3l8 SOILS AND FERTILIZERS 



Experiment No. u 

 Deportment of Soils when Wet 



Place about 5 gms. of the soil used in Experiment No. 9 in the 

 palm of the hand. Wet and knead. Note whether a plastic mass 

 is formed. If the soil is sticky, it indicates the presence of plastic 

 clay. Rub some of the soil between thumb and finger ; if it is com- 

 posed largely of clay, it will feel smooth and oily. The sand parti- 

 cles impart a sharp gritty feeling ; in the presence of clay this is more 

 or less modified. Note whether the lumps of dry soil crush easily. 

 The way a soil responds when crushed, wet, and kneaded, gives 

 some idea of its tillage properties. 



Experiment No. 12 

 Rate of Movement of Water through Soils 



Weigh a soil tube and fill it to within two inches of the top with 

 sand. Weigh again. In like manner weigh and fill two other 

 tubes, one with clay and one with loam. Support the tubes from 

 the ring stand as noted in Fig. No. 58. Place a receptacle under 

 the outlet of each tube. Measure into cylinders or large beakers 

 three 500 cc. portions of water. From one of these beakers slowly 

 pour the water into the sand cylinder, and note the length of time 

 required for the water to percolate through the sand, and the amount 

 of water that percolates in a given time. Replenish the water in 

 the beaker with measured amounts as needed. In like manner test 

 the clay and the loam. After the water has ceased dripping from 

 the tubes, weigh and calculate the amount retained by the soils. 



Experiment No. 13 

 Properties of Rocks from which Many Soils are Derived 



Study the laboratory samples of rocks and fill out the following 

 table : 



