioxid of the calcium carbonate by relatively insoluble 
acids or by acids being gradually formed from organic matter. 
Figure 2 shows the curves for the soils treated with oats alone and in 
the combinations with manure and lime. The noteworthy thing here 
is the slow initial rate of decomposition of the green manure and then its 
rapid decomposition followed by a slowing up of the process. Antici¬ 
pating the results of the experiment which follows, we may say that 
probably the slow action at first was due to the dry condition of the oats. 
The slowing up of the process is due, no doubt, simply to the relative 
exhaustion of the more easily decomposed material in the added green 
manure. 
3 /O /3 PO PS " 30 3 S *?0 43 
Fig. 2.—Graphs of the quantity of carbon evolved as carbon dioxid in soils treated with oats alone and in 
combination with manure and lime. 
The curves for the green clover in its various combinations are shown 
in figure 3. In general th& same may be said of these curves as of those 
for the oats. However, the clover decomposed much more rapidly than 
the oats in the early periods. 
In Table III the summarized data for the whole experiment are given. 
An explanation of some of the columns of the table besides that appear¬ 
ing at the column head will probably make the table clearer. Unless 
otherwise indicated, all results are expressed in terms of pounds of carbon 
per acre of 2,000,000 pounds of soil. The figures in the second column 
were obtained from the analyses of the respective manure for total carbon. 
The values in the third column were found from the pounds of carbon 
in the soil originally and the added carbon. A sample of the air-dried 
calcium carbonate used was analyzed for carbon dioxid. From the 
amount obtained it was computed that the calcium carbonate was 94.42 
