TEXT 6 STRUCTURE OF SOIL

When soil particles aggregate, they form clumps of soil that are called peds. Most peds range from less than ½ to 6 inches (1.3 to 15 centimeters) in diameter. Their shape and arrangement determine a soil’s structure. The ability of peds and soil particles to stick together and hold their shape is called consistence.

Most soils contain two or more kinds of structures. Some soils have no definite structure. In some such soils, the peds lack a definite shape or arrangement. In others, the particles do not aggregate.

There are three main kinds of soil structures: (1) platelike, (2) prismlike, and (3) blocklike. Platelike peds are thin, horizontal plates that occur in any horizon. Prismlike peds are column-shaped subsoil structures. Blocklike peds look like blocks with flat or curved sides. Large, flat –sided, blocklike, peds commonly occur in subsoils. Small, rounded, blocklike peds make up most topsoils. They contain more organic matter and hold water and nutrients better than do larger peds.

 

1. Study the following words:

Soil particles, aggregate, clump, peds, shape, arrangement, to stick, consistence, thin, flat, curved, make up, nutrients.

 

2. Define the part of speech of the following words:

Stick, platelike, definite, ability, curved, commonly, nutrients, arrangement, structure, rounded, make up.

 

3. Translate the following derivatives:

Arrangement, arrange, arranging, structures, structural, common, commonly, define, definition, defining, definite.

 

4. Give definitions of the terms ‘topsoil’, ‘subsoil’:

5. Translate the following sentences:

1. Most soils contain two or more kinds of structures.

2. Most peds range from less than ½ to 6 inches in diameter.

3. Small, rounded, blocklike peds make up most topsoils.

4. Some soils have no definite structure.

 

6. Retell the text ‘ Structure of soil’: