The First Book of Farming - C. L. Goodrich

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a slip or cutting of Wandering Jew (called also inch plant, or tradescantia, and spiderwort), or some other plant that roots readily in water. Then pour on top of the boiled water about a quarter of an inch of oil—lard oil or cotton-seed oil or salad oil. This is to prevent the absorption of air. In a few days roots will appear on the slip in the hydrant water, while only a very few short ones, if any, will appear in the boiled water, and they will soon cease growing. Why is this? To answer this question, try another experiment. Take two bottles, filled as before, one with hydrant water and the other with boiled water; drop into each a slip of glass or a spoon or piece of metal long enough so that one end will rest on the bottom and the other against the side of the bottle, and let stand for an hour or so (Fig. 17). At the end of that time bubbles of air will be seen collecting on the glass or spoon in the hydrant water, but none in the boiled water. This shows us that water contains more or less air, and that boiling the water drives this air out. The cutting in the boiled water did not produce roots because there was no air in it and the oil kept it from absorbing any.

      Experiment.—Into some tumblers of moist sand put cuttings of several kinds of plants that root readily (Fig. 18), geranium, tradescantia, begonia, etc. Put cuttings of same plants into tumblers filled with clay that has been wet and stirred very thoroughly, until it is about the consistency of cake batter. Keep the sand and puddled clay moist; do not allow the clay to crack, which it will do if it dries. The cuttings in the sand will strike root and grow, while most, if not all, those in the clay will soon die. The reason for this is that the sand is well ventilated and there is sufficient air for root development, while the clay is very poorly ventilated, and there is not sufficient air for root growth.

      These experiments show us that to develop and do their work roots need air or a well-ventilated soil.

      We have found the conditions which are necessary for the growth and development of plant roots, namely:

       A firm, mellow soil.

       A moist soil.

       A soil supplied with available plant food.

       A warm soil.

       A ventilated soil.

      These are the most important facts about plant growth so far as the plant grower is concerned. In other words, these conditions which are necessary for root growth and development are the most important truths of agriculture, or they are the foundation truths or principles upon which all agriculture is based. Having found these conditions, the next most important step is to find out how to bring them about in the soil, or, if they already exist, how to keep them or to improve them. This brings us, then, to a study of soils.

      FIG. 12.

       To show where growth in length of the root takes place. Forty hours before the photograph was taken the tip of the root was ¼ inch from the lowest thread. The glass cover was taken from this in order to get a good picture of the root.ToList

      FIG. 13.

       Radish seeds sprouted on dark cloth. To show root hairs.ToList

      FIG. 14.

       To show how water gets into the roots of plants. Water passed up into the egg through the skin, or membrane, and forced the contents up the glass tube until it began to overflow.ToList

      FIG. 15.

       To show osmose (see page 19).ToList

      

       Table of Contents

       Table of Contents

      The soil considered agriculturally, is that part of the earth's crust which is occupied by the roots of plants and from which they absorb food and moisture.

      RELATION OF SOIL TO PLANTS

      We have learned that plant roots penetrate the soil to hold the plant in a firm and stable position, to absorb moisture and with it plant food. We learned also that for roots to do these things well, the soil in which they grow must be mellow and firm, and must contain moisture and plant food, air must circulate in its pores and it must be warm.

      How can we bring about these conditions? To answer this question intelligently it will be necessary for us to study the soil to find out something about its structure, its composition, its characteristics; also, how it was made and what forces or agencies were active in making it. Are these forces acting on the soil at the present time? Do they have any influence over the conditions which are favorable or unfavorable to plant growth? If so, can we control them in their action for the benefit or injury of plants?

      We will begin this soil study with an excursion and a few experiments.

      Go to the field. Examine the soil in the holes dug for the root lessons, noticing the difference between the upper or surface soil and the under or subsoil. Examine as many kinds of surface soils and subsoils as possible, also decayed leaf mould, the black soil of the woods, etc. If there are in the neighborhood any exposed embankments where a road has been cut through a hill, or where a river or the sea water has cut into a bank of soil, visit them and examine the exposed soils.

      Experiment.—Place in separate pans, dishes, plates, boxes, or on boards, one or two pints each of sand, clay, decayed vegetable matter or leaf mould or woods soil, and garden soil. The soil should be fresh from the field. Examine the sand, clay and leaf mould, comparing them as to color; are they light or dark, are they moist or not? Test the soils for comparative size of particles by rubbing between the fingers (Fig. 19), noticing if they are coarse or fine, and for stickiness by squeezing in the hand and noting whether or not they easily crumble afterwards.

      Experiment.—Take samples, about a teaspoonful, of sand, clay and leaf mould. Dry them and then place each in an iron spoon or on a small coal shovel and heat in stove to redness. It will be found that the leaf mould will smoke and burn, and will diminish in amount, while the sand and clay will not.

      Experiment.—Take two wide-mouthed bottles; fill both nearly full of water. Into one put about a teaspoonful of clay and into the other the same amount of sand; shake both bottles thoroughly and set on table to settle (Fig. 20). It will be found that the sand settles very quickly and the clay very slowly.

      As the result of our three experiments

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