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7. A pound of rice yields approximately the same amount of energy as a pound of macaroni or a pound of tapioca. Compare the present costs of a pound of each.

8. Compare the cost of a pound of sweet potatoes with 11 pounds of white potatoes. Which is the cheaper if those weights produce nearly equal amounts of energy?

9. The following weights produce approximately equal amounts of energy: 1 pound of potatoes; 3 pounds of tomatoes; 23 pounds of turnips. Which is cheaper at present prices?

10. The following amounts of fruits have approximately equal energy values: 1 pound of raisins; 1 pound of dried figs; 1 pound of dried apricots; 63 pounds of apples; 43 pounds of grapes; 4; pounds of bananas and 8 pounds of oranges. Compare the costs of these fruits as energy producers.

Weigh several oranges to determine the cost per pound. Do the same with bananas if they are sold by the dozen. Most stores now sell bananas by the pound.

11. One pound of cheese is equal to energy value to about 2} pounds of round steak. Which costs the least?

12. Compare the costs of these breakfast foods: 1 pound of oat meal; 1š pounds of corn meal; 18 pounds of wheat breakfast foods. Which is the cheapest if they produce nearly equal amounts of energy?

13. The quantities of cereal breakfast foods, described in problem 12, yield about 1į times as much energy as the weights of fresh fruits described in problem 10. Compare the relative costs of cereals and fruits as energy producers.

14. One pound of crackers produces as much energy as 13 pounds of bread. Which costs less?

15. One pound of peanuts in the shell equal in energy value 13 pounds of English walnuts in the shell. Which is the cheaper?

CHAPTER VI

EFFICIENCY ON THE FARM AND IN THE SCHOOL

In the early days of our country the people were few and land

was plentiful. If one field began to lose its fertility, there was plenty of new land which could be used. Now most of the fertile tracts of land have been

occupied, and over Courtesy International Harvester Co.

100,000,000 people must be fed with the crops from our farms.

It is therefore necessary that we learn how to retain the fertility of our soil and find the most profitable crops and methods of cultivation.

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Exercise 1. The Value of Fertilizers

1. It is estimated that there is produced each year about 150,000,000 tons of barnyard fertilizer worth $200,000,000. What is the estimated value of a ton of this fertilizer?

2. Over $50,000,000 worth of this fertilizer is wasted each year. What per cent is this of the total value of the fertilizer?

Nitrogen is one of the most important food substances needed for growing good crops. Burning straw or cornstalks destroys the nitrogen.

3. The straw from a 25-bushel yield of wheat contains about 15 pounds of nitrogen. If a farmer raises 500 bushels of wheat, how many pounds of nitrogen are contained in the straw?

4. When purchased for fertilizing purposes nitrogen is worth about 20 cents a pound. Find the value of the nitrogen in the straw from the 500-bushel yield of wheat. If this straw is burned, how much loss will the farmer suffer?

5. A 50-bushel yield of corn contains about 25 pounds of nitrogen. How many pounds of nitrogen are contained in the corn crop from a 20-acre field yielding 50 bushels per

acre? 6. If the farmer burns his cornstalks instead of plowing them under, and sells his corn, what is his loss in the fertilizing value of the nitrogen alone from the 20-acre field?

7. One hundred dairy cows weighing 1000 pounds apiece will produce 2,400,000 pounds of fertilizer in a year. How many tons of fertilizer do they produce per year? This fertilizer is worth over $1600. What is the value of the yearly production of fertilizer from a single cow?

Exercise 2. Rotation of Crops At the Illinois Experiment Station an experiment on the value of crop rotation was conducted from 1888 to 1907. On one plot corn was grown every year; on a second plot corn and oats were grown in rotation (corn one year and oats the next); and on the third plot corn, oats, and clover were grown in rotation.

1. The yield on the plot on which corn was grown every year was 29 bushels per acre. What was the income from an acre of this corn if the average price was 40 cents a bushel?

2. The rent on this land and the cost of production were estimated at $10 per acre.

What was the net profit per acre on the first plot?

3. The yield on the second plot, on which corn and oats were grown in rotation, was 48 bushels per acre. What was the income per acre from the corn on the second plot?

4. Estimating the cost of production to be the same, what was the net profit per acre from the corn on the second plot?

5. The yield on the third plot with a rotation of corn, oats and clover was 80 bushels per acre. Find the income at 40 cents per bushel from the corn on this plot. What was the net profit per acre?

Missouri Experiment. Rotation and Fertilizer

6. A similar experiment was conducted at the Missouri Experiment Station. On the plot where corn was grown every year the yield was only 11.8 bushels per acre. What was the income per acre on this land at 40 cents a bushel?

7. The yield on the plot where corn, wheat and clover were grown in rotation was 50.7 bushels per acre. What was the increase in the income per acre due to the crop rotation?

8. On a plot where fertilizer was used in addition to the crop rotation of corn, wheat and clover, there was a yield of 77.6 bushels per acre. Find the value of the increased production due to the use of the fertilizer, counting the corn at 40 cents a bushel.

Pennsylvania Experiment. Rotation and Fertilizer

In Pennsylvania a four-year rotation of corn, oats, wheat and hay was carried on for a period of 24 years on one plot without fertilizer and on another plot with fertilizer.

9. The average profit for the first 12 years on the plot without fertilizer was $10.58 per acre. During the second 12 years the profit was only $7.85 per acre. Find the total income from an acre for the period of 24 years.

10. The average profit for the first 12 years on which the fertilizer was used was $14.07 per acre and for the second 12 years $14.35 per acre. Find the total income from an acre of this plot for the period of 24 years.

11. Find the extra income for the 24 years due to the use of the fertilizer. If 12 tons of fertilizer were applied every 4 years, what was the profit per ton from the use of the fertilizer?

12. What benefit resulted from the use of the fertilizer in addition to the increased yield of the crops?

Exercise 3. Raising Corn

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POOR SEED

In 1918 the production GREATEST CAUSE OF LOW

of corn amounted to 2,582,YIELD OF CORN

814,000 bushels, worth $3,528,313,000. The value of the cotton crop in the same year was $1,616,207,000.

1. How much greater was the value of the corn crop than that of the cotton crop?

2. Corn is generally

planted in hills 32 feet Courtesy International Harvester Co.

apart each way.

How many square feet of ground are given to each hill? (31X 32= ?)

3. There are 43,560 square feet in an acre. Show that there are approximately 3556 hills of corn per acre.

4. If 3 kernels are planted and each kernel grows and produces a stalk, how many stalks are there on an acre of corn?

5. If only one stalk in each hill grows a small ear weighing 8 ounces, what would be the yield per acre? (1 bushel of corn in the ear weighs 70 pounds. See Problem 3 for number of hills per acre.)

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