the relatively thin surface layer of the Earth's crust consisting of mineral and organic matter modified by the natural actions of agents such as weather, wind, water, and organisms
a region's surface features
partly decomposed organic material in the soil; brown or black in color; binds nutrient mineral ions and holds water and persists in agricultural soil for about 20 years
removal of dissolved material from the soil by water percolating downward
the deposition of leached material in the lower layers of soil
the uppermost layer of soil rich in organic material. Plant litter accumulates in this layer.
beneath the O-horizon, is dark and rich in accumulated organic matter and humus. Has a granular texture and is somewhat nutrient poor due to leaching. The nutrients lost enter the deeper layers
a heavily leached layer
light-colored subsoil, often a zone of Illuviation in which nutrient minerals that leach out of the topsoil and litter accumulate
contains weathered pieces of rock and borders the unweathered solid parent material
bits of soil that have passed through the gut of an earthworm
associations between fungi and the roots of vascular plants enabling plants to absorb adequate amounts of essential nutrient minerals from the soil
the threadlike body of the fungi partner which extends into the soil beyond the roots
the pathways of various nutrient minerals or elements from the environment through organisms and back to the environment
a mixture of different-sized particles to create the ideal agricultural soil; approximately 40% sand, 40% silt, and 20% clay. The larger particles provide structural support, aeration, and permeability to the soil, whereas the smaller particles bind together into aggregates and hold nutrient minerals and water.
usually forms under a coniferous forest and had an O-horizon of acidic liter; an ash-gray, acidic, leached E-horizon; and a dark brown; illuvial B-horizon rich in organic matter and aluminum and iron oxides
usually forms under a temperate deciduous forest, fertility is maintained by plant litter, precipitation is great enough to wash away clay and nutrient minerals from the A and E horizons into the B-horizons
found primary in temperate semiarid grasslands. Very fertile. Possesses a think, dark brown to black A-horizon that is rich in humus. Precipitation is not great enough to leach nutrients into lower layers.
found in arid regions of all continents. Lack of precipitation precludes much leaching and the lack of lush vegetation precludes the accumulation of much organic matter. Lack distinct layers of leaching and illuviation.
low in nutrient minerals, exist in tropical and subtropical areas with ample precipitation. A-horizon is enriched with humus derived from decaying plants. The B-horizon is thick, highly leached, acidic and nutrient poor.
Sustainable soil use
use of soil resources wisely, without a reduction in the amount or fertility of soil, so that it is productive for future generations
residues from previous crops are left in the soil partially covering it and helping it hold it's place
leaves the soil undisturbed over the winter
the planting of a series of different crops in the same field over a period of years
field are plowed and planted in curves that conform to the natural contours of the land
a special type of contour plowing, produces alternating strips of different crops along natural contours
produces level areas and reduces soil erosion
includes natural materials, are chemically complex and their exact compositions vary
are available to plants only as the organic material decomposes
Compound Inorganic Fertilizer
manufactured from chemical compounds and their exact composition is known
they are soluble and immediately available to plants but are available in the soil only for a short period of time
rows of trees that lessen the impact of wind on soil
Soil Conservation Act of 1935
authorized the formation of the Soil Conservation Service (now the Natural Resources Conservation Service); its mission to work with U.S. citizens to conserve natural resources on private lands
Food Security Act (Farm Bill) of 1985
creates a conservation compliance program and the Conservation Reserve Program
Conservation Reserve Program (CRP)
a voluntary program that pays farmers (about $10 per acre) to stop producing crops on highly erodible farmland