216 GARDEN PROFITS 



tions of carbon and nitrogen, of which manures, 

 humus and other animal and vegetable wastes 

 are composed. This oxidizing change results in 

 new combinations, of nitrogen and a maximum 

 proportion of oxygen, which are directly assimilable 

 by plants. 



The second group, of "nitrogen fixers," possesses 

 the power to act on gaseous, atmospheric nitrogen, 

 and with it to build up the compounds which mark 

 the beginning of the nitrification process outlined 

 above. These latter organisms are themselves of 

 two kinds: first, those which have entered into 

 partnership with certain plants the legumes, 

 such as beans, peas, etc., in which they store up 

 the plant food, the accumulations forming nodules 

 or tubercles on the roots of those plants; and 

 second, those which accomplish the same results, 

 but without the assistance or cooperation of growing 

 plants. You will probably by this time have real- 

 ized why the growth of leguminous "cover crops" 

 is of such benefit to the soil. 



THE GREATEST SECRET OF ALL 



Now the grandest part of all this is, that this 

 work and all these changes are going on in the soil 

 all the time. Plant food is being prepared at all 

 hours of the day and night, and there is enough 

 raw material on hand to last for many a year. The 

 only way you can possibly stop the great work of the 

 bacteria is by shutting off their air supply, by drown- 

 ing them or by poisoning them with acids just as 



