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Read and translate the text with the help of a dictionary. The modern classification of soils began with the Russian scientist Docuchaev in the 1880s



The modern classification of soils began with the Russian scientist Docuchaev in the 1880s. Soil surveys in the US, Europe and Canada began only a few years later. How do we classify soils? We could probably develop many classifications based upon how soils

1. were formed by the environment.

2. could be used for crop production

3. could be used for building.

Today we use a scientific taxonomy based upon the soil’s morphology (or its shape and form). From this classification we can interpret important facts relating to crop production, management and so on. However, there are many classification systems used throughout the world. Canada has its own, as does the U.S.A. Fortunately, it is relatively easy to translate from one scheme to the other. The Canadian system (and most others) arranges soils into groups based upon the soil profile characteristics.

Why Classify Soil? Classification allows us to communicate our ideas and research about soil and extrapolate them to other similar areas. It also allows us to predict the behavior of soils such as which soils are most subject to flooding or wind erosion? Or which soils will be most likely to have a sulfur deficiency?

Soil Profile It is important to think of soils in three dimensions; i.e. the soil has depth. Understanding the soil profile is essential to be able to classify soils. The formation of the layers or soil horizons is a result of the environmental forces that have acted upon the soil during its formation, often of thousands of years. The colour, texture and structure of each horizon and often its chemical characteristics are used to group soils and form the basis of most systems of soil classification.

The result of all of these forces is soil that develops into layers known as horizons. The first or top 48 inches of these horizons and its' unique set of characteristic is used by soil scientist to classify and name a soil. Just as an oak tree is named due to its' unique characteristics, so is a soil. These horizons collectively are known as a soil profile. The thickness varies with location, and under disturbed conditions: heavy agriculture, building sites or severe erosion for example, not all horizons will be present.

The uppermost is called the organic horizon or O horizon. It consists of detritus, leaf litter and other organic material lying on the surface of the soil. This layer is dark because of the decomposition that is occurring. This layer is not present in cultivated fields.

Below is the A horizon or topsoil. Usually it is darker than lower layers, loose and crumbly with varying amounts of organic matter. In cultivated fields the plowed layer is topsoil. This is generally the most productive layer of the soil. This is the layer that soil conservation efforts are focused.

As water moves down through the topsoil, many soluble minerals and nutrients dissolve. The dissolved materials leach downward into lower horizons.

The next layer is the B horizon or subsoil. Subsoils are usually lighter in color, dense and low in organic matter. Most of the materials leached from the A horizon stops in this zone.

Still deeper is the C horizon. It is a transition area between soil and parent material. Partially disintegrated parent material and mineral particles may be found in this horizon.

At some point the C horizon will give up to the final horizon, bedrock.

Soil Zones There are many ways to classify soils and there are several systems in use worldwide. Most notable is the U.S. system of Soil Taxonomy. This system is used in many countries throughout the world but some countries – Brazil, Canada, France, Russia have developed their own systems. Regardless, all systems recognize the soil as a product of the environment and differ mainly in grouping and horizon definitions.

3.5 Give English equivalents: современная классификация почв, окружающая среда, производство с/х культур, строительство, недостаток серы, городской мусор, цвет почвы, по всему миру.

3.6 Render the text into Russian using no dictionary:

Humus. The humus which consists of the colloidal residue of organic matter has great effects on soil texture and fertility. Whenever it is present in considerable quantity it imports its black or dark - brown colour to the soil and since dark – coloured materials absorbs more of the sun’s heat than light – coloured ones, its presence tends to rise the soil temperature. Moreover, in well aerated soils humus is constantly undergoing oxidation, with liberation of simple compounds of nitrogen which can be taken up by plant roots. Most important is the fact that humus has many of the properties of mineral colloids – it increases the soil’s power of retaining moisture and it absorbs and holds plant nutrient substances. When organic matter is added to light soils the resulting humus tends to bind the mineral particles into crumbs which absorb and hold water like miniature sponges.

It has already been noted that “row”. What is extremely deep rooted and drought resisting, and on all except very light soils gives the best yields in dry and sunny seasons; it is also more resistant to winter frost than either barley or oats.

    Perfect crops of wheat can be grown on heavy loams and clays. Satisfactory crops can be grown on light land in good condition. When wheat is grown on peaty soils quality is usually poor, while the vegetation is luxuriant and the yield of straw very large.

Text 4

Soil fertility

4.1 Read the following international words and translate them: elements, reproduce, macronutrients, micronutrients, cycle, physical, chemical, characteristics, analysis, function, concentration, bacteria, factor, photosynthesis, atmosphere, mechanisms, individual, diffusion, parameters, intensive, industry, problem. 

4.2 Say it in Russian: specific functions, plant nutrition, plant metabolism, nutrient cycle, nutrient deficiency, soil testing, symbiotic association, organic matter, animal waste, the residues, the complex organic molecules, root interception, diffusion, the addition of fertilizers, maintain high yields, natural fertilizers, the underground aquifers.


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