117 terms

Chapter 9

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Tilling:
plowing, disking, harrowing, or chiseling the soil. Aerates soil and works weeds and old crop residue into the soil to nourish it, but leaves the soil bare allowing wind and water to erode away topsoil.
No-till farming
rather than plowing after each harvest you leave crop residues atop of fields keeping the soil covered in plant material at all times. To plant next crop you cut a thin shallow groove into the soils surface, drop in seeds, and cover them. Less soil erodes, organic material accumulates, and soil soaks up more water all of which encourages better plant growth. Saves fuel, time, effort, and wear and tear on the equipment.
Cover Crops
crops planted to hold the soil in place between times that main food crops are growing. I.e. Rye grass seeds that prevent erosion when corn and soy beans are not growing and makes planting easier by loosening the soil structure. Recycle nutrients and may reduce fertilizer use.
Conservation Measures
No Till farming, Cover Crops, taking soil sample to determine fertilizer usage, growing grass borders to keep soil and nutrients in, installing a bioreactor an underground container full of carbon rich woodchips to filter out excess nitrogen so it does not pollute ground water.
Agriculture:
the practice of raising crops and livestock for human use and consumption. (Most food and fiber comes from cropland and rangeland) Land devoted to _______ covers 38% of Earth's land
Cropland
Land used to raise plants for human use feed most of human population Covers 12% of earth's surface.
Rangeland:
Pasture of land used for grazing livestock. Covers 26% of earth's surface
Healthy Soil
Provide nutrients. Have a structure that allows roots to penetrate deeply. Retain water
Soil
a complex system of disintegrated rock, organic matter, water, gasses, nutrients such nitrogen and phosphorus that enable plant growth, and microorganisms.
soil structure and texture
influence root penetration and growth
H20 and soil
soils that retain the right amount of this but drain excess make the perfect amount for plants to grow.
Organic matter
provides nutrients and helps with structure and water retention.
Sustainable Agricultur
Healthy soil is a key component of this. Allows soil to renew its nutrients content and retain its character from one crop to the next. Also requires clean water, minimized use of fossil fuel based fertilizers and pesticides, healthy populations of pollinating insects, sustenance of genetic diversity, and genetic modification.
10,000
agriculture arose _________ years ago.
Selective Breeding
intentionally planting seeds from plants whose produce was most desirable. Artificial made from wild plants or animals. Started by our ancestors and has produced many hundreds of crops we enjoy today.
Fertile Crescent
one of five independent areas that started raising and domesticating plants and animals. Located in the Middle East. Possibly earliest found area 10,500 years ago. Wheat, barley, rye, peas, lentils, onions, garlic, carrots, grapes, and other crops originated here. As did goats and sheep. Earliest.
Positive feedback cycle:
Planting crops made people stay. People staying inspired more crops.
Soils ingredients:
5% organic matter, 50% mineral matter, and the rest consists of pore space taken up with air or water
Traditional Agriculture
biologically powered form of agriculture that uses human and animal muscle power. Hand tools, simple machines. Uses Polycultures and subsistence agriculture.
subsistence agriculture.
form of agriculture in which families produce only enough food for themselves
Polycultures
different crops are planted in one field
Industrial Agriculture
form of agriculture that uses large-scale mechanization and fossil fuels to boost yields. (dominates today)
Also uses pesticides, irrigation, and fertilizers and monoculture.
Monoculture
uniform planting of a single crop
Green Revolution
new technology, crop varieties, and farming practices were introduced to developing countries
Increased yields and decreased starvation
Degraded the integrity of the soil
Organic matter ingredients
includes living and dead microorganisms as well as decaying material derived of plants and animals.
Bacteria & fungi algae and protists:
A teaspoon of soil can contain millions of _____ and thousands of ____, _____, & ______.
An ecosystem:
Soil is a/an _______ because of being composed of living and nonliving organisms that interact in complex ways.
Terrestrial primary succession:
succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited. Begins with lithosphere being exposed to the effects of the atmosphere, hydrosphere, and biosphere.
Parent Material:
is the base of geologic material in a particular location. I.E. Hardened lava or organic ash, rock or sediment deposited by glaciers, wind-blown dunes, sediments deposited by river, or bedrock.
Weathering
processes that break large rock particles down into smaller ones Physical, chemical, or biological
Physical (mechanical) weathering
wind and rain; no chemical changes in the parent material
Chemical Weathering
parent material is chemically changed
Biological Weathering
organisms produce soil through physical or chemical means
Humus
spongy material formed by partial decomposition of organic matter; holds moisture. Provides nutrients. holds micro organisms that break down plant waste.
5 major components of soil formation
Climate, organisms, topography, parent material, and time.
Climate
soils form faster in warm, wet climates
Organisms
plants and decomposers add organic matter
Topography
hills and valleys affect exposure to sun, wind, and water
Parent material
influences properties of resulting soil
Time
soil can take decades to millennia to form
Soil Profile
the cross-section of soil as a whole. Degree of weathering and amount of organic matter decrease in lower horizons. composed of 6 horizons that create distinct layers based on their composition from surface to bedrock.
Horizon
each different layer of soil. IN ORDER: o, a, e, b, c, r. Degree of weathering and concentration of organic matter decrease as you move down this ______.
A, B & C horizon:
correspond respectively to topsoil(____), subsoil (_____), and weather parent material (_____)
E Horizon:
Eluviated (Leaching layer)
O Horizon:
organic material or leaf litter.
Top soil horizon A
inorganic and organic material most nutritive for plants
Vital for agriculture
B horizon
Subsoil where leaching brings down minerals where they accumulate
C Horizon:
is weathered parent material. Most nutritious for plants and takes its loose texture, dark coloration, an strong water holding capacity from humus.
Leaching
Transports minerals downward. The process whereby solid particles suspended or dissolved in liquid are transported to another location. Like coffee grinds in a drip filter.
Minerals commonly leached:
From e horizon include iron, aluminum, and silicate clay
Soil Classification
based on properties such as color, texture, structure, and PH.
Soil Color
Black or dark brown soils are usually rich in organic matter whereas a pale color often indicates leaching or low organic content.
Soil texture
Determined by size of particles. Broken down into Clay, sand, silt, and loam.
Clay
consists of particles less than .002 mm in diameter. Sticky feeling when moist. Adheres very well. Make difficult for water and air to pass through because compacted together.
Silt
.002-.05mm in diameter. Balance of adhere. Feels powdery when dry and smooth when wet. Best for plant growth.
Sand
05-2 mm in diameter. Does not stick together or adhere to one another. Porous and allow water to pass through quickly. Require frequent irrigation.
Loam
an even mixture of sand, silt, and clay particle sizes. Best for plant growth. Affects how easily air and water travel through the soil. Influences how easy soil is to cultivate
Soil Structure
is a measure of soil's "clumpiness". A medium amount of clumpiness is best for plants. Repeated tilling compacts soil, decreasing its water-absorbing capabilities
Soil PH
plants can die in soils that are too acidic or too alkaline. Intermediate values best for plant growth. 8, 7, & .influences the availability of nutrients for plants
I.e during leaching acids from organic matter may remove nutrients from the site of exchange.
Cation Exchange
plants gain many nutrients through this process. Plant roots donate hydrogen ions to the soil in exchange for nutrient ions which the soil particles then replenish by exchange with water.
Cation
Soil particle surfaces that are negatively charged hold _____ or positively charged ions such as those of calcium, magnesium, and potassium.
Cation exchange capacity:
expresses soils ability to hold cations ad prevent them from leaching (thus making them available for the plants.) Useful measure of soil fertility.Decreases with lower pH High ____________= soils with fine textures and rich in organic matter. Lower PH (more acidic) = Lower ___________.
Cation exchange capacity
Cations that don't leach are more available to plants
A useful measure of soil fertility. Greatest in fine textured or richly organic soils
Sweden Agriculture
farmers cultivate plat for one to a few years and then moves on to clear another plot leaving the first to grow back to forest. (done in tropical rainforest due to low soil fertility)
Farming or grazing on unsuitable lands:
turns grass land into deserts, remove forests, diminish biodiversity, encourage invasive species, pollute soil/air/ water with toxic chemicals, and allow fertile soil to be blown away.
Soil degradation:
Common in drier regions. Soils deteriorate in quality and decline in productivity. Results primarily from forest removal, cropland agriculture, and overgrazing livestock. Has reduced rates of food production by 13% in cropland and 4% in rangeland.
Land degradation:
deterioration of land that diminishes productivity and biodiversity, impairs the functioning of its ecosystems, and reduces the ecosystem services it offers us. Caused by unsustainable agriculture, deforestation, and urban development. Soil erosion, nutrient depletion, water scarcity, salinization.
Erosion:
is the removal of material from one place and its transport toward another by action of wind or water. Tends to happen more quickly than soil is formed. Removes topsoil
Deposition:
occurs when eroded material is deposited at a new location. Flowing water deposits nutrient-rich sediment in river valleys and deltas. Floodplains are excellent for farming
Peoples negative impacts on erosion:
over cultivating fields through poor planning and excessive tilling, grazing rangeland with more livestock than the land can support, and clearing forest on steep slopes or with large clear cuts.
Drylands
arid and semi-arid environments that cover about 40% of the earth's land surface. Much of the world's population live and farms here. Most Prone to desertification.
Wind erosion
Windy regions with sparse plant cover suffer from
Water Erosion
Areas with steep slopes, high precipitation, and little plant cover suffer from
Desertification
describes a form of land degradation in which more than 10% of productivity is lost as a result of erosion (most due to this), soil compaction, forest removal, overgrazing, drought, salinization, climate change, water depletion, and other factors. Made worse by climate change.
Soil erosion
Physical barriers to capture soil can prevent it. Plants slow wind and water flow. Roots hold soil in place
No-till agriculture leaves plant residue on fields
Cover crops protect soil between crop plantings
5
U.S. farmlands lose ___ tons of soil for each ton of grain harvested
Soil conservation act of 1935:
established Soil Conservation Service (SCS) an agency that worked closely with farmers to develop conservation plans for individual farms using science to assess the land's resources and problems, and collaboration with landowners.
Teams formed by SCS
soil scientists, forestry experts, engineers, economists, and biologists
Conservation Districts
districts that promote soil conservation practices at the county level. Operate with federal direction, authorization, and funding and are organized by the states
Natural resources conservation service (NRCS):
what SCS changed to. Responsibilities added to include protection of water quality and pollution control.
Agriculture extension agents:
experts who assist farmers by providing information on new research and by helping them apply this knowledge with new techniques. Provided by state universities.
Ways to protect soil in agriculture:
Crop rotation, contour farming, terracing, intercropping, shelterbelts, conservation tillage.
Crop rotation:
farmers alternate the type of crop grown in a given field from one season or year to the next. Returns nutrients to the soil, minimizes erosion from letting fields lie fallow, and can break cycles of disease associated with continuous cropping. Reduces insects or pests by not letting them get used to a certain type of crop.
Contour Farming
plowing furrows sideways across a hillside perpendicular to its slope. Sides of furrows trap water and prevent erosion.
Terracing
cutting level platforms into steep hillsides
The steps of this "staircase" hold water
Intercropping:
planting different crops in alternating bands or other spatially mixed arrangements. Helps slow erosion by providing more ground cover that does a single crop. Increases ground cover, preventing erosion. Decreases pests and disease. Replenishes soil
Shelterbelts:
AKA Windbreaks rows of trees or tall shrubs to slow wind.
Conservation tillage
describes an array of approaches that reduce the amount of tilling relative to farming. One way is leaving 30% of crop residue covering soil after harvest.
No Till benefits
carbon storage, burns less gasoline. It increases organic matter and soil biota. Reduces erosion and improves soil quality. Uses less labor, saves time, causes less wear on machinery. Adds organic matter to soils that is kept from the atmosphere
No till difficulties
Needs for more chemical herbicides due to less weed removal, and synthetic fertilizer.
Green manure:
dead plants as fertilizer.
Positive feedback loop
soil erosion makes it difficult for vegetation to regrow the problem continues because of lack of cover and gives rise to more erosion.
"Tragedy of the commons":
traditionally ranchers have had no incentive to conserve rangelands because most grazing has taken place on public lands leased by the government and tax payers have heavily subsidized grazing.
Meta-Analysis:
statistical analysis of numerous studies.
Irrigation
The artificial provision of water beyond that crops receive from rainfall. I.e. rice and cotton need a lot more water and beans and wheat require very little.
keep the plant cover in place
Farming methods to reduce erosion have one goal
$23 billion
Degraded rangeland costs over _____ worldwide
70%
:_____ of fresh water that people withdraw is used for irrigation. Which has depleted aquifers and dried up rivers and lakes.
Drip irrigation
: hoses drip water directly onto plants so that much less is wasted. Makes plants use 90% of water provided. Other irrigation methods use 43%
Waterlogging:
occurs with overirrigated soils saturated with water. When water table rises to the point that water drowns plant roots depriving them access to gases and suffocating them.
Salinization:
the buildup of salts in surface soil layers. Due to evaporation in more arid climates and water containing and pulling up salts to horizon a layer. Water dries leaving behind salt residue. Inhibits crop production on 1/5 of irrigated cropland globally. Expensive to fix.
Prevent salinization:
avoid planting crops that need a lot of water in areas prone to salinization. Irrigate with water low in salt content. Supply no more water than a crop needs.
Repair salinization:
stop irrigating and wait for rain to flush salts from soil, plant salt tolerant plants, or bring in large quantities of less-saline water to flush soil but could cause waterlogging.
Inorganic fertilizers
are mined or synthetically manufactured mineral supplements.
Fertilizer
substances that contain essential nutrients such as nitrogen phosphorus, and potassium.
Inorganic fertilizers impacts:
More susceptible to leaching and runoff and more readily contaminate groundwater supplies. Nitrogen and phosphorus runoff spurs phytoplankton blooms in gulf and creates oxygen depleted dead zones that kills fish. Nitrates leach through soil and contaminate ground water.
Human health risks inorganic fertilizers:
cancer and methemoglobemia, blue baby syndrome,
Organic fertilizers:
consist of remains or wastes of organism and include animal manure, crop residues; fresh vegetation (green manure) and compost.Improving soil structure. Increasing nutrient-holding capacity. Increasing water-retaining capacity.
Compost:
a mixture produced when decomposers break down organic matter such as food and crop wants in a controlled environment.
Wetlands reserve program:
the us government offer payments to those who help restore and enhance wetlands
Farm Bill:
funded 15 programs (including wetlands reserve program) to encourage the conservation of soil, grasslands, wetlands, wildlife habitat, and other natural processes on agriculture lands. Received 9% of budget.
Conservation Reserve Program:
pays farmers to stop cultivating damaged and highly erodible crop land and instead make these lands conservation reserves planted with grasses and trees. Each dollar invested in the program saves 1 ton of top soil. Also generates income for farmers, improves water quality, and provides habitats for wildlife.
Bureau of land management:
Most of the range land is owned by...
Biggest problems of agriculture
: moving from polyculture to monoculture. Because one crop attracts more pests.
Wetlands
swamps, marshes, bogs, river floodplains
Over 50% have been drained for agriculture in the U.S.
Swamp Lands Acts (1849, 1950, 1860) =
drained and converted wetlands to control floods and malaria
The Food and Agriculture Organization (FAO)
is the United Nations' main agricultural program. Supports innovative approaches to resource management and sustainable agriculture in Asia
Helps farmers duplicate agricultural success stories
Uses local communities to educate and encourage farmers to conserve soils and secure the food supply
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