MANUAL FOR SUGAR GROWERS. 27 



ammonia salts fulfil this condition. 2. Air; and 

 this is one of the reasons why tillage and working 

 the soil increases the fertility, as it leads to more 

 rapid nitrification. 3. Moisture. 4. A tempera- 

 ture of from 40° F. to 110° F., nitrification being 

 most active at a temperature of about ordinary 

 summer heat. From this it will be seen that the 

 natural condition of affairs in the tropics — high 

 temperature with abundant moisture — is conducive 

 to rapid nitrification. 5. It is necessary that some 

 base be present in the soil, i.e., some substance capa- 

 ble of neutralising acids ; in almost every case this 

 condition is fulfilled by the presence of carbonate of 

 lime or chalk, and this is one of the reasons why 

 this substance is so important as a constituent of 

 soils. It is very evident, then, that many of the 

 points which were regarded as of importance in 

 connection with condition or heart are those which 

 are favourable to nitrification ; and thus the theory 

 of nitrification supplies us with a reason for per- 

 forming many agricultural operations which previ- 

 ously rested only on a basis of tradition of success- 

 ful practice. 



The author has seen certain West Indian soils 

 exceptionally rich in nitrogen, yet containing barely 

 a trace of nitrate, owing to the non-fulfilment of 

 some of the conditions given above, and this chiefly 

 due to defective tillage and to the trampling of cat- 

 tle on wet lands. In one instance a sample of soil 

 which, when taken from the field, contained nitrate 

 equal to only six pounds per million, after being kept 

 in the laboratory for twenty-eight days, contained 



