SEEDS AND SEEDING 91 



The disadvantages of a nurse crop, as far as the grass 

 is concerned, are : 



1. Weakening the grass by shading. 



2. Injuring the young grass when soil moisture is not 

 sufficient for both. 



3. Requiring a higher rate of seeding of the grass. 

 Wheat, rye, barley and oats are desirable as nurse 



crops, probably in the order named, but there are few 

 comparative experimental data available. Oats shade 

 the ground more than barley, and barley more than wheat 

 or rye. The time of harvesting the nurse crop is also of 

 some importance to the grass crop, as sudden exposure 

 of the latter to heat and drought is very harmful. The 

 water requirement of each of the four nurse crops is least 

 for wheat, followed in order by barley, oats and rye. 



