106 AGRICULTURE 



up nitrogen and leaves plant food in the surface soil. It is there- 

 fore valuable to precede a weak-feeding plant, such as wheat. 

 Tobacco is another good crop to precede wheat. It is a tap- 

 rooted plant and it leaves the soil in a good condition for the 

 fibrous-rooted cereal. 



Fifth: Crops should rotate so as to keep in check weeds and 

 insect pests and fungous diseases. Certain weeds and insects 

 flourish on certain crops. Moreover, plants grown a long period 

 on the same soil lose vigor and ability to resist their enemies. 

 These enemies are checked or destroyed by rotation of crops. 

 Sometimes it is necessary to plan or change a rotation so as to 

 reclaim land from these pests. Farmers change their crops and 

 their methods of cultivation to check wilt diseases and weevils. By 

 rotation of crops, lands can be freed of cattle ticks, so injurious 

 to stock in the South. 



Sixth: Crops should rotate so as to furnish abundance of 

 food for all live stock kept on the farm. When the farmer buys 

 feed, he has to pay not only the cost of production, but the 

 producer's profit and the cost of marketing and transportation. 



Seventh: Crops should rotate so as to keep land occupied. 

 If a market or food crop is not being grown, there should be 

 a catch, or cover, crop on the land. This will save and increase 

 plant food, supply humus, and prevent the washing and leach- 

 ing which cause far more loss of fertility than does cropping. 

 Sandy soils and rolling land should never be left bare in winter. 

 It is better for the farmer and the farm for them to be kept busy 

 producing fertility to feed the next season's crops. 



Eighth: Crops should rotate so as to secure for men and teams 

 as even distribution of labor as possible. Where this is not done, 

 labor is more expensive and more unsatisfactory. In the great 

 wheat region of the West, work is constant and hard for two 



