Read the following text and speak about importance of humus in the soil fertility
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.
2.12 Read the following text without dictionary and say what a new information you’ve got
Organic Matter and Essential Elements. Since all plants require 16 elements for proper growth it is logical to conclude that the dead remains of these plants, like manure contain all essential elements.
Organic matter, in addition to containing elements essential for plants, also contains elements necessary for livestock and man. These are sodium, cobalt, and iodine which are essential for animals but not for plants. Organic matter also contains traces of nickel and gold; in fact most of the elements in nature are found in plants.
Although organic matter contains all of the elements necessary for plant growth, these elements may not always be in the right balance for producing maximum crop yields.
3.1 Read the following international words and translate them:synthetic, periodic, industries, factor, position, reaction, toxic, physically, cultivation, erosion, micro-flora, micro-fauna, character, substance, portion, action, control, operation, commercial, maximum, effect, individual, limiting, practice.
3.2 Read the following words:in spite of, subsequent, inherent, bulky, maintenance, productivity, amenable, ameliorate, relationship, source, although, availability, immediately, supplemented, value, succeeding, beneficial, whilst, capacity, drought, appropriate, until, beyond, figure, adequate, necessarily, advantages, point of view, frequently, reduction.
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