Grade. 

 Date. . 



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EXERCISE 29 



Absorption of Plant Food by Soils 

 Purpose. — To show the power of soils to absorb solu})le food materials and 

 humus and the influence of lime on this process. 



Place six glass or metal percolators in the rack in their proper order. Fold 

 small pieces of filter paper to be carefully inserted in the base of each 

 percolator. 

 Fill the percolators with soil as follows: 

 No 1. 400 grams of clay loam. 

 No. 2. 400 grams of clay loam. 

 No. 3. 400 grams of clay loam with which there has been mixed 5 



grams of lime. 

 No. 4. 400 grams of sandy loam. 

 No. 5. 400 grams of sandy loam. 



No. 6. 400 grams sandy loam with which there has been thoroughly 

 mixed 5 grams of lime. 

 Add the following solutions to the designated portions of soil: 

 Funnels Nos. 1, 3, 4 and 6 — 300 cc. of manure extract. 

 Funnels Nos. 2 and 5 — 300 cc. of potassium permanganate solution. 

 Note carefully the rate of passage of the liquid through different portions 

 of the soil. Collect and examine the first five cc. of solution that passes 

 through the stem of each funnel, comparing its color with subsequent 

 portions of the original liquid, and the different treatments one with 



Ahsorption of Plant Food by Soils 



"Adapted from Department of Soil Technology, Cornell University. 



