114 SCHOOL AND HOME GARDENING 



mouthed can. Place it on a stove or lieater where it will dry rapidly 

 l>ut not burn. The soil may be turned over or stirred carefully in a 

 few hours. After a day or more it should be weighed again after 

 cooling, and the loss in weight determined. This loss is due to 

 evaporation of the capillary water. 



Some soils naturally hold much more water than others. 

 The character of the soil and its value for certain crops may 

 be partly determined by testing for moisture. 



3. Testing for Organic Matter. — Weigh eight ounces of soil 

 which has been dried in an oven or otherwise. Put this on a stove 

 shovel and place it in a fire or on a good bed of coals. It will glow 

 and particles will be burned away. It may be carefully stirred several 

 times so that all parts will be exposed to the air over the fire. If 

 tlie fire is hot the burning process is completed in a few minutes. 

 Then re-weigh the sample. The' loss in weight is chiefly due to the 

 burning out of organic matter and humus. 



The test for organic matter and humus is one of the most 

 valuable tests to be made of any soil. It tells the gardener or 

 farmer whether the soil is rich or poor ; whether it will retain 

 plant-food and moisture well. If several samples of different 

 kinds are tested in this way the importance of the exercise is 

 better understood. Soils from marshes are usually richer in 

 organic matter than upland soils. 



4. Humus Prevents Baking. — Fill three cans nearly full of 

 soils differing as follows: (1) With heavy clay loam; (2) heavy 

 clay loam mixed with one-fourth as much black humus soil; (3) heavy 

 clay loam mixed with one-half as much black humus soil. Wet these 

 all thoroughly and place them in a sunny window until dry. Then 

 note the difference in baking and cracking effects. 



Organic matter plowed into the garden or iield forms 

 humus and helps to prevent its baking and cracking (Fig. 64). 

 The samples in this case should be examined thoroughly with 

 the fingers to note the difference in pulverizing. The one 

 containihg most humus should pulverize most readily. A gar- 

 den containing much humus is more readily kept in good tilth. 



In garden practice it is found that soils containing well- 

 rotted manure or other organic matter are less subject to the 



