ORGANIC MATTER 



59 



Exercise IV. — Extraction of partly decomposed organic matter. 



Materials. — Muck, dilute hydrochloric acid, ammonia, hydrate 

 of lime, filter paper and funnel. 



Procedure. — Place about a gram of moist muck on a filter paper 

 in a funnel. Treat the muck with a few drops of dilute hydrochloric 

 acid. Wash out the acid with 50 c.c. of distilled water. Discard 

 this percolation. Now treat the soil with ammonia. After allow- 

 ing it to stand a few minutes wash with distilled water and catch 

 percolate. 



The percolate should be black, showing the presence of partly de- 

 composed organic matter. This is the material seen escaping from 

 manure piles. It is the most valuable portion of the organic matter. 



Treat a portion of this soluble organic matter with hydrate of 

 lime. Note the flocculating effect, which prevents the leaching of 

 organic matter from the soil. 



Exercise V. — Influence of organic matter on rate of percola- 

 tion of water through soils. 



Fig. 12. — Apparatus for studying the influence of the addition of organic 

 matter to a soil on the rate of percolation and percentage of water holding 

 capacity. 



Materials. — Clay or clay loam soil finely pulverized, moist 

 muck, lamp chimneys, torsion balance and weights, cheesecloth. 



Procedure. — Divide the soil in two portions. To one add 10 per- 

 cent of the moist muck. Mix thoroughly. Place equal and definite 



