Knv i r : 7 



water supported the larger microbial activity, as measured by carbon 

 dioxide production. One cannot say that moisture tension is the sin";le 

 factor that limits microbiological activity. 



In the same Table the data are grouped showing equal moisture contents 

 but in different plant materials. Consider the data for Alfalfa and Oat 

 Straw. Each was 2U^ moisture content. Alfalfa was at about ?jh% R.H. 

 and the Oat Straw at about Q9% R.H. The greater microbiological activity 

 was found in the Alfalfa. Thus, one cannot say that moisture content 

 alone is involved; there is a difference in the kind of plant materials 

 too. So it may be that there are other things besides moisture involved. 



Table i;. Threshold Moisture Conditions Indicated 



Table h illustrates again that it is difficult to say that overall 

 microbiological activity is a function of total moisture. There seems 

 to be a combination of the tenacity with which moisture is held to 

 particle siirfaces and the total moisture. Both factors are needed to 

 explain limiting moisture conditions for microbes. 



Table 5 presents data relating microbial activity to moisture tension. 

 As the moisture present x^as decreased, the numbers of all the organisms 

 increased. Now we want to know whether or not overall microbiological 

 activity is a straight function of moisture content or whether there was 

 seme temperature interaction. 



In Table 6 we have some data which illustrate that, as far as these 

 studies were concerned, it seemed that each factor operated fairly 

 independently, and we did not find any interaction between the two. 

 That is, as vie increased the temperature between certain limits, there 

 resulted an increase in activity regardless of the moisture content. 

 Increased moisture content resulted in increased activity regardless 

 of temperature, and there was no interaction. I suspect in some cases 

 one would find an interaction. 



