CHAPTER X[ToC]
Seed Planting
HOW DEEP SHOULD SEEDS BE PLANTED?
Experiment.—Plant several kernels of corn in moist soil in a glass tumbler or jar. Put one kernel at the bottom and against the side of the glass, place the next one a half inch or an inch higher and an inch and a half to one side of the first seed and against the glass. Continue this till the top of the glass is reached ([Fig. 2]). Leave the last seed not more than one-fourth inch below the top of the soil. The soil should be moist at the start and the seeds should all be against the glass so they can be seen. This can best be done by planting as you fill the glass with soil. Plant peas and beans in the same way. Do not water the soil after planting. Set aside in a warm place and wait for the seeds to come up.
Another method of performing this experiment is to make a box having one side glass ([Fig. 46]). The length and the depth of the box will depend upon the size of the glass you use. Fill the box nearly full of moist soil and plant seeds of corn and beans and peas at depths of one-quarter inch, one inch, two inches, three inches, and four inches. These seeds can best be put in as the box is being filled. Hold each individual seed against the glass with a stick so that when planted they may be seen through the glass. Protect the seeds and roots from light by using a sheet of cardboard, tin or wrapping paper or a piece of board, and set in a warm place.
Many of the seeds planted only one-quarter inch deep will not sprout because the soil about them will probably dry out before they take from it enough moisture to sprout. The one and two-inch deep seeds will probably come up all right. Of the three and four-inch deep seeds, the corn and peas will probably make their way to the surface because they send up only a slender shoot, which can easily force its way through the soil. The deep-planted beans will make a strong effort but will not succeed in forcing their way to the surface because they are not able to lift the large seed-leaves through so much soil, and will finally give up the struggle. If any of the deeper beans do get up, the seed-leaves will probably be broken off and the little plant will starve and be dwarfed. This experiment teaches us that we should plant seeds deep enough to get sufficient moisture for sprouting and yet not so deep that the young seedlings will not be able to force their way to the surface.
Seeds which raise their cotyledons above the soil should not be planted as deep as those which do not. Large, strong seeds like corn, peas, etc., which do not lift their cotyledons above the surface, can be planted with safety at a depth of from one to four or five inches.