Lal, R. Soil-erosion from tropical arable lands and its control. Advances in Agronomy 37 , Lutz, W. The end of world population growth. Nature , Montgomery, D. Dirt: The Erosion of Civilizations. Univeristy of California Press, Soil erosion and agricultural sustainability. Moss, B. Water pollution by agriculture. Pimentel, D. Environmental and economic costs of soil erosion and conservation benefits. Science , World agriculture and soil-erosion. Bioscience 37 , Price, T. School of American Research Press Schulze, D.
Soil Science Socity of America, Schwartz, G. The University of Arizona Press, Sharpley, A. Introduction: Agriculture as a potential source of water pollution. Agriculture, hydrology and water quality , Singer, M. Soils: An Introduction , 6th ed. Pearson Education Inc. Subbarao, G. Sodium - A functional plant nutrient. Critical Reviews in Plant Sciences 22 , , doi Tilman, D. Global environmental impacts of agricultural expansion: The need for sustainable and efficient practices. Agricultural sustainability and intensive production practices.
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Nature , , doi Trigger, B. Cambridge University Press, Troeh, F. Soils and Soil Fertility , 5th ed. Oxford University Press, Wakatsuki, T. Rates of weathering and soil formation. Geoderma 52 , Soil: The Foundation of Agriculture. What Are Soils? Food Safety and Food Security. Introduction to the Sorption of Chemical Constituents in Soils. Pests and Pollinators. Soil erosion controls on biogeochemical cycling of carbon and nitrogen.
The Influence of Soils on Human Health. Use and Impact of Bt Maize. Aquaculture: Challenges and Promise. Soil Carbon Storage.
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Soil Minerals and Plant Nutrition. Soil Water Dynamics. The Conservation of Cultivated Plants. The Soil Biota. Transgenic Animals in Agriculture. Throughout human history, our relationship with the soil has affected our ability to cultivate crops and influenced the success of civilizations. This relationship between humans, the earth, and food sources affirms soil as the foundation of agriculture.
Aa Aa Aa. Plant Nutrients. Soils for Agriculture. Inorganic Soil Components. As one might expect, contributions from each mineral size fraction help to provide the physical framework for a productive soil. Loamy-textured soils are commonly described as medium textured with functionally-equal contributions of sand, silt, and clay.
These medium-textured soils are often considered ideal for agriculture as they are easily cultivated by farmers and can be highly productive for crop growth. Due to their high surface area, clay particles can exert a large influence on various soil properties e. Clay minerals are colloidal particles, having high surface area, with charged surfaces; permitting binding of many essential plant nutrients.
The most prevalent clay-sized particles in soils fall into the class of layer-type aluminosilicates Sposito that commonly have permanent negative charge with a high CEC. Positively charged clay particles, which bind anions, include those which have pH dependent charge. The most common classes of these minerals in soils are the iron Fe , aluminum Al , and manganese Mn hydr oxides Schulze Soil pH.
Soil Degradation and Crop Production Soil forms from fresh parent material through various chemical and physical weathering processes and SOM is incorporated into soil through decomposition of plant residues and other biomass. Although these natural soil building processes regenerate the soil, the rate of soil formation is very slow. For this reason, soil should be considered a nonrenewable resource to be conserved with care for generations to come.
The rate of soil formation is hard to determine and highly variable, based on the five factors of soil formation. Scientists have calculated that 0. Because of the time required to generate new soil, it is imperative that agricultural practices utilize best management practices BMPs to prevent soil erosion. The soil which is first eroded is typically the organic and nutrient enriched surface layer which is highly beneficial for plant growth.
Thus, the primary on-site outcome is reduced crop yield as only the less fertile subsurface layers remain. Soil erosion also pollutes adjacent streams and waterways with sediment, nutrients, and agrochemicals creating serious off-site impacts. Table 2: Rates of soil erosion and net formation for various land use classes.
References and Recommended Reading Alexandratos, N. Diamond, J. Norton, Harlan, J. Crops and Man. Havlin, J. Soil Fertility and Fertilizers. Jenny, H. Factors of Soil Formation. McGraw-Hill, Pyne, S. Fire: A Brief History. University of Washington Press, Smith, B. The Emergence of Agriculture. Scientific American Library, Sparks, D.
Environmental Soil Chemistry. Academic Press, Inc. Sposito, G. The Chemsitry of Soils , 2nd ed. Wrangham, R. Basic Books, Keywords Keywords for this Article. Flag Inappropriate The Content is: Objectionable. Email your Friend.
Origins of food crops connect countries worldwide
This content is currently under construction. Explore This Subject. No topic rooms are there. Parikh Soil, Agriculture, and Agricultural Biotechnology. Other Topic Rooms Ecology. As a human he understands the desire to fight for the survival of humanity as an independent race. As an Oankali he understands that the combination of the species is necessary and that humans would destroy themselves again if left alone. Akin is kidnapped by the resisters as an infant, when the only evidence of his construct status is a tentacle-like tongue through which he samples his world in the Oankali manner of identifying DNA.
The Oankali allow the resisters to keep him for a sustained period of time so that he might understand his human nature more fully, but at the cost of the connection to his paired sibling that would have happened had he stayed with his family. His isolation is hugely painful to them both, and he is taken to the orbiting ship to experience whatever healing he and his insufficiently-paired sibling can be granted. Through these experiences, he realizes that humans, too, need an Akjai group, and his conviction ultimately persuades the Oankali.
Humans will be given Mars, modified sufficiently to barely support human existence, despite the Oankali certainty that the Mars colony will destroy itself eventually. Akin returns to tell the resisters and begin gathering them up to have their fertility restored before transport to their new world. The final book of the trilogy, Imago , is the shortest. Imago shows the reader what has been hinted at for the last two books: the full potential of the new human-Oankali hybrid species. The story is in the first person from the perspective of Jodahs, the first Ooloi construct and a child of Lilith.
Through its unique heritage it has unlocked latent genetic potential of humans and Oankali. Imago brings a sense of completeness to the three books, by allowing the reader to understand the Oankali better by understanding Jodahs. Jodahs also builds upon Lilith and Akin's human-Oankali integration work from the previous two novels; the novel ends with the humans more willingly acquiescing to the Oankali.
Throughout the Xenogenesis trilogy themes of sexuality, gender, race, and species are explored. The Oankali believe that the human species have an inevitably self-destructive "Contradiction" between their high intelligence and their hierarchical natures. According to the Oankali this is what caused the war that almost ended the human race, and this is why they cannot leave the humans alone.
Lilith and the Oankali-human hybrids are constantly battling with this inner conflict. According to Tor. The human-Oankali hybrids feel that they have somehow betrayed their human side by integrating into Oankali society, but at the same time, because of the vast power imbalance, they never really had another viable option.
Sex at dawn : the prehistoric origins of modern sexuality
In addition to allegorizing slavery, the trilogy more generally is written "in the context of colonization,"  as Nelson puts it, raising broad questions of coercion and agency. The relationship between the Oankali and the humans speaks to a range of imperialist relationships, from slavery to internment camps  to eugenics. The series also draws upon elements of the myth of Lilith , the first wife of Adam.
In addition to the social themes, the possible results of developing genetic science and biologically based technology are shown by the Oankali's genetic mastery.
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Joan Slonczewski , a biologist, published a review of the series in which she discusses the biological implications of the ooloi and how they can, through genetic engineering, achieve positive effects from "bad" genes such as a predisposition for cancer. Orson Scott Card commends the Xenogenesis trilogy as "more satisfying as hard science fiction" than Butler's earlier Patternist novels, specifically in that they show "how much power her storytelling has gained" in the intervening years.
In terms of each novel, Adele Newson praises the prose of Dawn, as "engaging" and having "a single-minded intensity. In contrast, Newson finds the story's development in Adulthood Rites "disappointing": Lilith, she points out, "does little more than sulk silently away" and the story relies so much on "laborious" dialogue that it becomes "more or less a treatise in on the contradictory and often violent nature of humankind. Each of the three novels originally was nominated for the Locus Award for Best Science Fiction Novel in the year it was published , , and , though none of the books won the award.
In September , it was announced that producer Allen Bain had optioned the rights to make Dawn for television. Ackerman, Erin M. From Wikipedia, the free encyclopedia. Lilith's Brood. Grand Central Publishing. Retrieved Retrieved 24 November Archived from the original on 28 August This audio file was created from a revision of the article " Lilith's Brood " dated , and does not reflect subsequent edits to the article. Audio help. More spoken articles. Works by Octavia Butler.
Dawn Adulthood Rites Imago.