1. 1,. i MIN01 - CROPS. 



533 



and that the removal of the aboveground portion of the plan.1 from the land 



i ii ;in- the removal >f a large amount of mtrogen. An increase in the 

 nitrogen content of the -oil can only result from the growing of Leguminous 

 crops when they arc fed off, ploughed in. or soiled to stock, ami the resultant 



manure from tin- -took returned to the -oil. 



Soil Inoculation. 



The soil condition.- that in general favour nitrification also favour the 

 presence of nitrogen-fixing bacteria in association with legumes, and conse- 

 quently the number and development of the nodule?. Ill-drained, acid soils, 

 deficient in organic matter, tend to weaken or destroy the bacteria, and it 

 is probable that this in pan explains the failure of leguminous crops under 

 suoh conditions. The introduction of cultures of bacteria into the soil has 

 been attended with considerable success in some parts of America, and has 



Bacterial Nodules (natural size) on roots of Tares at Hawkeibury Agricultural 

 College Orchard. 



been much advertised as a method of promoting fertility, especially where 

 the growth of legumes is proposed. In some parts of the United States, in 

 fact, use of such cultures appears to be advisable — even necessary. In New 

 South Wales, however, experiments with culture.- have revealed no advantage 

 from their use, the soil and atmospheric conditions apparently favouring 

 nitrification in a natural way. 



In localities where lucerne has not been grown before, it may be necessary 



Tjefore sowing to inoculate the seed with nodule bacteria in order that the 



'■ts may attain a healthy and vigorous condition. The best way of 



