52 



AGRICULTURE. 



[b) Firmly tie over the bottom of each tube a square 

 of clieese-cloth. (Fig. i6) 



{c) Weigh each tube separately, and then record he 

 weights. 



{d) Fill the tubes tliree-fourths f ull of d^r/V^ sand, clay, 

 humus, and loam respectively. 



{e) Carefully weigh each tube with its contents, and 

 record the weights. 



(/) Now fill eacli tube with water which has been 

 leached from stable compost, taking care to record the 

 exact time when the water Jirst comes in contact with tlie 

 soil. 



[g) Support or suspend these tubes in an upright po- 

 sition (Fig. 1 6), and allow the water from each tube 

 to drip into a separate vessel. Observe and record the 

 time required for the water to begin to drip from each 

 tube. Keep 

 each tube filled 

 with the leach- 

 ed water until 

 the soil is satur- 

 ated. Through 

 which tube did 

 the water pass 

 most rapidly ? 

 This passage of 

 water down- 

 ward through 

 the soil is call- 

 ed percola- 

 tion. 



(/;) Compare the color and the odor of the water per- 

 colated. Through which of these soils will soluble 

 plant-food most readily leach ? Which soil will absorb 

 the most plant-food from the water which percolates 

 through it ? 



FIG. l6. APPARATUS FOR EXPERIMENT 5. 



