FALL PLOWING 



147 



hshed so readily with deep |)lo\viiig as wlicii the plmving is shallow. 

 Plowing- breaks up the capillary connection with the sub-soil, 

 which must in turn be re-established or A'igorous plant growth is im- 

 possible. Deep spring plowing and spring sub-soiling arc likely to 

 result in diminished crops, cspiccially if done after the spring rams. 

 The loosening of the soil to great depths admits air and facilitates 

 the loss of soil moisture. It also interrupts capillarity so that the 

 moisture is not readily drawn from greater depths. 



DIAaEAM SHOWING THE EFFECT OF THE MOLD BOARD UPON 



THE CAPILLARY TUBES IN THE SOIL. 

 The layers of soil by gliding over each other break off the tubes. The. 



more abrupt the mold board the greater the amount of crumbling of 



tlte furrow-slice. 



Fall Plowing. Fall plowing is not considered advisable in the 

 south, where the winters arc Aery mild, accompanied with little or no 

 cold weather. In Illinois, Iowa, Minnesota and Nebraska, the temper- 

 ature becomes low and the weather is so variable as to cause con- 

 siderable heaving of the surface. Freezing disintegrates the soil, 

 and the mellowing" of the furrow slice allows the nitrifying bacteria 

 to begin action early in the spring. Weedy areas are plowed in the 

 fall to check the growth and bury the immature seeds. In fact, many 

 consider this the only object of fall plowing. Wherever a crop, 

 whether a crop of weeds or of fall forage, grows late in the fall, the 

 following corn crop is slow in starting. That is, the available plant 

 food was drawn upon until cold weather set in, thus not allowing the 

 formation of soluble compounds during the warm weather of the 

 autumn months. In the rougher corn sections, fall plowed fields 

 wash so badly and ditches form so quickly that the practice should 

 be discontinued. This is especially true of soils which have been 

 depleted of their humus. There being no organic matter present to 

 retLin the moisture and hold the particles of soil, the whole mass 



