72 SOILS 



they mostly coarse or fine? If the soil feels dis- 

 tinctly gritty it probably contains a considerable 

 amount of sand; if it feels quite smooth and makes 

 a very smooth, sticky paste when water is added to 



, it, it contains a large percentage of clay or silt. 



* Take a handful of moist not wet soil and 

 squeeze it hard. If the ball of soil crumbles 

 quickly and freely when the pressure is removed 

 the soil contains sufficient humus or sand and is 

 likely to prove of good texture and easy to work. 

 If, however, the ball of moist soil retains its shape 

 to a considerable extent, remaining hard and 

 compact, it indicates that clay and silt predom- 

 inate and that the soil will need to be handled 

 carefully. 



A more accurate test for clay, silt, sand and 

 humus may be made in the following manner. 

 Take a small sample of moist soil, as it is found in 

 the field, say a quart; screen out all except fine par- 

 ticles, and weign it very carefully. Spread it thinly 

 on a pan and set it in a very moderate oven or on the 

 back of the stove, where it will dry slowly, but not 

 burn. When it is perfectly dry weigh it again. 

 The difference shows the amount of water that the 

 soil contains, all of which has been driven off as 

 vapour of water. 



jPlace this dry soil upon a coal-shovel above hot 

 coals, or on a pan placed in a very hot oven. The 

 humus in it will begin to smoke. If the soil is 

 kept very hot for two or three hours practically all 

 of the humus will burn, leaving only the "ash" 

 or mineral part of the soil. A fairly reliable meas- 

 ure of the amount of humus that the soil contains is 

 secured by comparing the weights before and after 

 burning. All soils that have a fair proportion of 

 humus and are therefore most valuable for farming, 



