WINTER INJURY TO THE ROOTS 



311 



without snow covering and with snow covering respectively. Under both 

 sets of conditions the clean cultivated land froze deepest. More striking, 

 however, is the different position occupied by the corn plot under different 

 conditions. The reason becomes apparent, however, when the depth of 

 snow covering on the several plots is considered. The close relation 

 between depth of snow and depth of freezing, shown in all plots, is of 

 interest. 



Fig. 31. — Relation of cover crops to depth of snow and depth of frozen soil. 



(After 



Emerson's observations furnish more information: "Early in the 

 winter ... it was noted that soy beans had very few leaves left and 

 that the plants stood perfectly erect, furnishing almost no protection to 

 the soil and that cowpeas, tho they still held their leaves, stood too 

 erect to furnish much protection. The field peas, on the other hand, had 

 held their leaves well and matted down nicely, forming a very good mulch. 

 Corn was also found to have remained very erect as was also the case with 

 cane and millet. Later in winter it was noted that the snow was held 

 very well by corn, cane, millet, soy beans and cowpeas, while field peas 

 and rye, the good covers, laid too flat on the ground to catch the 

 drifting snow. The almost bare stems of such plants as soy beans, which 

 still stood erect, held the snow much better than a plant like field peas 



