260 SOILS AND PLANT LIFE 



By taking some of the soil found in such a field at a 

 depth of from two to six inches and scattering it uniformly 

 at the rate of about three hundred pounds per acre over 

 another field in which we wish to raise the same crop, we 

 may easily introduce the bacteria needed by the clover 

 that we expect to grow. 



Since these bacteria die quickly when exposed to direct 

 sunhght, it is necessary to scatter the soil containing them 

 on a cloudy day or in the evening, and it should be har- 

 rowed or disced in immediately. 



This inoculation is not necessary as a rule in growing 

 certain clovers because the particular bacteria needed 

 are already in the soil. However, in the case of alfalfa 

 east of the Missouri River, it is very frequently a matter 

 of the utmost importance. 



199. The most Suitable Nurse Crops for Clovers. — 

 As was shown in Section 192, oats are not a suitable nurse 

 crop for clovers. 



Winter wheat and rye are perhaps the most desirable 

 small grain crops to use for this purpose since they do 

 not wholly exclude the sunlight and are removed from the 

 ground early in the season. Spring wheat and barley 

 are more objectionable, but these crops are still to be 

 preferred to oats. 



The rate of seeding of the nurse crop should not be in any 

 case more than two thirds of what it would be if the 

 clover were not sown ; and it is better yet if only a half 

 the usual amount of seed is used, as the thinner stand will 

 admit more sunhght to the young clover plants. 



If it is found necessary to use oats as a nurse crop, the 

 stand should not only be very thin, but the oats should 

 be cut for hay as soon as the kernels are in the milk 

 stage. 



