94 FARM ARITHMETIC. 



265. How many more tons of water per acre were held 

 in these four feet of soil (dry weight, 80 pounds per 

 cubic foot), by the deeper mulch (cultivated 3 inches), 

 than by the more shallow mulch (cultivated 1 inch) ? 



266. How many more inches of water in the deep- 

 mulched than the shallow-mulched land? 



267. On July 26, 1900, samples of soils were taken 

 from three plats of land on which corn was growing. 

 The observed percentages of moisture content of the soil 

 from these plats were as follows : 



Per cent. 



1. No cultivation weeds allowed to grow, 12.55 



2. Ordinary cultivation some weeds, 18.80 



3. Level cultivation frequent and shallow, 22.64 



How many tons of water per acre on land in corn, 

 where no cultivation was given, and weeds were allowed 

 to grow ? 



268. How many tons where ordinary cultivation was 

 given ? 



269. How many tons where level, shallow, and fre- 

 quent cultivation is given? 



270. What is the percentage of difference, favorable 

 to ordinary cultivation over no cultivation ? 



271. The percentage of difference in favor of level 

 cultivation over no cultivation ? 



Growing crops take water from the soil. Often early 

 spring crops are harvested and the same land is planted 

 in corn or other cultivated crops. Or again a crop of 

 weeds may be permitted to grow on ground to be used 

 later for a cultivated crop. This second crop may suffer 



