Ontario Teachers' Manuals: Nature Study Part 46

REFERENCES

Parsons: _How to Plan the Home Grounds._ Doubleday. $1.00

Waugh: _The Landscape Beautiful._ Judd. $2.00

Department of Education: _Improvement of School Grounds._

SOIL STUDIES

WEIGHT

Using a balance, compare weights of equal-sized boxes of different soils, dried and powdered fine. Note the comparative lightness of humus.

Weigh a box of earth taken fresh from the field, from this compute (1) the weight of a cubic foot of such soil, (2) the weight of the soil to the depth of a foot in a ten-acre field.

Repeat the experiment, making it an exercise in percentage.

Fill two gla.s.s tubes (lamp chimneys will do), one with finely powdered clay, the other with sand. Set the tubes in a pan containing water. Note the rise of the water due to capillarity. Through which soil does it rise faster? Farther? Try with other soils. Try with fine soil and also with the same soil in a lumpy condition. From this give a reason (1) for tilling soil, (2) for rolling after seeding.

SUBSOILS

Procure samples of soil from different depths, four inches, eight inches, twelve inches, sixteen inches, etc. Note how the soil changes in colour and texture. In which do plants succeed best? In most fields the richest part of the soil is contained in the upper nine inches; the portion below this is called subsoil. This extends to the underlying rock and is usually distinguished from the upper portion by its lighter colour, poorer texture, and smaller supply of available plant food. The difference is due largely to the absence of humus. The character of the subsoil has an important bearing on the condition of the upper soil. A layer of sand or gravel a few feet below the surface provides natural drainage, but if it be too deep, it may allow the water to run away rapidly, carrying the plant food down below the roots of the plants. A hard clay subsoil will render the top too wet in rainy weather and too dry in droughts, because of the small amount of water absorbed. Such a soil is benefited by under-draining. A deep and absorptive subsoil returns water to the surface, by capillary action, as it is needed. The subsoil finally contains a large amount of plant food, which becomes gradually changed into a form in which plants can make use of it. Pupils should find out the character of the subsoil in their various fields at home and its effect on the fertility of the field.

FERTILIZERS

Along with water, the roots take up from the soil various substances that are essential to their healthy growth. Potash, phosphoric acid, nitrogen, calcium, sulphur, magnesium, and iron are needed by plants, but the first three are particularly important. If land is to yield good crops year after year, it must be fertilized, that is, there must be added chemicals containing the above-mentioned plant foods. Land becomes poor from two causes: the plant food in the soil becomes exhausted, and poisonous excretions from the roots of one year's crops act injuriously on those of the next season. Rotating crops will improve both conditions for a while, but eventually the soil will require treatment.

Humus contains plant food and is also an excellent absorbent of the poisonous excretions. It is added as barn-yard manure, leaves, or as a green crop ploughed in.

The chemicals commonly used comprise nitrate of soda, bone meal, sulphate of potash, chloride of potash, lime, ashes, cotton-seed meal, dried blood, super-phosphate, rock phosphate, and basic clay.

EXPERIMENTS:

1. Sow wheat on the same plot year after year and note the result when no fertilizer is used. Sow wheat on another plot, but use good manure.

2. Try the various commercial fertilizers on the school plots, leaving some without treatment.

3. Examine the roots of clover, peas, or beans, and look for nodules.

These show the presence of bacteria, which convert the atmospheric nitrogen into a form in which the plants can use it. Scientific farmers have learned the value of inoculating their soil with these germs. A crop of peas or clover may produce the same result.

4. Observe Nature's method of supplying soil with humus.

SOIL-FORMING AGENTS

There was once a time when the surface of the earth was bare rock. Much of this rock still exists and in many places lies on the surface, but it is usually hidden by a layer of soil. Soil is said to be "rock ground to meal by Nature's millstones". The process is very slow, but it is constantly going on. The pupils should be directed to find evidences of this "grinding".

1. RUNNING WATER.--Brooks, creeks, rain, and the tiny streamlets on the hills all tell us how soil is carried from place to place. Get some muddy water from the river after a heavy rain. Let it settle in a tall jar and observe the fine layer formed.

Wash some pebbles clean, place them in a gla.s.s jar with some clear water, and roll or shake the jar about for a few minutes. Note that the water becomes turbid with fine material worn from the stones. A process similar to this is constantly going on in rivers, lakes, and seas.

Account for the presence of gravel beds now situated far away from any water.

2. ICE GLACIERS.--How do these act on rocks? Show evidences in Ontario as far as these can be ill.u.s.trated from the surroundings, such as polished rocks, boulders, beds of clay, sand, or gravel, small lakes, grooved stones, etc.

3. FROST AND HEAT.--See "Expansion of Solids", pages 189, 190. Look for splintered or cracked stones. Why do farmers plough in the fall?

4. WIND.--In sections near the lakes the action of the wind in moving the sand may be seen and appreciated. There are other places where this work is going on on a smaller scale.

5. PLANTS.--Our study of humus shows the value of vegetable matter in soil. Besides contributing to the soil, plants break up rocks with their roots and dissolve them with acid excretions. It is interesting to study how a bare rock becomes covered with soil. First come the lichens which need no soil; on the remains of these the mosses grow. The roots of mosses and lichens help to disintegrate the rock with their excretions, so that, with frost, heat, air, and rain to a.s.sist, there is a layer of soil gradually formed on which larger plants can live. A forest develops. The trees supply shade from the sun and shelter from the wind, thus r.e.t.a.r.ding evaporation. The roots of the trees hold the soil from being washed away. The dead leaves and fallen stems provide humus, and, on account of the water-holding capacity of humus, the forest floor acts like a sponge, preventing floods in wet seasons and droughts in dry times.

6. ANIMALS.--Pupils should make a list of all burrowing animals and look for examples. The work of the earthworms is especially interesting. By eating the soil, they improve its texture and expose it to the air.

Their holes admit air and water to the soil. The worms also drag leaves, sticks, and gra.s.s into their holes and thus add to the humus.

Darwin estimated that the earthworms in England pa.s.sed over ten tons of soil an acre through their bodies annually. This is left on the surface and makes a rich top-dressing.

TILLING THE SOIL

1. It makes the soil finer, thus increasing the surface for holding film water and enabling it to conduct more water by capillarity.

2. It saves water from evaporation. (See Experiments 7 and 8, Form III.)

3. It aerates the soil, enabling roots to thrive better.

4. It drains (hence warms) the soil, a.s.suring more rapid growth.

5. It kills weeds.

A large part of the work with soils may be done in connection with the garden studies, though most of the above mentioned experiments may be tried in the school-room. In ungraded schools any of the experiments may be made instructive to all the Forms.

Pupils should be asked to acquaint themselves with the common implements used on the farm. They should ascertain the special service rendered by each. See _Circular 156_, Dominion Department of Agriculture.

GARDEN WORK

The work in gardening for Form IV should be connected with some definite line of experimental work. The garden should be so planned that a part of it can be used exclusively for experimental work. Co-operation with the Farmer's Experimental Union of the Ontario Agricultural College at Guelph is advisable at this point. The following list of experiments is suggested as suitable for boys especially, but no pupil should attempt more than one experiment each year.

EXPERIMENTS IN PLOTS OUT-OF-DOORS

Experimental plots may be of different sizes, according to the s.p.a.ce available, from a yard square to a rod square or larger. A plot 10 ft. 5 in. by 20 ft. 10 in. is almost 1/200 of an acre, so that the actual yield on such a plot when multiplied by 200 is an approximation of the yield an acre.

1. Testing of varieties of grains, vegetables, or root seeds, including potatoes new to the district.

2. Testing different varieties of clovers and fodder gra.s.ses. These plots should be so situated that they can remain for three years.

3. Thick and thin sowing of grain: Use plots not less than four feet square. They may be tried most easily with wheat, oats, or barley, although any species of grain may be used. Use four plots of the same size, equal in fertility and other soil conditions. In No. 1 put grains of wheat or oats, as the case may be, two inches apart each way. In No.

2 put the grains two inches apart in the row and the rows four inches apart. In No. 3 put the grains four inches apart in the row and the rows four inches apart. In No. 4 put the grains four inches apart in the row and the rows eight inches apart.

If possible, weigh the straw and grain when cut and the grain alone when dry and sh.e.l.led out of the heads.

4. Deep and shallow growing of grain: Use four plots similar to those in experiment No. 3. Put the same amount of seed in the different plots. In No. 1, one inch deep; in No. 2. two inches deep; in No. 3, four inches deep, and in No. 4, six inches deep. Note which is up first, and which gives the best yield and best quality.