EXERCISE 40 



CORN CULTIVATION 



Statement. Some crops, such as the pasture grasses, are grown successfully without cultivating 

 the soil in which they are growing. Other crops, such as wheat and oats, need only the tillage required 

 properly to prepare the seed bed. A large number of important crops, like corn, cotton, fruits, and 

 garden vegetables, must have the soil about them tilled several times during their growing period if 

 satisfactory results are to be obtained. 



Object. To understand the purposes and proper methods of cultivating corn. 



Materials. Kernels of corn; three large boxes at least two feet square and one foot deep, with 

 holes in the bottom to provide drainage, and filled with finely screened garden soil. 



Directions. Label the boxes i, 2, and 3, respectively, and in each plant three kernels of corn. Wet 

 the soil in each box, using the same amount of water for each. As soon as the soil is dry enough to 

 work stir the surface in box 1 to a depth of one-half inch and leave the others untreated. Observe 

 whether this makes any difference in the time required for the plants to get above ground. Explain. 



Fig. 49. The effect of cultivation on the growth of corn 

 The field at the left was plowed, harrowed, and cultivated three times; yield 40 bushels an acre. The field at the right was plowed and 

 harrowed, but not cultivated ; the weeds so completely choked the corn that the yield' was less than half a bushel to the acre. (Courtesy 



Illinois Experiment Station) 



After the corn is up and growing well, remove all but one healthy plant from each box. Give each 

 box the same amount of water. Every ten days after the plants are up cultivate the soil in boxes i 

 and 2 . Cultivate box i three inches deep the first time, two inches deep the second and third times, 

 and one inch deep the last. Cultivate box 2 four inches deep each time. In cultivating do not stir 

 the soil within two inches of the plant. Leave box 3 undisturbed, allowing the weeds to grow. Toward 

 the end of the experiment cease watering the plants and allow them to suffer for. moisture as corn 

 plants do in a drought. Compare the growth of the plants as long as it is possible to continue the ex- 

 periment and note under which treatment the plants best withstood the effects of the drought. 



Study the root system of the plants in each box and note where the roots are located and if any 

 roots were destroyed by any system of tillage. Remove the weeds in box 3 at the surface. Weigh 

 them and compare this weight with that of the corn stalks cut off at the surface. Compute the pro- 

 portion of moisture used in corn growth and weed growth respectively. 



Questions. What are the principal benefits of cultivation of corn ? In what ways do weeds hinder 

 the growth of the corn plants ? When and how may weeds be most easily and completely destroyed ? 



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