Earth Study 



847 



Sand. Clay. Loam. 

 The water has nearly reached the upper surface 

 of the sand and is halfway up the loam; in the 

 clay it has climbed but a short distance. 



Experiment j — To show that soil lifts water upfront below — Use the same 



soils arranged in the same way as for Experiment i , but instead of pouring 



water in at the top, place the three lamp chimneys in a pan which has water 



in it about an inch deep. In which 



soil does the water rise most rapidly ? 



In which does it rise the highest? 



After the water has been taken up, 



let the soil stand in the lamp 



chimneys for several days. Which 



soil dries out the soonest? If we 



had three fields, one of loam, one of 



clay, and one of sand, in which 



would the most water be lifted from 



below for the use of the plants? 



Which would retain the water 



longest ? 



Hints for teacher on Experiment j 



• — Water rises through the sand in a 



short time ; if rather fine sand is used 



it requires less than half an hour. 



To rise through loam it will require 



three or four times as long, and may 



not reach the top of the clay for 



several days. If the glass tubes were three or four feet long and allowed 



to stand for several days, we would find that although the water climbs 



very slowly through the clay it will climb to a greater height in clay than 



in loam or sand. Under field 

 conditions clay will retain 

 moisture for a longer time 

 than sand or loam. 



Experiment 4 — To show 

 that mulch keeps the water from 

 evaporating from soils — Take 

 two of the lamp chimneys 

 filled half full with loam. 

 Pour in the same amount of 

 water in each until the soil is 

 thoroughly wet. Cover the 

 top of one with an inch deep 

 of dry, loose earth. Which 

 dries out first? What does 

 the loosening and pulverizing 

 of the soil in our fields by 

 harrowing do for our planted 

 crops ? What is a mulch ? 



Hints for teacher on Experi- 

 ment 4 — The soil covered 

 with a layer of dry soil — 

 a dust mulch — will retain 

 moisture much longer than 

 the unmulched soil. Hence, 

 the farmer or gardener loosens 



111 ni I 1 



The unmulched loam in the chimney at the left 

 dried out in four days. The loam covered With a 

 dust mulch in the other chimney retained moisture 

 for a month. 



