ENVS Chapter 13: Agriculture and the Ecology of Food
gravity water
water that flows through the soil as it percolates into the soil and is drawn downward by the force of gravity
hygroscopic water
water that is bound to soil particles and cannot be easily used by plants
capillary water
water that is held in the soil bu water-to-water hydrogen bonds
A horizon
A layer of soil containing a mixture of organic manner and mineral particles
broad-spectrum pesticide
A pesticide that kills a wide variety of organisms
transpiration
The action of water evaporating from leaves
field capacity
The amount of water that a given volume or weight of soil and hold against the force of gravity
integrated pest management (IPM)
The effective combination of all three kinds of pest control- chemical, biological, and cultural- carefully designed to minimize environmental damage
harvest index
The fraction of total production that can be used by people
C horizon
The lowest layer of soil or weathering zone
biological magnification
The process by which the concentration of the chemicals such as DDT or mercury increases through a food chain also called biomagnification
drip irrigation
The system that provides water to plants through pipes with small openings at the base of each plant that feed water to the root zone
O horizon
The top layer of natural soil consisting of humus
agroecosystem
crops and domestic animals, the physical environments in which they grow, and the communities of other organisms associated with them
humus
leaves or crop residue and the organic products of their decomposition
trophic-level efficiency
the fraction of energy that the organisms in one trophic level store as biomass and make available to the next trophic level
Green Revolution
the period since 1950 during which global agriculture productivity increased many times over
agronomy
the science that applies the knowledge from other fields of study such as genetics, physiology, chemistry, and ecology to agriculture
B horizon
the subsoil below A horizon that is especially rich in clay particles that form from minerals dissolved from the weathering of sand and silt
agriculture
the system of land management used to grow domesticated plants and animals for food, fiber, or energy
soil
the uppermost layer of the Earth's crust that supports plant growth; a mixture of organic matter and mineral particles
biological pest control
the use of predators and parasites to manage pests
soil fertility
the variety of soil characteristics that support plant growth
