EXERCISE 36 



FACTORS DETERMINING THE YIELD OF CORN 



Statement. The average corn yield of the United States is about 24 bushels an acre, while the 

 best farmers secure from 70 to 100 bushels. As many as 228I bushels have been produced by a Corn 



Club boy in South Carolina. Is the reason for 

 the low average yield the small size of the ears 

 produced, or the small number of ears, or both ? 



Object. To determine the cause for the wide 

 variation in the acre production of corn. 



Materials. Scales; tape measure; ears of corn 

 of average size. An ear weighing six ounces and 

 one weighing approximately 2\ ounces. 



Directions. 1 . Have each student secure an ear 

 of corn of approximately the average size for the 

 locality. Ascertain the weight, length, and circum- 

 ference of these average ears and compare the 

 results with the standard for your section of the 

 state as determined by the score card of your 

 Agricultural College or Corn Growers' Association. 



2. When corn is planted in hills 3§ feet apart 

 each way, there are 3556 hills on an acre. 



3. Compute the yield of corn per acre with three 

 stalks to the hill, a perfect stand, and each stalk 

 bearing an ear, assuming that each ear weighed the 

 same as the average of the ears brought in by the 

 students. How does this yield compare with the 

 actual yield of the neighborhood? 



4. Compute the yield, assuming that the ears weigh 6 ounces each. How does this yield compare 

 with the local yield ? Secure a 6-ounce ear. How does it compare with the average ear brought in 

 by the students? 



5. Compute the yield on the basis of a 2 J-ounce ear to each stalk. Compare this yield with the local 

 yield and with the average yield of the United States. Compare a 2§-ounce ear with the ears brought in 

 by the students. 



6. Assuming that the students have brought in ears of average size for the neighborhood and 

 assuming the average yield for the United States to be 24 bushels an acre, what proportion of the 

 stalks have ears on the basis of a perfect stand of three stalks to the hill ? What proportion have 

 ears on the basis of two stalks to the hill and a perfect stand ? 



Questions. Is the low yield of the neighborhood due to the small size of the ears or to the small num- 

 ber of ears produced per acre ? Is the small number of ears produced due to the imperfections of stand or 

 to the large number of barren stalks, or both ? How in your judgment may the corn yield be most 

 readily increased? 



References. Waters, H. J. Essentials of Agriculture, p. 135. Ginn and Company. Dtjggar, J. F. 

 Southern Field Crops, pp. 114-119. The Macmillan Company. Morgan, J. O. Field Crops for the Cotton 

 Belt, pp. 243-244. The Macmillan Company. Montgomery, E. G. The Corn Crops, pp. 57-58, 122-123. 

 The Macmillan Company. 



[72] 



Fig. 44. Comparative weights of ears of com 



a, 12 ounces; b, 6 ounces; c, 2j ounces. Which of these ears of corn 



represents the size of ear produced in the neighborhood ? Is the small 



size of ear the principal cause of low yields? 



