PREPARATION AND PLANTING 163 



TIME OF PLOWING 



113. When land is fall-plowed it is exposed more com- 

 pletely to the action of frost, thus giving a finer state of 

 pulverization. This is often an advantage with heavy 

 soils, but in light soils it may actually be a disadvantage. 

 Also, when a cover crop is to be turned under, there is 

 more time for decomposition when turned under in the fall. 



When the soil is infested with the larvae of injurious 

 insects, fall plowing just as freezing weather begins will 

 often destroy many of these. For early planted crops 

 there is not always enough time for proper preparation of 

 all the land in the spring, and it is good farm management 

 to do part of the plowing in the fall. 



Early spring plowing for corn, compared with late 

 spring plowing, has not been the subject of extensive 

 investigation. An experiment carried for a single season 

 by Quiroga,^ at the Ohio State University, showed an 

 increase of about 7 per cent in the crop with early 

 spring plowing overlate, and a marked increase in avail- 

 able nitrogen was found in the early plowed land through- 

 out the season. 



DEPTH OF PLOWING 



114. From experiment stations some twenty-six tests 

 have been reported on deep and shallow plowing for corn. 

 These results cannot be regarded as very significant as a 

 guide in specific cases, since the results were obtained 

 under a great variety of conditions. They may be sum- 

 marized as follows : — 



Favorable to deep plowing 14 



Favorable to shallow plowing 6 



Indifferent results 6 



1 QuiKOGA. Ohio State Univ. Bui., Series 8, No. 28. 



