Page 636 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

THEhumanDENOMINATOR 18 Soils and Land Use
SOILS HUMANS HUMANS SOILS
• Soils are the foundation of basic ecosystem function and are a critical • Humans have modified soils through agricultural activities. Recently, resource for agriculture. fertilizer use, nutrient depletion, and salinization have increased soil
• Soils store carbon dioxide and other greenhouse gases in soil organic matter. degradation.
18a
Grapevines grow in the soils of Lanzarote in the Canary Islands, producing wines from the fertile black ash of some of the most isolated vineyards in the world. Stone walls protect plants from the Atlantic winds.
[Raul Mateos Fotografia/Getty Images.]
• Poor land-use practices are combining with changing climate to cause desertification, soil erosion, and the loss of prime farmland.
18b
Nigerian women dig a trench to collect rainwater in the Sahel region of Africa. Although above-average rainfall in 2012 led to a successful harvest, the effects of desertification are ongoing throughout the region. [ISSOUF SANOGO/Getty Images.]
18d
Soybean fields are readied for planting in Mato Grosso state, Brazil, where vast tracts of rain forest are being cleared for industrial agriculture. Oxisols, the soils of the tropics, have low fertility, requiring the use of fertilizers, which along with pesticides are affecting water quality throughout the region. [Latin Content/Getty Images.]
18c
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ISSUES FOR THE 21ST CENTURY
Desiccation of the Aral Sea began when rivers were diverted to irrigate cotton fields. The shrinking lake has accelerated desertification in the Aral basin of Kazakhstan and Uzbekistan, and affected the local climate, which is now hotter in summer without the moderating influence of the former large water body. [USGS EROS Data Center.]
• Continued soil erosion and degradation will cause lowered agricultural productivity worldwide and possible food shortages.
• Thawing of frozen soils in the northern latitudes emits carbon dioxide and methane into the atmosphere, creating a positive feedback loop that leads to further warming.
• Increased use of sustainable soil management and land use practices will improve soil quality and agriculture.
• Global water availability and quality issues will have widespread impacts on agriculture and soils.
geosystemsconnection
Soil science forms the bridge between Parts i, ii, and iii, which cover the abiotic systems, and Part iV, which explores the biotic systems of Earth. Soil formation is affected by temperature, moisture, parent material, topography, and living organisms, including humans. Thus, this chapter combines aspects of the energy–atmosphere and the water, weather, and climate systems, as well as of the weathering processes that are the source for soil particles and minerals, into a study of the soils that cover Earth’s surface. Next, we move to the essential components of Earth’s ecosystems, and from there to the biotic operations that fuel living systems and the communities that organize life.
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