I3O SOILS 



at that time of the year, when the soil is most nearly 

 exhausted of its nitrate stores. 



Observe how nature does : when lands have produced 

 their harvests, they are low in nitrates so nature brings 

 in cold and frost and death. Organic matter is sent back 

 to the soil from whence it came ; and while winter storms 

 and blows, and later passes into the warmer circle of 

 spring, denitrification is not unlikely taking place, where 

 no call is made for nitrates, for few plants are needing 

 them. Consequently, when the time comes, when greater 

 stores are necessary, the organic matter has been de- 

 stroyed, leaving denitrifying bacteria largely inactive, and 

 careless, and at the same time unmindful of the accumu- 

 lation of nitrates by the nitrifying bacteria, now busy 

 at work, and concentrating every effort to secure a maxi- 

 mum quantity of every fruiting plant. 



What these facts teach. A knowledge of the way in 

 which these many kinds of bacteria work ought to help 

 in lessening nitrogen loss, in stimulating nitrifying bac- 

 teria into activity, and in increasing the yields of crops. In 

 the first place, it is a mistake to incorporate raw organic 

 matter with the soil, when the nitrate stores are already 

 there in considerable quantities. It is also a mistake to 

 apply organic matter some time previously to land where 

 crops soon must fructify, for the reason that denitrifying 

 bacteria may use more of the nitrate compounds than the 

 growing crop itself. It is far better, in the light of these 

 important soil findings, to apply organic matter during 

 the fall or winter or early spring, when the stores of 

 nitrates are at their lowest points. This, then, is the time 

 when manure should go to the fields, when denitrifica- 

 tion can take place without affecting the available nitro- 

 gen supplies of the soil. 



We know, also, that the nitrobacteria the kind that 



