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Chapter 7 ENV Review

Chapter 7 ENV Review - Chapter 7 Soil Agriculture and the...

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Chapter 7 Soil, Agriculture, and the Future of Food Soil is the foundation for agriculture Land devoted to agriculture covers 38% of Earth’s land surface Agriculture Practice of raising crops and livestock for human use and consumption Cropland Land used to raise plants for human use Rangeland or pasture Land used for grazing livestock Traditional agriculture Uses human and animal muscle power, hand tools, and simple machines Industrialized agriculture Uses large-scale mechanization and fossil fuels to boost yields. It also uses pesticides, irrigation, and fertilizers Poorly managed agriculture Turns grasslands into deserts Removes forests Diminishes biodiversity Pollutes soil, air, and water Fertile soil can be Blown and washed away Land suitable for farming is Running out Soil A plant-supporting system consisting of water, disintegrated rock, organic matter, gases, nutrients, and microorganisms Animals in soil Bacteria, algae, earthworms, and insects 1 teaspoon of soil can Contain 100 million bacteria, ½ million fungie, 100,000 algae, and 50,000 protists Soil profiles comprise horizon Soil profile Entire cross-section of soil Amount of organic matter decreases Downward Top soil (A horizon) Layer that is most nutritive for plants Leaching Solid particles are dissolved and move elsewhere (down through horizons) Topsoil Is vital for agriculture
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Unsustainable practices Deplete organic material and reduce the soil’s fertility and ability to hold water Soil scientists classify soils using Color, texture, structure, and pH The soil most suitable for agriculture is Loamy mixture with a pH close to neutral that is workable and can hold nutrients Tropical rainforest soils Are much less productive than temperate grasslands Frequent rain leaches Minerals and nutrients, reducing their plants Swidden agriculture “shifting cultivation” Cultivating a plot of land for a few years and moving elsewhere Temperate grasslands have Lower rainfall and less leaching. Nutrients remain within reach of plant roots In tem grasslands soils can be Repeatedly farmed with appropriate techniques Most of the world’s soils are not ideal for agriculture but With human population growth, humans are forced to cultivate more unsuitable lands Poor agriculture practices reduce Soil’s ability to support life Over the past 50 years, soil degradation has Reduced global crop, yields by 13% on cropland Soil degradation results from cropland, agriculture, deforestation, and overgrazing Erosion Removal of material from one place to another by wind or water Deposition Arrival of eroded material at a new location Erosion and deposition are natural processes that in the long run can help the soil like Flowing water that deposits sediment in river valleys and deltas. This is why floodplains are excellent for farming
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Chapter 7 ENV Review - Chapter 7 Soil Agriculture and the...

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