THE SEED BED 47 



below can more readily move up into the seed bed. But 

 since more soil moisture can thus reach the surface 

 and then evaporate, the roller should be followed by 

 the harrow to form a shallow mulch. If the weather 

 has been wet and cold, and there is much moisture in 

 the plowed soil, the roller will pack it down, and cause 

 it to lose some of its moisture by evaporation. Some- 



HARROW 



times rolling the land helps the soil to warm up earlier 

 in the spring. 



Special seed beds. -- Tobacco and some other plants 

 have such tiny seeds it is difficult to make a proper 

 seed bed in the field, so they are started in special 

 seed beds; and the plants are afterward moved to 

 the field. Tomatoes, cabbage, and celery require a 

 long season in which to grow, and the seeds are first 

 started in a hotbed or in a greenhouse. A hotbed 

 is a seed bed having some arrangement for warming the 

 soil from underneath, so the plants may be started 



