THE CORN CROP IN THE UNITED STATES. 103 



per acre. What was the per cent, gain of the best variety over the 

 poorest yielding variety? 



3. In Putnam County, O., a number of farmers planted 16 varieties of 

 corn; soil, care and cultivation was uniform. The following dif- 

 ference, therefore, came from the kind of seed planted: Highest yield 

 96 bushels and lowest yield 75 bushels per acre. What was the loss 

 per cent, in planting the poorer seed instead of planting the seed 

 giving highest yield? 



4. In a variety test conducted in Indiana to determine the kind of corn 

 best suited to the soil and climatic conditions, resulted in a difference 

 of 40 bushels per acre; 108 bushels was the highest, and 68 bushels 

 was the lowest yield per acre. What was the loss of the farmer who 

 had land capable of producing the highest yield, if he planted the 

 variety giving the lowest yield on a field of 7 acres, if the price of 

 corn was 40c a bushel? 



5. If a farmer raising 70 bushels of corn per acre has increased 

 his production 25 per cent by careful selection of variety, what was 

 his yield per acre before making the selection? 



PROBLEMS. 



1. At the Ohio Experiment Station, tests conducted with 5 different 

 varieties of corn for a period extending over 5 years, showed that seed 

 ears ranging in length from 9 to 10.5 inches yielded about 4 bushels more 

 per acre than seed ears ranging in length from 6.5 to 8.2 inches in length ; 

 what was the gain in profit in planting a field of 10 acres with the larger 

 ears if the corn was sold at 43c per bushel? 



2. It has been demonstrated by both the Ohio and the Nebraska 

 Experiment Stations that smoother types of kernels outyielded the 

 rougher types. The smooth types on 100 tenth acre plots outyielded the 

 rough types by 2.42 bushels per acre ; if the production was 70 bushels 

 per acre, what was the gain per cent, by planting smoother kernels? 



*3. In an experiment it was determined that ears with filled tips 

 produced 3 per cent, more per acre in a four-year test than ears with 

 poor tips ; what was the gain in bushels of the farmer using the ears with 

 filled tips in planting 32 acres of corn that yielded 75 bushels per acre? 



4. It has been shown by tests carried on under supervision of the 

 U. S. Government in a number of states that field selected ears produced 

 16 bushels more per acre or 20 per cent, more than crib-selected ears. 

 What was the number of bushels produced per acre by planting field 

 selected ears? 



5. Seed ears selected from high yielding rows in an ear-to-row 

 breeding plat produced 18 bushels per acre or 16 per cent, more than field 

 selected ears from a field of the same kind of corn. What would be the 

 gain in bushels by using seed from high yielding ears selected from a 

 breeding plat to plant 20 acres giving same results as above stated? 



* Continual selection of ears with filled tips will eventually result 

 in shortening the ear of corn. 



