176 SOILS 



Rolling May Warm the Soil. Rolling has a 

 marked effect upon the temperature of the soil. 

 It makes it warmer if the weather is clear and 

 warm, but colder if the weather is cloudy and cold. 

 King recorded an average difference of nearly three 

 degrees between the rolled and the unrolled soil 

 of the same field at a depth of three inches, the 

 rolled soil being warmer. The soil becomes 

 colder during cold weather, tnd warmer during 

 warm weather than if it were [rolled, since on the 

 unrolled field there is more surface exposed to the 

 air. The more firmly a soil is packed on the sur- 

 face the better does it conduct heat; so that during 

 the night and during cold rainy weather the rolled 

 land is colder at the surface than the unrolled land. 



Incidental Benefits of Rolling. Incidental bene- 

 fits of rolling in some cases are that it puts the soil 

 into such a condition that other tools can handle 

 it more effectively; it leaves the surface in better 

 shape for marking; it smooths the soil so that 

 small seeds may be distributed over it more evenly. 

 Fall-sown grass, clover and grain are often rolled 

 in very early spring to lessen the likelihood of 

 injury from heaving by freezing and thawing and 

 to make the surface smoother for mowing. These, 

 however, are insignificant as compared with rolling 

 for moisture and for crushing lumps. 



From the foregoing statements it is evident that 

 rolling may be beneficial or detrimental, according 

 to the soil and the season; it is a practice that 

 must be used with discretion. In general, it 

 may be said that rolling accomplishes two very 

 useful purposes; it increases the water-holding 

 capacity of light soils and aids the germination of 

 seeds in them; and it crushes the lumps of cloddy 

 soils. The tendency is to restrict the use of the 



