Ontario Teachers' Manuals: Nature Study

by Ontario. Department of Education

Try to find the proportion of vegetable matter in each of the following: loams from various sources, sand, clay, gravel. The last three will show scarcely any change. This experiment will give rise to some good arithmetical problems in fractions.

WATER IN SOILS

5. Compare a handful of fresh garden soil with the same soil dried. Note the glistening of the fresh soil, also its weight and darker colour. The fresh soil admits of packing though no water can be squeezed from it. In its best condition, the water of the soil adheres as a film of moisture about every particle. Free water is to be avoided since it excludes the air from the soil.

6. Equal weights of soils of different kinds and degrees of fineness are placed in funnels or in inverted bottles with bottoms removed. Water is then slowly added to each until it begins to drop from the lower end. From this is seen (1) the great value of humus as a water holder, (2) the advantage of fine soil over coarse. For retention of water by absorption, consult Nature Study and Life, Hodge, page 382.

7. Take two wooden boxes (chalk boxes will do), fill one box with moist sand and the other with moist leaf-mould. Weigh the boxes separately and leave them for three or four days in a warm room. Weigh again and note decrease from evaporation. The sand dries out much faster than the humus. Test with clay, gravel, and loam, also with mixtures of these and leaf-mould.

8. Take three paint cans; punch holes in the bottoms. Fill each with good soil well shaken down. Stand the cans in water till the tops are moist, then place them in a warm, dry place. Loosen the soil on the top of No. 1 to a depth of one inch; on No. 2 to a depth of two inches; leave No. 3 untouched. Find out after a few days which is drying out fastest. How may soil be treated so as to lessen evaporation of water?

DRAINAGE

9. Gravel and sand allow water to run away rapidly, but where the soil is fine or closely packed as in clay soils, under-drains are necessary (1) to carry off the surplus water, (2) to allow air to enter the soil, (3) to warm the soil (wet soil is colder than dry).

Take two equal-sized tin cans, make several holes in the bottom of one, place therein a layer of broken pottery or stones, and fill with good soil. Fill the other with similar soil but make no holes for drainage. Plant in each can a healthy plant of the same size and kind. Water both till the soil is saturated and continue watering every two or three days for six weeks. Note (1) the progress of the plants, (2) the temperature of the soils, (3) which plant has the largest and deepest roots. (See Bulletin 174, Ontario Department of Agriculture.)

10. Take five equal-sized boxes, provide for drainage, and fill No. 1 with wood, earth, or humus, No. 2 with clay, No. 3 with sand, No. 4 with a mixture of clay and humus, No. 5 with a mixture of sand and humus. Plant corn in each box, set in a warm room, and keep watered for two or three weeks. Note in which case growth is most rapid. Set boxes in a dry place and cease watering. Which suffers most from the drought? Which bakes hardest in the sun? Test the temperature of each after watering and standing in the sun for an hour. Sand is warmer than clay, also the presence of humus raises the temperature. This item is important, since most seeds decay instead of sprouting if the temperature is below 45° Fahrenheit.