a laboratory manual of agriculture for secondary schools

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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: EXERCISE 4 A FIELD LESSON IN SOILS Object. — To study the formation of soils and the effect of location and cultivation upon their depth and value. Explanation. — A soil can usually be separated into three distinct layers: first, the surface soil; second, the subsurface ; and third, the subsoil. The surface soil is the top soil and varies in depth with location and manner of formation. It is distinguished from the subsurface soil by color, the subsurface soil being lighter in color. The subsoil lies immediately below the subsurface soil and is also distinguished from the subsurface soil by having a lighter color. The subsurface soil is intermediate between the soil and subsoil in both location and color. The different layers of the soil differ in texture, that is, in the size of the soil particles. Usually the surface soil has a slightly coarser texture than the subsurface or subsoil. Equipment. — 1. A soil auger. 2. A piece of oilcloth eighteen inches square. Directions. — Go to a near-by field in which there is a hill. Examine the soil on the level land at the top of the hill, on a steep slope, and in the valley at the bottom of the slope. Make an examination of the soil in each place as follows: Select the exact spot to be examined and clear the surface of the ground of grass and other vegetation. Place the auger over the spot to be examined and give it a few turns, forcing it into the ground four or five inches. Remove the auger with the soil. In pulling the auger a slight backward turn will enable the auger to be pulled with greater ease, and prevent the caving in of the soil around the auger hole. Remove the soil from the auger and place it in a pile on the oilcloth provided for the purpose. Repeat this operation, forcing the auger down a few i... --This text refers to an alternate Paperback edition.
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