Find in Text 1 English equivalents for the following words and expressions and memorize them.
SOIL SCIENCE ENGLISH
Book I
Учебное пособие по английскому языку для студентов факультета почвоведения
Данное учебное пособие предназначено для студентов 2 курса факультета почвоведения, но также может быть использовано на занятиях в группах с магистрантами и аспирантами естественнонаучных специальностей. Основной целью пособия является дальнейшее совершенствование уже полученных навыков чтения, перевода и реферирования. Пособие содержит аутентичные тексты на английском языке, взятые из научной и учебной литературы по почвоведению, поэтому рассчитано на студентов среднего и продвинутого уровней (В2-С1 по Общеевропейской шкале языковой компетенции), освоивших базовый курс профессионального иностранного языка.
CONTENTS
ВВЕДЕНИЕ.. 4
LESSON 1. 5
LESSON 2. 9
LESSON 3. 13
LESSON 4. 17
LESSON 5. 20
LESSON 6. 24
LESSON 7. 27
LESSON 8. 30
LESSON 9. 33
LESSON 10. 37
LESSON 11. 41
LESSON 12. 45
LESSON 13. 49
LESSON 14. 52
Supplement Texts. 56
APPENDIX I 71
APPENDIX II 72
ВВЕДЕНИЕ
Для специалистов сугубо узкого профиля, помимо владения иностранным языком на уровне не ниже В2 по Общеевропейской шкале языковой компетенции, в рабочем и научно-исследовательском контексте деятельности немаловажным остается умение быстро ориентироваться в профессиональной литературе и осуществлять перевод с одного языка на другой письменных и устных текстов узкоспециализированной тематики, которая, как и любая другая специальная тематика, имеет свои особенности.
Эта первая книга из серии Soil Science English имеет своей целью дальнейшее совершенствование уже полученных навыков чтения, перевода и реферирования. Пособие предназначено для студентов 2 курса факультета почвоведения и рассчитано на 2 семестра, а каждый урок – на 1-2 занятия в зависимости от уровня группы. Основным преимуществом данного пособия является целенаправленное и максимальное расширение словарного запаса по специальному английскому языку в сфере почвоведения, что в конечном итоге должно способствовать умению понять основное содержание любого текста (skim reading) по специальности без обращения к словарю. При составлении пособия были использованы неадаптированные английские тексты (часть которых подверглась некоторым сокращениям) из книги Fundamentals of Soil Science (H.D. Foth, 1990), а также из различных интернет ресурсов. Текстовый материал охватывает разноплановую почвоведческую тематику, такую как биология почв, физика почв, химия почв, эрозия почв, минералогия почв, экология почв и др.
Учебное пособие включает 14 основных тематических уроков, где в состав каждого урока входит поурочный словарь, основной текст на английском языке, сопутствующий текст на русском языке и языковые упражнения; 6 дополнительных тематических текстов для дальнейшего расширения словарного запаса и 2 приложения. В приложении 1 представлен примерный план для устного реферирования научной статьи. В приложении 2 содержится справочная информация по чтению наиболее часто встречающихся математических и химических знаков, символов и формул.
Автор выражает глубокую благодарность доктору филологических наук, заведующей кафедрой английского языка для естественных факультетов факультета иностранных языков и регионоведения МГУ имени М.В. Ломоносова, профессору Л.В. Полубиченко за помощь и ценные рекомендации при редактировании данного пособия.
LESSON 1
Find in Text 1 English equivalents for the following words and expressions and memorize them.
1) рост растений
2) поровое пространство
3) абсорбировать воду
4) питательные вещества
5) ингибирующие факторы
6) корневое дыхание
7) плавучесть
8) высокоурожайные культуры
9) непроницаемый
10) водонасыщенная почва
11) расположение корневой системы в поверхностном слое почвы
12) ветровал
13) стебель
14) набор физических свойств
15) химический состав
16) кальцит
17) известняк
18) мел
19) выветривание
20) устойчивые органические соединения
21) гниение
22) разложение
23) почвенный раствор
24) положительно заряженные ионы
25) отрицательно заряженные ионы
26) чрезмерное потребление/поглощение анионов
27) целинные земли
28) пахотные земли
29) животный навоз
30) улучшающие вещества
31) плодородие почв
Translate the text from English into Russian.
TEXT 1
FACTORS OF PLANT GROWTH
The soil can be viewed as a mixture of mineral and organic particles of varying size and composition in regard to plant growth. The particles occupy about 50 percent of the soil’s volume. The remaining soil volume, about 50 percent, is pore space, composed of pores of varying shapes and sizes. The pore spaces contain air and water and serve as channels for the movement of air and water. Pore spaces are used as runways for small animals and are avenues for the extension and growth of roots. Roots anchored in soil support plants and roots absorb water and nutrients. For good plant growth, the root-soil environment should be free of inhibitory factors. The three essential things that plants absorb from the soil and use are: (1) water that is mainly evaporated from plant leaves, (2) nutrients for nutrition, and (3) oxygen for root respiration.
Support for Plants
One of the most obvious functions of soil is to provide support for plants. Roots anchored in soil enable growing plants to remain upright. Plants grown by hydroponics (in liquid nutrient culture) are commonly supported on a wire framework. Plants growing in water are supported by the buoyancy of the water. Some very sandy soils that are droughty and infertile provide plants with little else than support. Such soils, however, produce high-yielding crops when fertilized and frequently irrigated. There are soils in which the impenetrable nature of the subsoil, or the presence of watersaturated soil close to the soil surface, cause shallow rooting. Shallow-rooted trees are easily blown over by wind, resulting in windthrow.
Essential Nutrient Elements
Plants need certain essential nutrient elements to complete their life cycle. No other element can completely substitute for these elements. At least 16 elements are currently considered essential for the growth of most vascular plants. Carbon, hydrogen, and oxygen are combined in photosynthetic reactions and are obtained from air and water. These three elements compose 90 percent or more of the dry matter of plants. The remaining 13 elements are obtained largely from the soil. Nitrogen (N), phosphorus (P), potassium (K), calcium Ca), magnesium (Mg), and sulfur (S) are required in relatively large amounts and are referred to as the macronutrients. Elements required in considerably smaller amount are called the micronutrients. They include boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn). Cobalt (Co) is a micronutrient that is needed by only some plants. Plants deficient in an essential element tend to exhibit symptoms that are unique for that element. More than 40 other elements have been found in plants. Some plants accumulate elements that are not essential but increase growth or quality. The absorption of sodium (Na) by celery is an example, and results in an improvement of flavor. Sodium can also be a substitute for part of the potassium requirement of some plants, if potassium is in low supply. Silicon (Si) uptake may increase stem strength, disease resistance, and growth in grasses.
Most of the nutrients in soils exist in the minerals and organic matter. Minerals are inorganic substances occurring naturally in the earth. They have a consistent and distinctive set of physical properties and a chemical composition that can be expressed by a formula. Quartz, a mineral composed of SiO2, is the principal constituent of ordinary sand. Calcite (CaCO 3) is the primary mineral in limestone and chalk and is abundant in many soils. Orthclase-feldspar (KAISi3O8) is a very common soil mineral, which contains potassium. Many other minerals exist in soils because soils are derived from rocks or materials containing a wide variety of minerals. Weathering of minerals brings about their decomposition and the production of ions that are released into the soil water. Since silicon is not an essential element, the weathering of quartz does not supply an essential nutrient, plants do not depend on these minerals for their oxygen. The weathering of calcite supplies calcium, as Cat+, and the weathering of orthoclase releases potassium as K+. The organic matter in soils consists of the recent remains of plants, microbes, and animals and the resistant organic compounds resulting from the rotting or decomposition processes. Decomposition of soil organic matter releases essential nutrient ions into the soil water where the ions are available for another cycle of plant growth. Available elements or nutrients are those nutrient ions or compounds that plants and microorganisms can absorb and utilize in their growth. Nutrients are generally absorbed by roots as cations and anions from the water in soils, or the soil solution. The ions are electrically charged. Cations are positively charged ions such as Ca t and K+ and anions are negatively charged ions such as NO3- (nitrate) and H 2PO4 – (phosphate).The amount of cations absorbed by a plant is about chemically equal to the amount of anions absorbed. Excess uptake of cations, however, results in excretion of H+ and excess uptake of anions results in excretion of OH- or HCO 3 – to maintain electrical neutrality in roots and soil.
In nature, plants accommodate themselves to the supply of available nutrients. Seldom or rarely is a soil capable of supplying enough of the essential nutrients to produce high crop yields for any reasonable period of time after natural or virgin lands are converted to cropland. Thus, the use of animal manures and other amendments to increase soil fertility (increase the amount of nutrient ions) are ancient soil management practices.
(H.D. Foth, Fundamentals of Soil Science)
Answer the questions.
1) Why is soil of great value for humanity?
2) What is soil?
3) What is pore space and what does it contain?
4) What are the 3 essential things that plants absorb from the soil?
5) What are the main functions of soil for plants?
6) What is the difference between macronutrients and micronutrients?
7) What are minerals?
8) What does the soil organic matter consist of?
9) What is soil solution?
10) What is used to increase soil fertility?
LESSON 2
TEXT 2
Water Requirement of Plants
A few hundred to a few thousand grams of water are required to produce 1 gram of dry plant material. Approximately one percent of this water becomes an integral part of the plant. The remainder of the water is lost through transpiration, the loss of water by evaporation from leaves. Atmospheric conditions, such as relative humidity and temperature, play a major role in determining how quickly water is transpired.
The growth of most economic crops will be curtailed when a shortage of water occurs, even though it may be temporary. Therefore, the soil's ability to hold water over time against gravity is important unless rainfall or irrigation is adequate. Conversely, when soils become water saturated, the water excludes air from the pore spaces and creates an oxygen deficiency. The need for the removal of excess water from soils is related to the need for oxygen.
Answer the questions.
1) What is transpiration?
2) Do all plants require the same oxygen level in soils?
3) What is wilting? What causes it?
4) What are the most common inhibitory factors for plants?
5) What is the difference between perennials and annuals in terms of their root systems?
6) Can you describe the process of seed germination in soil?
LESSON 3
TEXT 3
Periodic sampling of corn (Zea maize) root systems and shoots during the growing season revealed a synchronization between root and shoot growth. Four major stages of development were found. Corn has a fibrous root system, and early root growth is mainly by development of roots from the lower stem in a downward and diagonal direction away from the base of the plant. The second stage of root growth occurs when most of the leaves are developing and lateral roots appear and "fill" or space themselves uniformily in the upper 30 to 40 centimeters of soil. Stage three is characterized by rapid elongation of the stem and extension of roots to depths of 1 to 2 meters in the soil. Finally, during stage four, there is the production of the ear or the grain. Then, brace roots develop from the lower nodes of the stem to provide anchorage of the plant so that they are not blown over by the wind. Brace roots branch profusely upon entering the soil and also function for water and nutrient uptake.
Answer the questions.
1) What are the 4 main stages of root development and shoot growth using the example of corn?
2) Why do many crops have considerable uniformity in the lateral distribution of roots?
3) What kind of soil is not suitable for root development?
4) What is mass flow and why is it important?
О корнях растений
При прорастании семян из корешка зародыша образуется главный корень. По мере развития главного корня от него в разные стороны отходят боковые корни. Развившаяся сеть корней образует корневую систему растения. По форме различают два типа корневой системы - стержневую и мочковатую. Корневая система растения обеспечивает снабжение его водой и растворенными в ней минеральными солями, укрепляет растение в почве, участвует в синтезе органических веществ в симбиозе с живущими в почве бактериями и грибами, является вместилищем запасных питательных веществ и органом вегетативного размножения.
Растения способны поглощать все элементы, встречающиеся в земной коре. Количественное соотношение поступающих в корни минеральных элементов зависит от содержания их в почве, от ее влажности и температуры и, конечно, от самого вида растений. Так, например, в одинаковых условиях корни гороха поглощают калия в 3 раза больше, чем натрия, а корни пшеницы - в 20 раз больше! Известны некоторые растения, накапливающие большое количество лития, кобальта, золота и других элементов. Хвощ содержит много кремниевой кислоты.
Механизм поглощения минеральных веществ корнями растений очень важен для физиологии и в то же время весьма сложен. В клетках корня, как и в клетках зеленого листа, протекают сложные реакции. Пища, которую доставляют корни в надземные органы растений, содержит и свободные минеральные элементы, и готовые органические вещества в виде белков, аминокислот, фосфорорганических соединений, соединений серы и железа, алкалоидов и др. От содержания минеральных веществ в растении зависит состав протоплазмы и ее свойства, что в свою очередь определяет характер и интенсивность многих биохимических и физиологических процессов, протекающих в течение всего вегетационного периода в надземных органах.
(Источник: http://www.valleyflora.ru/4-1.html)
LESSON 4
TEXT 4
Diffusion is the movement of nutrients in soil water that results from a concentration gradient. Diffusion of ions occurs whether or not water is moving. When an insufficient amount of nutrients is moved to the root surface via mass flow, diffusion plays an important role. Whether or not plants will be supplied a sufficient amount of a nutrient also depends on the amount needed. Calcium is rarely deficient for plant growth, partially because plants' needs are low. As a consequence, these needs are usually amply satisfied by the movement of calcium to roots by mass flow. The same is generally true for magnesium and sulfur. The concentration of nitrogen in the soil solution tends to be higher than that for calcium, but because of the high plant demand for nitrogen, about 20 percent of the nitrogen that plants absorb is moved to root surfaces by diffusion. Diffusion is the most important means by which phosphorus and potassium are transported to root surfaces, because of the combined effects of concentration in the soil solution and plant demands.
Mass flow can move a large amount of nutrients rapidly, whereas diffusion moves a small amount of nutrients very slowly. Mass flow and diffusion have a limited ability to move phosphorus and potassium to roots in order to satisfy the needs of crops, and this limitation partly explains why a large amount of phosphorus and potassium is added to soils in fertilizers. Conversely, the large amounts of calcium and magnesium that are moved to root surfaces, relative to crop plant needs, account for the small amount of calcium and magnesium that is added to soils in fertilizers.
Summary Statement
The available nutrients and available water are the nutrients and water that roots can absorb. The absorption of nutrients and water by roots is dependent on the surface area-density (cm 2/cm3 ) of roots. Mathematically: uptake = availability x surface area-density
SUMMARY
The concept of soil as a medium for plant growth is an ancient concept and dates back to at least the beginning of agriculture. The concept emphasizes the soil's role in the growth of plants. Important aspects of the soil as a medium for plant growth are: (1) the role of the soil in supplying plants with growth factors, (2) the development and distribution of roots in soils, and (3) the movement of nutrients, water, and air to root surfaces for absorption. Soils are productive in terms of their ability to produce plants.
The concept of soil as a medium for plant growth views the soil as a material of fairly uniform composition. This is entirely satisfactory when plants are grown in containers that contain a soil mix. Plants found in fields and forests, however, are growing in soils that are not uniform. Differences in the properties between topsoil and subsoil layers affect water and nutrient absorption. It is natural for soils in fields and forests to be composed of horizontal layers that have different properties, so it is also important that agriculturists and foresters consider soils as natural bodies. This concept is also useful for persons involved in the building of engineering structures, solving environment problems such as nitrate pollution of groundwater, and using the soil for waste disposal. The soil as a natural body is considered in the next chapter.
(H.D. Foth, Fundamentals of Soil Science)
Answer the questions.
1) What is diffusion?
2) What is soil fertility?
3) What is soil productivity?
4) What factors should be taken into account in terms of any soil management?
5) How do soil scientists measure soil productivity?
6) What is important for soil to produce high yields?
Почвоведение как наука.
Почвоведение — наука о свойствах, динамике, происхождении почв, как естественноисторических образований, как объекта труда и средства сельскохозяйственного производства. Почвоведение в качестве самостоятельной области естествознания оформилось 100 лет назад (основоположник Докучаев). До этого почвоведение рассматривалось как часть агрономии или геологии. Развитие почвоведения делится на додокучаевский и докучаевский периоды. Докучаев сумел объединить две теории в одну (гумусовую и минеральную). Также он установил 5 факторов почвообразования: рельеф, климат, растительность, геология, деятельность человека (он рассматривал почву как часть географической среды).
Почвоведение — зеркало физической географии. Все факторы действуют взаимно. На основании этих факторов были предложены зоны земного шара: северная зона, тундра, лесотундра, тайга, лесостепь, степь, тропики и субтропики. Докучаевым было предложено изучение почв по их генезису. Основным показателем являлась морфология почв. Методы Докучаева сейчас повсеместны. С ним работали Северцев (картографирование и классификация почв), Костычёв (органомическое почвоведение), Кассович (физика и химия почв), Глинка (география и классификация почв), Гедройц (поглотительная способность почв), Высоцкий (гидрологический режим почв), Вильямс (развитие почвенного процесса (Полынов, Ковда, Тюрин, Глазовская). Все они принимали участие в составлении мировой карты почв.
Связь почвоведения с другими науками.
П. связано с физикой, химией, географией, биологией, математикой, геологией и др. П. опирается на разработанные ими фундаментальные законы и методы исследования. Сейчас выделяют: физику, химию, биологию почв, микробиологию, минералогию, микроморфологию, географию, картографию почв. Почва — верхний слой суши земного шара, видоизменённый и продолжающий изменятся под действием биологических и географических факторов.
(Источник: http://all-aboutall.narod.ru/Soil.html)
LESSON 5
TEXT 5
HUMUS - the organic constituent of soil, usually formed by the decomposition of plants and leaves [Latin, literally 'soil'] Oxford Dictionary
Organic farming has as its main basis, the health of the soil. Before the advent of modern agricultural techniques at about the beginning of the 20th century, all soils right across the world were healthy and living. This fertility being the result of thousands of years of careful husbandry where all the plant residues and all the cow and other domestic animal manures were returned to the soil. A wonderful soil microbial life had been built up over these years. This has been documented in many articles on soil written over the centuries.
Modern agricultural science holds the belief that to feed a hungry world and meet the demand for an increase in food supply artificial forms of nitrogen, phosphorous, potash and all micronutrients must be added as some form of chemical salt to grow food. Acid based chemical fertilisers kill off the various soil bacteria, beneficial fungus and earthworms, which support the all important humus, which is the great basis of soil structure. So the soil lost its natural fertility.
Plants now weakened by being fed with artificial fertilisers have developed all kinds of fungus diseases and susceptibility to many insect attacks, and as a consequence a whole regime of chemical plant pesticides and fungicides are now also being used. These chemicals are causing poisonous pollution of the soil, the water and of humans. The end result is that hectares and hectares of farming soils the world over have lost their structure, and are now degraded soils.
Importance of Humus for Soil Structure & Fertility in Soils
Soils that have a high humus content, have abundant living biological activity to convert plant residues, leaf litter, animal dung and various biomass into stable humus.
It is said that the weight of the organisms in the soil, equals the weight of the animals above the ground that soil can support. The micro organisms are bacteria, including rhizobia (nitrogen fixing), phosphate solubilizing bacteria, mycorrhizal fungi, algae, actinomycetes and protozoa. Then there are the macro organisms, such as nematodes, springtails, mites, ants, millipedes and earthworms.
Humus gives the soil the ability to absorb and retain moisture. Such soils do not dry out and require significantly less irrigation.
Humus provides a reservoir for the plant nutrients available in the soil for balanced plant growth.
Humus plays a part in supporting soil bacteria, such as rhizobacta so important for all legume nodulation and other well known bacteria, such as the phosphate solubilizing bacteria.
An exudate from bacterial activity results in polysaccharides (a sticky substance) being released, which helps bind the small soil particles into a nutty crumb structure to a depth of 30cm or more.
Humus also supports the all important mycorryhzal fungi, which form a symbiosis with many plants and are an important factor in the soil food web. The hyphae from these fungi help bind the soil particles to form good soil structure.
(Источник:http://www.biodynamics.in/humus.htm)
Answer the questions.
1) Why were soils more fertile and healthier a century ago?
2) Why do modern agriculturists continue using chemical fertilizers?
3) What are the consequences of using artificial fertilizers?
4) What micro- and macro organisms exist in soil?
5) Why is humus important in terms of irrigation?
6) Why does soil structure depend on its biological microorganisms?
| REMEMBER! |
| alga - algae |
| hypha - hyphae |
| larva - larvae |
ГУМУС 1.
Гумус – это основа жизненной энергии почвы. Чем его больше, тем лучше развиваются растения.
Над созданием гумуса трудятся живущие в земле организмы. Основу сообщества составляют всевозможные бактерии, актиномицеты, микрогрибы, водоросли. Свой вклад в процесс вносят черви, жуки, мокрицы, многоножки – они измельчают и подготавливают растительные остатки для переработки. На вершине этой биологической пирамиды – дождевые черви. Пропуская через себя почву, они оставляют на выходе органоминеральный комплекс, в котором количество доступных для растений элементов возрастает в среднем в одиннадцать раз.
Почвы состоят из органической и минеральной части (глина, песок). Но минеральная составляющая – это только каркас. Чуть ли не все свойства почвы напрямую зависят от содержания в ней гумуса.
Как известно, земля средней полосы России гумусом не богата (от 1 до 5%). В подзолистых его немного, легкие, песчаные просто бедны. Зато в черноземах содержится 10–12% гумуса, а в странах Западной Европы эта цифра поднимается до 15%.
Одна из важнейших функций гумуса – накопление минерального питания растений. На его многофункциональных молекулах, как на складах, удерживаются минеральные составляющие. Такое устройство позволяет почве оставаться плодородной даже при значительных осадках и обилии талых вод.
Кроме этого, гумус способствует созданию хорошей структуры почвы. Гумусные почвы всегда рыхлые, комкообразные, воздухо- и влагоемкие. Вот почему даже в сильную жару в лесу или на лугу ничто не «сгорает», в отличие от обрабатываемых участков, где у почвы пылеобразная структура.
( Источник: http://www.supersadovnik.ru/article_agro.aspx?id=1001341)
ГУМУС 2. Возвращение.
Количество гумуса в почве служит основным показателем ее плодородия. Гумусовые вещества и промежуточные продукты разложения органических остатков активно участвуют в почвообразовании.
Большое значение имеет гумус в формировании профиля почвы. В почвах, где накапливается много гуминовых кислот, формируется хорошо выраженный гумусовый горизонт с высокой поглотительной способностью катионов. Если почва богата кальцием, гуминовые кислоты образуют гуматы кальция, участвующие в создании водопрочной пористой и зернистой структуры. Эти почвы имеют благоприятные водно - воздушные свойства и хороший питательный режим.
Если в составе гумуса много фульвокислот, что свойственно почвам с постоянно или временно избыточным увлажнением, эти почвы легко обедняются кальцием, магнием, калием и другими основаниями, так как фульвокислоты образуют с ними растворимые соли, мигрирующие вниз по профилю с просачивающейся влагой. Реакция почвы становится кислой, начинается разрушение силикатов и алюмосиликатов.
В гумусе накапливаются и сохраняются основные элементы питания растений. При его разложении в почвенный раствор поступают азот и элементы зольного питания растений, а в приземный слой воздуха - углекислота, служащая источником углеродного питания растений. Однако разложение гумуса в почве идет более замедленными темпами, чем разложение свежих органических остатков.
Обладая коллоидными свойствами, гумусовые вещества склеивают и цементируют механические элементы почвы в структурные агрегаты, тем самым улучшая тепловые и водно - воздушные свойства почвы. Водорастворимые формы гуминовых кислот, разлагаясь, поглощаются растениями, активизируют окислительно - восстановительные процессы, а также стимулируют рост и развитие растений. Придавая почве темную окраску, гумус способствует активному поглощению лучистой энергии Солнца.
Сохранение и накопление гумуса в почве - одна из важнейших задач агрономов. При неправильных системах обработки и удобрения почв, а также размещения и чередования культур происходит потеря гумуса, тогда как соответствующими приемами гумус можно не только сохранить, но и заметно увеличить его запасы, а также улучшить качественный состав.
Основными мероприятиями, обеспечивающими накопление гумуса в почве, являются систематическое внесение органических удобрений (навоз, торфокомпоста, сидерация), травосеяние, известкование кислых почв, гидротехническая мелиорация, чередование культур (севооборот) и правильная обработка, обеспечивающая в почвах нормальные условия водно - воздушного и теплового режимов, а также защиту почв от водной и ветровой эрозии. При планировании и осуществлении этих мероприятий необходимо учитывать природные условия зоны и специфические особенности конкретной хозяйственной территории.
(Источник: http://enc.sci-lib.com/article0001046.html)
LESSON 6
TEXT 6
SOIL AS A NATURAL BODY
Sediment Parent Materials
Weathering and erosion are two companion and opposing processes. Much of the material lost from a soil by erosion is transported downslope and deposited onto existing soils or is added to some sediment at a lower elevation in the landscape. This may include alluvial sediments along streams and rivers or marine sediments along ocean shorelines. Glaciation produced extensive sediments in the northern part of the northern hemisphere. Four constrasting parent material-soil environments are shown in Figure 2.3. Bare rock is exposed on the steep slopes near the mountaintops. Here, any weathered material is lost by erosion and no parent material or soil accumulates. Very thick alluvial sediments occur in the valley. Very thick glacial deposits occur on the tree-covered lateral moraine that is adjacent to the valley floor along the left side. An intermediate thickness of parent material occurs where trees are growing below the bare mountaintops and above the thick alluvial and moraine sediments. Most of the world's soils have formed in sediments consisting of material that was produced by the weathering of bedrock at one place and was transported and deposited at another location. In thick sediments or parent materials, the formation of soil layers is not limited by the rate of rock weathering, and several soil layers may form simultaneously.
SOIL FORMATION
Soil layers are approximately parallel to the land surface and several layers may evolve simultaneously over a period of time. The layers in a soil are genetically related; however, the layers differ from each other in their physical, chemical, and biological properties. In soil terminology, the layers are called horizons. Because soils as natural bodies are characterized by genetically developed horizons, soil formation consists of the evolution of soil horizons. A vertical exposure of a soil consisting of the horizons is a soil profile.
(H.D. Foth, Fundamentals of Soil Science)
Answer the questions.
1) What is parent material? How does its formation occur?
2) What is bedrock?
3) What is the difference between parent material and bedrock?
4) What is the difference between weathering and erosion?
5) What is a soil horizon?
6) What is a soil profile?
ВЫВЕТРИВАНИЕ
Выветриваниемназывают процесс механического разрушения и химического изменения горных пород и составляющих их минералов. На горную породу совместно воздействуют живые организмы, вода, газы и колебания температур. Все эти факторы оказывают на породу разрушающее действие одновременно. В зависимости от преобладающего фактора различают три формы выветривания: физическое, химическое и биологическое. Вместе с тем следует иметь в виду, что всякое изменение химического состава породы приводит к изменению ее физических свойств.
Физическое выветривание — это механическое разрушение горных пород без изменения химического состава. Главный фактор физического выветривания — колебание суточных и сезонных температур. При нагревании происходит расширение минералов, входящих в горную породу. Таким образом, в течение длительного времени образуется множество трещин, приводящих к полному механическому разрушению горной породы. Разрушенные породы приобретают способность пропускать и удерживать воду. В результате раздробления массивных пород сильно увеличивается общая поверхность, с которой соприкасаются вода и газы, что обусловливает протекание химических процессов.
Химическое выветривание приводит к образованию новых соединений и минералов, отличающихся по химическому составу от первичных минералов. Оно осуществляется под воздействием воды с растворенными в ней солями и диоксидом углерода, а также кислорода воздуха. Химическое выветривание включает следующие процессы: растворение, гидролиз, гидратацию, окисление.
Биологическое выветривание — это механическое разрушение и химическое изменение горных пород под воздействием живых организмов и продуктов их жизнедеятельности. Этот вид выветривания связан с почвообразованием. Если при физическом и химическом выветривании происходит только превращение магматических горных пород в осадочные, то при биологическом выветривании образуется почва, в ней накапливаются элементы питания растений и органическое вещество.
В почвообразовательном процессе участвуют бактерии, грибы, актиномицеты, зеленые растения, а также различные животные (дождевые черви, землеройные животные, насекомые и др.). Горные породы разлагают и многочисленные микроорганизмы, а также водоросли, лишайники, мхи и корни растений.
Таким образом, под влиянием физического, химического и биологического выветривания горные породы, разрушаясь, обогащаются мелкоземом, глинистыми и коллоидными частицами, приобретают поглотительную способность, становятся влагоемкими, водо- и воздухопроницаемыми; в них накапливаются элементы питания растений и органическое вещество. Это приводит к возникновению существенного свойства почвы — плодородия, которого не имеют горные породы.
(Источник: http://studopedia.ru/2_99461_rol-relefa-kak-faktora-pochvoobrazovaniya.html)
LESSON 7
TEXT 7
Soil-Forming Processes
Horizonation (the formation of soil horizons) results from the differential gains, losses, transformations, and translocations that occur over time within various parts of a vertical section of the parent material. Examples of the major kinds of changes that occur to produce horizons are: (1) addition of organic matter from plant growth, mainly to the topsoil; (2) transformation represented by the weathering of rocks and minerals and the decomposition of organic matter; (3) loss of soluble components by water moving downward through soil carrying out soluble salts; and, (4) translocation represented by the movement of suspended mineral and organic particles from the topsoil to the subsoil.
SOILS AS NATURAL BODIES
Various factors contribute to making soils what they are. One of the most obvious is parent material. Soil formation, however, may result in many different kinds of soils from a given parent material. Parent material and the other factors that are responsible for the development of soil are the soil-forming factors.
The Soil-Forming Factors
Five soil-forming factors are generally recognized: parent material, organisms, climate, topography, and time. It has been shown that Bt and Bhs horizon development is related to the clay and sand content within the parent material and/or the amount of clay that is formed during soil evolution.
Grass vegetation contributes to soils with thick A horizons because of the profuse growth of fine roots in the upper 30 to 40 centimeters of soil. In forests, organic matter is added to soils mainly by leaves and wood that fall onto the soil surface. Small-animal activities contribute to some mixing of organic matter into and within the soil. As a result, organic matter in forest soils tends to be incorporated into only a thin layer of soil, resulting in thin A horizons. The climate contributes to soil formation through its temperature and precipitation components. If parent materials are permanently frozen or dry, soils do not develop. Water is needed for plant growth, for weathering, leaching, and translocation of clay, and so on. A warm, humid climate promotes soil formation, whereas dry and/or cold climates inhibit it.
The topography refers to the general nature of the land surface. On slopes, the loss of water by runoff and the removal of soil by erosion retard soil formation. Areas that receive runoff water may have greater plant growth and organic matter content, and more water may percolate through the soil. The extent to which these factors operate is a function of the amount of time that has been available for their operation. Thus, soil may be defined as: unconsolidated material on the surface of the earth that has been subjected to and influenced by the genetic and environmental factors of parent material, climate, organisms, and topography, all acting over a period of time.
SUMMARY
The original source of all mineral soil parent material is rock weathering. Some soils have formed directly in the products of rock weathering at their present location. In these instances, horizon formation may be limited by the rate of rock weathering, and soil formation may be very slow. Most soils, however, have formed in sediments resulting from the erosion, movement, and deposition of material by glaciers, water, wind, and gravity.
Soils that have formed in organic sediments are organic soils. The major soil-forming processes include: (1) humification and accumulation of organic matter, (2) rock and mineral weathering, (3) leaching of soluble materials, and (4) the eluviation and illuviation of colloidal particles. The operation of the soil formation processes over time produces soil horizons as a result of differential changes in one soil layer, as compared to another. The master soil horizons or layers include the O, A, E, B, C, and R horizons. Different kinds of soil occur as a result of the interaction of the soil-forming factors: parent material, organisms, climate, topography, and time. Landscapes are composed of three-dimensional bodies that have naturally (genetically) developed horizons. These bodies are called soils. Prudent use of soils depends on a recognition of soil properties and predictions of soil behavior under various conditions.
(H.D. Foth, Fundamentals of Soil Science)
Answer the questions.
1) What is horizonation?
2) What changes occur in the process of horizonation?
3) What are the main soil-forming factors?
4) What is leaching?
5) What is topography?
6) What processes take place during soil-formation?
LESSON 8
TEXT 8
SOIL PHYSICAL PROPERTIES
Physically, soils are composed of mineral and organic particles of varying size. The particles are arranged in a matrix that results in about 50 percent pore space, which is occupied by water and air. This produces a three-phase system of solids, liquids, and gases. Essentially, all uses of soils are greatly affected by certain physical properties. The physical properties considered in this chapter include: texture, structure, consistence, porosity, density, color, and temperature.
SOIL TEXTURE
The physical and chemical weathering of rocks and minerals results in a wide range in size of particles from stones, to gravel, to sand, to silt, and to very small clay particles. The particle-size distribution determines the soil's coarseness or fineness, or the soil's texture. Specifically, texture is the relative proportions of sand, silt, and clay in a soil.
Particle Size Analysis
Sieves can be used to separate and determine the content of the relatively large particles of the sand and silt separates. Sieves, however, are unsatisfactory for the separation of the clay particles from the silt and sand. The hydrometer method is an empirical method that was devised for rapidly determining the content of sand, silt, and clay in a soil. In the hydrometer method a sample (usually 50 grams) of air-dry soil is mixed with a dispersing agent (such as a sodium pyrophosphate solution) for about 12 hours to promote dispersion. Then, the soil-water suspension is placed in a metal cup with baffles on the inside, and stirred on a mixer for several minutes to bring about separation of the sand, silt, and clay particles. The suspension is poured into a specially designed cylinder, and distilled water is added to bring the contents up to volume.
SOIL STRUCTURE
Texture is used in reference to the size of soil particles, whereas structure is used in reference to the arrangement of the soil particles. Sand, silt, and clay particles are typically arranged into secondary particles called peds, or aggregates. The shape and size of the peds determine the soil's structure.
Importance of Structure
Structure modifies the influence of texture with regard to water and air relationships and the ease of root penetration. The macroscopic size of most peds results in the existence of interped spaces that are much larger than the spaces existing between adjacent sand, silt, and clay particles. Note the relatively large cracks between the structural peds in the claypan (Bt horizon) shown in Figure 3.6. The peds are large and in the shape of blocks or prisms, as a result of drying and shrinkage upon exposure. When cracks are open, they are avenues for water movement. When this soil wets, however, the clay expands and the cracks between the peds close, causing the claypan horizon to become impermeable. Root penetration and the downward movement of water, however, are not inhibited in the B horizon of most soils.
(H.D. Foth, Fundamentals of Soil Science)
Answer the questions.
1) What are the main soil physical properties?
2) What is the particle-size distribution and what purpose does it serve?
3) What methods are used to analyze soil particle-size distribution?
4) Why is it important to determine soil texture and soil structure?
LESSON 9
TEXT 9
SOIL CONSISTENCE
Consistence is the resistance of the soil to deformation or rupture. It is determined by the cohesive and adhesive properties of the entire soil mass. Whereas structure deals with the shape, size, and distinctiveness of natural soil aggregates, consistence deals with the strength and nature of the forces between the sand, silt, and clay particles. Consistence is important for tillage and traffic considerations. Dune sand exhibits minimal cohesive and adhesive properties, and because sand is easily deformed, vehicles can easily get stuck in it. Clay soils can become sticky when wet, and thus make hoeing or plowing difficult.
Soil Consistence Terms
Consistence is described for three moisture levels: wet, moist, and dry. A given soil may be sticky when wet, firm when moist, and hard when dry. A partial list of terms used to describe consistence includes:
1. Wet soil-nonsticky, sticky, nonplastic, plastic
2. Moist soil-loose, friable, firm
3. Dry soil-loose, soft, hard
Plastic soil is capable of being molded or deformed continuously and permanently, by relatively moderate pressure, into various shapes when wet. Friable soils readily break apart and are not sticky when moist. Two additional consistence terms for special situations are cemented and indurated. Cementation is caused by cementing agents such as calcium carbonate, silica, and oxides of iron and aluminum. Cemented horizons are not affected by water content and limit root penetration. When a cemented horizon is so hard that a sharp blow of a hammer is required to break the soil apart, the soil is considered to be indurated.
SOIL COLOR
Color is about the most obvious and easily determined soil property. Soil color is important because it is an indirect measure of other important characteristics such as water drainage, aeration, and the organic matter content. Thus, color is used with other characteristics to make many important inferences regarding soil formation and land use.
SOIL TEMPERATURE
Below freezing there is extremely limited biological activity. Water does not move through the soil as a liquid and, unless there is frost heaving, time stands still for the soil. A soil horizon as cold as 5° C acts as a deterrent to the elongation of roots. The chemical processes and activities of microorganisms are temperature dependent. The alternate freezing and thawing of soils results in the alternate expansion and contraction of soils. This affects rock weathering, structure formation, and the heaving of plant roots. Thus, temperature is an important soil property.
Location and Temperature
In the northern hemisphere, soils located on southern slopes have a higher temperature than soils on north-facing slopes. Soils on south-facing slopes are more perpendicular to the sun's rays and absorb more heat energy per unit area than do soils on northern slopes. This is very obvious in tundra regions where soils on north-facing slopes may have permanently frozen subsoil layers within the normal rooting depth of trees, whereas soils on southern slopes do not.
Large bodies of water act as heat sinks and buffer temperature changes nearby. In the spring and fall the temperature changes more slowly and gradually in the area adjacent to the Great Lakes than at locations further inland. Near these lakes in the spring, the temperatures of both air and soil increase slowly, which delays the blossoms on fruit trees and thereby reduces the hazard of late spring frosts. Killing frosts in the fall are delayed, resulting in an extension of the growing season. As a consequence, production of vine and tree fruits is concentrated in areas adjacent to the Great Lakes.
Permafrost
When the mean annual soil temperature is below 0° C, the depth of freezing in winter may exceed the depth of thawing in summer. As a consequence, a layer of permanently frozen soil, called permafrost, may develop. Permafrost ranges from material that is essentially all ice to frozen soil, which appears ordinary except that it is frozen and hard.
SUMMARY
Soil physical properties affect virtually every use made of the soil. Texture relates to the amount of sand, silt, and clay in the soil and structure relates to the arrangement of the sand, silt, and clay into peds. Texture and structure greatly affect plant growth by influencing water and air relationships. Soils that expand and shrink with wetting and drying affect the stability of building foundations. About one half of the volume of mineral soils is pore space. Such soils have a bulk density of about 1.3 g/cm 3 and 50 percent porosity. In soils with favorable conditions for water retention and aeration, about one half of the porosity is macropore space and one half is micropore space. Soil color is used as an indicator of organic matter content, drainage, and aeration. Soil temperature affects plant growth. Soil temperature is greatly affected by soil color, water content, and the presence or absence of surface materials, such as mulches. Permafrost occurs in soils with average temperature below freezing.
(H.D. Foth, Fundamentals of Soil Science)
Answer the questions.
1) How can soil be described in terms of soil consistence?
2) What is the difference between particle density and bulk density?
3) Why is soil colour important?
4) What are the most common colours of soil?
5) How does temperature affect soil?
6) What is the most suitable soil temperature for plant growth?
7) What is permafrost?
Match the synonyms.
| cohesive | wet |
| adhesive | to concern |
| to deal with | cultivation |
| vehicle | bound |
| strength | sticky |
| moist | to till |
| tillage | transport |
| to plow (plough) | force |
| hazard |