CLIMATE. 375 



humid region; more water is required in a warm than in a cold 

 region. Winds are also a determining factor. 



PROBLEMS. 



1. Observations made in Illinois showed that in one week in July, 

 the growth of corn amounted to 1,300 pounds of dry matter per acre; if 

 the water required to produce 1 pound of dry matter was determined to 

 be 233 pounds, that amount of water was equivalent to how many inches 

 of rainfall? 



2. In an experiment in Wisconsin it was determined that the 

 amount of water necessary to produce each pound of dry matter in corn 

 was 272 pounds per acre in a certain experiment; this was equivalent to 

 how many inches rainfall? 



3. If in producing a ton of clover hay, which is 85 per cent dry 

 matter, 470 pounds of water were required to produce each pound of 

 dry matter, how many inches of rainfall would be required to furnish 

 sufficient water to produce two tons of clover hay per acre? 



4. Assuming that the average production of dry matter in the 

 crops of the average farm is two tons per acre, what is the amount of 

 water in pounds required to produce a yield of one pound of dry matter, 

 if the total amount required to produce two tons of dry matter is 

 equivalent to a rainfall of 15 inches? 



5. It has been observed that a single corn plant during the first 

 week of August, when it was coming into tassel and when the ear was 

 forming, used water at the rate of one and one-half quarts per day. 

 At that rate how much would that plant use in two weeks? 



6. It was estimated that the amount of water that fell during the 

 few days that produced the great floods in Ohio, in March, 1913, was 

 on an average equal to about 10 inches of rainfall; if the area of Ohio 

 is 43,000 sq. mi. how large a cube of water would represent this amount 

 of rainfall? 



7. How large a lake would the Ohio flood rains of March 1913, 

 have filled to an average depth of 50 feet, if the length of the lake is to 

 the width as 3 is to 5? 



The principles upon which dry farming are dependent for 

 success are as follows: 



1 . Deep plowing and pulverizing to absorb all the moisture from 

 rain and snow. 



2. Compacting subsoil to enable water to rise to the roots of 

 growing crops. 



3. Stirring upper few inches of soil to act as a mulch or blanket 

 to prevent moisture evaporation. 



