HOW ROTATIONS HELP OUT IJ 



The best rotation demands, not only a change m 

 crops, but a change in the feeding habits of the crop. 

 For instance, plants that are shallow feeders should 

 follow those whose roots penetrate the ground 

 deeply. Corn, a shallow penetrator, should follow 

 clover or alfalfa, a deep grower. As the clover 

 roots strike deeply, the tightly bound subsoil is 

 opened, moisture goes down, air enters, and roots 

 decay — all contributing to the making and releasing 

 of plant food from the compounds that hold it. 



VARYING NEEDS OF PLANTS 



Then, again, plants vary as .o taste. Some, like 

 potatoes, fancy potassium in abundance. Corn 

 does best when the soil has an abundance of nitro- 

 gen, and all grain crops must have some potash and 

 phosphorus to make well-filled heads. 



Crop rotation permits each of these to find its 

 favorite dish. Clover, for instance, gets its nitro- 

 gen from the air, and also draws up from the sub- 

 soil mineral elements, and even gets out of the way 

 before a summer crop comes on. Suppose, then, we 

 follow clover by com. Nitrogen, which has been 

 desired by the corn, has been stored away in the 

 soil by the clover. The clover stubble and roots 

 which are plowed under furnish vegetable matter 

 for further feeding; the soil is made loose and 

 mellow, and hence moisture is held in greater 

 abundance, so the plant suffers less severely should 

 a dry, hot summer come on. After corn can come 

 a crop like wheat or rye or crimson clover to make a 

 cover crop to prevent the washing of land or the 

 leaching of valuable plant food during the winter's 

 rain and snow. 



