farmers' institutes. 247 



the use of cover crops. 



Cover crops may be used to prevent waste of fertility. Nitrates will 

 leach out of a soil if not used by plants soon after they are formed. It 

 has been shown at the Minnesota Experiment Station that in eight years 

 of continuous cropping to wheat fully eight times as much nitrogen was 

 lost from the soil as was removed by the wheat. It must have been 

 leached out during the warm summer months when nitrification was most 

 active, but after the wheat crop had matured. Cover crops will take up 

 nitrates and thus prevent their loss by leaching. 



IMPROVEMENT BY ROTATION OF CROPS. 



Crops vary in their demands upon the soil, some removing much 

 more fertility than others. They also vary in their feeding habits, some 

 removing large quantities of one element while others remove large quan- 

 tities of another element. These differences are especially well marked 

 when considering equal quantities of the crops, but are not so marked 

 when we compare the maximum yields of the various crops. Still even 

 then there are differences and we may often prevent a particularly heavy 

 drain upon one element by introducing a crop that removes less of that 

 element and more of another. The advantage to be gained in this way is 

 not so great, however, as it is commonly believed to be. Plants van,' in 

 their ability to feed upon the soil and often a great advantage can be 

 gained by introducing a plant in the rotation which can extract plant food 

 from soil upon which another plant might not be able to feed. By far 

 the greatest advantage in rotation of crops consists in the opportunity it 

 affords of growing leguminous plants upon all the cultivated portion of 

 the farm. All farm crops with the exception of the legumes are extreme- 

 ly hard on the nitrogen of the soil when maximum yields aie considered 

 and so any system of farming which rests the soil with respect to nitrogen 

 will prolong the producing power of the soil. When a part of the farm is 

 used for pasture it is of great advantage to rotate the pasture land from one 

 field to another. Very little fertility is removed from pasture land, the 

 animals returning to the soil nearly all the fertility required to produce 

 the grass upon which they feed, so the land is given a rest by putting it 

 in pasture. 



IMPROVING SOIL BY CHANGE OF BUSINESS. 



If we follow the history of the development of new soils in the United 

 States we will find that at first they have been devoted to grain raising 

 for the markets, but that this system of farming gradually gives way to 

 one in which stock raising predominates. A moment's consideration of 



