Soil response

Xem 1-20 trên 45 kết quả Soil response
  • The prevailing low food production in sub-Saharan Africa is an issue of great concern especially since Africa south of the Sahara is the only remaining region of the world where per capita food production has remained stagnant. This chapter reviews long-term experiments in Africa in the context of shifting paradigms related to tropical soil fertility management from fi rst external input paradigm right through to the current Integrated Soil Fertility Management (ISFM) approach, which is a culmination of the participatory methods developed along the paradigm shift.

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  • This book is a response to that need for a synthesis. It contains 17 chapters, each prepared by authors who are internation- ally recognized for their knowledge and expertise in a particular area of soil/plant biology.

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  • Abiotic stresses are serious threats to agriculture and the environment which have been exa‐ cerbated in the current century by global warming and industrialization. According to FAO statistics, more than 800 million hectares of land throughout the world are currently salt-af‐ fected, including both saline and sodic soils equating to more than 6% of the world’s total land area. Continuing salinization of arable land is expected to have overwhelming global impact, resulting in a 30% loss of agricultural land over the next 25 years and up to 50% loss by 2050.

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  • “Be it deep or shallow, red or black, sand or clay, the soil is the link between the rock core of the earth and the living things on its surface. It is the foothold for the plants we grow. Therein lays the main reason for our interest in soils.” --- Roy W. Simonson, USDA Yearbook of Agriculture, 1957. The British naturalist Charles Darwin (1809–1882) was probably the first scientist to examine a soil profile and suggest factors responsible for the structure of the various layers.

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  • The same amount of water has been present on our planet for about 4 billion years, since shortly after the Earth was formed. Since then it has cycled through evaporation, condensation, precipitation and surface runoff multiple times. Water scarcity as an abiotic factor ranging from moderate to severe stress levels, accompanied by loss of moisture in the soil, is extremely hard for most organisms to cope with, particularly terrestrial plants and their food-chain dependents.

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  • The papers in this book provide new information on several aspects of soil erosion and applications of the National Resources Inventory (NRI). They were commissioned following a planning workshop in July 1984 and were presented in December 1984 during a national convocation, “Physical Dimensions of the Erosion Problem.” The workshop and convocation were held by the National Research Council's Board on Agriculture in response to a request from the Soil Conservation Service of the U.S.

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  • Cancers of the endometrium, ovary and cervix share certain characteristics. However, etio-pathogenesis of all the gynecological malignancies is yet to be explored. Even though the etiologic factors are generally environmental, the exact cause of each gynecological cancer is not known (Senate Community Affairs References Committee, Commonwealth of Australia, 2006). Worldwide, cancer incidence rates vary widely between different geographic regions and ethnic groups.

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  • Hydrogen peroxide is particularly effective when it reacts with ferrous iron (Fe2+ ) to produce Fenton's Reagent. Ferrous iron may be naturally present in the subsurface soils and/or groundwater, or it can be added as a catalyst solution together with the hydrogen peroxide to produce this aggressive chemical reaction. Hydrogen peroxide in the presence of ferrous iron (Fe2+ ) reacts to form hydroxyl radicals (OH•), ferric iron (Fe3+ ), and hydroxyl ions (OH- ). The hydroxyl ions are very powerful oxidizers, and react particularly with organic compounds.

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  • It is widely accepted that irrigation allows for the increase and stability in agrarian yields, being a necessary tool to support food supplies and necessities for certain raw materials in the world. However, irrigated agriculture is also considered the most significant fresh water consumer and one of the main causes of pollution, degradation and depletion of natural resources. These impacts are primarily related to changes in the water cycle, salinization of agricultural soils, and salinization and pollution of water resources due to the use of agrochemicals....

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  • Next, we examine predictability in both benchmark returns and fund risk loadings. Consider the dogmatist who believes in such a predictability structure (PD-2). This investor would experience a nontrivial utility loss of 15.1 basis points per month (1.8%/ year) in December 2002 if forced to hold the optimal portfolio of the ND. The utility loss is even larger over the course of all 276 monthly investments. This loss averages 21.1 (39) basis points per month over expansions (recessions).

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  • Hedge funds increased in value to €79 billion, driven largely by revaluations of €2.2 billion amid a net transactions outflow of €0.3 billion. The revaluation performance was tempered by the fact that some hedge funds assumed short positions in a positively performing market. Hedge funds have not outperformed other investment strategies in the year to date. Other funds, comprising mostly mixed funds 3 , experienced negligible inflows of €0.2 billion, despite positive revaluations of €5.1 billion, culminating in an increase in overall stock to €152 billion. ...

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  • As minister responsible for human settlements issues in the Norwegian Government, I want to underline the responsibility of governments to take active action to improve the living conditions of the underprivileged in society. In Istanbul we reaffirmed our commitments to the full and progressive realisa- tion of the right to housing and recognised an obliga- tion by Governments to enable people to obtain shelter and to protect and improve dwellings and neighbourhoods. Now – five years later – we still have a long way to go.

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  • This  survey  was  completed  via  the  internet  from  January  7  to  February  20,  2008  by  253  individuals  who  served  on  at  least  one  audit  committee  for  a  publicly  traded  company  in  2007.  Some respondents were also given the option to complete a paper and pencil survey  in  place of the online survey to increase response rate.     While conducting a probability sample with audit committee members is technically possible, it  was not feasible from a cost or time standpoint.

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  • There are 4 million miles of roads in the United States. One hundred years ago, roads were primarily unpaved and had half the number of miles of the present U.S. road system. As the system grew, roads became wider and more complex structurally to provide for more and heavier traffic. New construction technology and greater structural stability were needed to improve the road system. All phases of road development—from construction and use by vehicles to maintenance—affect physical and chemical soil conditions, water flow, and air and water quality.

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  • There has also been recent interest in and some field applications using sodium persulfate (Na2S2O8) to oxidize organic contaminants or to reduce the oxidant demand of native soils before other oxidants are applied to the contamination. Some research has demonstrated that when mixed with ferrous iron as a catalyst, the sulfate free radical (SO4 - ) can be produced, which has an oxidation potential only slightly less than Fenton's Reagent. Field testing of this oxidant to date has primarily involved the destruction of chlorinated organics rather than petroleum hydrocarbons.

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  • The Guest Editors of this volume agreed in advance on the order listed on the title page, although equal editorial effort should be recognized. Vadim Birstein, Robert Boyle and John Waldman convened the 1994 conference that was the source for the original drafts of most of the manuscripts included in this collection. William Bemis put the volume in final shape; he is also responsible for safeguarding the standards of all contributions as the editorial representative of Environmental Biology of Fishes.

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  • Decreases in pH and ANC are often paral- leled by changes in element concentrations including increases in Al +3 concentrations and decreases in Ca +2 . High dissolved Al +3 concen- trations can have toxic effects on many types of aquatic biota, and at extreme levels few aquatic species can survive (Table 1). Organic forms of Al +3 are much less toxic than inorganic forms. Emerging research suggests that Ca +2 concentra- tions in streamwater are also an important bio- logical indicator.

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  • Providing the board conducted one, the previous year’s executive performance eval- uation most likely includes an action plan for the current year, with developmental goals for the executive. Include these in the evaluation; if not attended to, an excel- lent reason needs to be provided. Job description The executive job description should list major areas for which the executive is respon- sible. It’s essential that the board review this in preparation for the job evaluation, espe- cially if your board has never evaluated its director.

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  • Species mixtures are often recommended over single- species cover crops or sod crops because the mixtures tend to use resources more fully and provide a more diverse habitat. Except in situations where a legume would not establish well, or where the nitrogen-fixing power of legumes is not desired, at least one legume and one non-legume are recom- mended. Some growers establish a sod-forming crop between rows of a cash crop, forming a living mulch which provides soil-improving benefits without taking land totally out of vegetable production.

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  • Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Differential photosynthetic and survival responses to soil drought in two evergreen Nothofagus species...

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