IBESS Unit 5 Study Guide

5.1 Introduction to Soil Systems | 5.2 Terrestrial Food Production Systems and Food Choices | 5.3 Soil Degradation and Conservation

soil

soil

mixture of minerals, organic matter, water & air

4 primary functions of soil

1. medium for plant growth with water and nutrients

2. major water storage/purification system

3. habitat for ¼ soil-modifying species

4. modify atmosphere via respiration/roots

“sphere classifications”

• soil → pedosphere

• water → hydrosphere

• rock → lithosphere

• air → atmosphere

• living → biosphere

parent material

soil origin materials

• turn into soil via weathering

weathering

process of rocks changing into soil

soil differentiation factors

• climate - changes in precip/evap/temp

  • water freezing/thawing has higher

• relief/topography - less slanted/slop → better soil

  • flat land → stationary rocks → good agricultural soil

• organisms - primary succession on rocks → rock breakdown

• time - soil is a non-renewable resource due to the fact recovery time > human lifespan

reasons why soil is an ecosystem

living organisms classify soil as ecosystem

reasons why soil is a system

• 6 critical components

  • water - for weather/soil texture

  • organic matter - DOM and basic elements

  • organisms. - add nutrients

  • minerals - parent material

  • air - weather and the porosity/permeability of soil

  • nutrients. - found in OM

3 categories of soil

• clay (finest)

• silt

• sand (coarsest)

loam

best agricultural soil; best combo of sand, silt & clay

clay effects on soil

• increase in turbidity → no water absorbed

• mineral/nutrient storage

  • negative clay attracts positive particles (metals ions: calcium/potassium)

humus

decomposing organic matter found in soil layers

soil profile/horizons

• O-horizon - top layer with loam

• A-horizon - lot of topsoil and loam

• E-horizon - leached layer

• B-horizon - subsoil without humus

• C-horizon - accumulation zone

  • where metals/nutrients from previous leeching lay

• R-horizon - parent material

erosion

movement of soil from one place to another via wind or water

wind erosion

wind picking up soil particles & carrying them away

water erosion

• detachment - raindrops hit soil → freed soil particles

• transport - water flow carries particles

• deposition - water slows → particles deposited

sheet erosion

fairly thin layer of soil removed by run-off

gully erosion

water erosion creating deep channels

chemical degradation

• salinization - leftover salts from water evap → saline soil

  • common with high temps and high irrigation

• acidification - high hydrogen ions concen → lowered pH

  • caused by acid deposition, leeching, or nutrient removal

• nutrient depletion - loss of nutrients via over-exploitation

• chemical depletion - accumulation of toxic metals within soils from pesticides

physical degradation

• compacted soil due to heavy machinery/animals

• water infiltrating rock and freezing → cracked rock

Wangari Maathai

Kenyan black female who won 2004 Nobel Peace Prize for planting trees

• way of replenishing the wood lost of deforestation

• worked with gov’t to cancel school to plant trees

arable farms

farms with crops (ie. corn)

pastoral farms

farms that rear animals

mixed farms

farms with crops and animals

intensive comerical farming

intensive farming with high labor and high yield

• usually uses GMOs, fertilizers, pesticides, herbicides, insecticides, and mechanical technologies

battery farming

term to describe animals kept in close quarters

• higher risk of spreading diseases (ie. bird flue)

subsistence farming

farming based on providing enough for family and leftover for selling

• areas without supermarkets rely on this (parts of Asia)

monoculture farming

farming with one crop at a time

• ie. coffee plants in tropicals

• usually cash crops: crops used as financial outlets; usually sold in local shops

crop rotation

shift/schedule of crops to stop nutrient depletion

• not available to LEDC/subsistence farmers

cover crop

crops used to cover open soil

ie. sweet clover used to fixate nitrogen to soil; also used as humus

nomadic farming

movement with animals in search of suitable grazing areas

ie. Maasai in Africa herd cattle for meat, milk, and blood

shifting agriculture

method of farming with clearing land and farming for some years then moving and repeating

• usually in tropical rainforests with slash-and-burn method

• sustainable for low pops, high pops → low crop yields, high soil damage

organic farming

farming with prohibited use of growth hormones/GMOs (genetically-modified organisms), synthetic fertilizers (MiracleGro), synthetic pesticides (neonicotinoids, DDTs)

• high priced crops with low yields limits availability by socioeconomic class

food waste breakdown by HDI

• HEDCs have high food waste at consumption

• LEDCs have high food waste at packaging/storage

demand for meat reasons

• population growth

• affluence equal to addorability

• urbanization

• cultural value

• cheap meat value

• proteins in meat

processes/causes of soil degradation

• urbanization

• grazing livestock

• deforestation

• farming methods

• salinization

• clear cutting

furrows

little dips within ground so you can walk/have irrigation

• can cause water run-off if not flat

tillage

ploughing land and clearing debris

• leads to bare and erosion-vulnerable soil

tilled land

tilling of land which causes cloudy air from soil kickup

no-till

untilled land allowing for crop protection against natural events

GHGs in Farming

• Methane (MH4)

  • rice flooding → anaerobic decomp

  • compacted/waterlogged compost → decreased oxygen

  • cow anaerobic consumption → flagellate

  • less oxygen with fires

• Carbon Dioxide (CO2)

  • any fires

• Nitrous Oxide (N2O)

  • fertilizers overpowering soil

biochar

black carbon created by humans converting wood C to charcoal C

anaerobic digestors

storage area for farmers to put cow manure

• creates methane which is converted into electrical energy for farm

• decreases amount of manure in rivers, waters, etc.

silt fences

barriers of silt and sand

• allows clay and water with fences’ pores

terraces

flat areas separated by walls

• walls prevent moving soil/water

• labor expensive

contour farming

circleline of crop soil on same elevation

• can be intensive with tech requirement

• basically circular furrows

strip cropping

alternating crops planted

• helps with nutrient depletion (crop rotation’s sister)

conservation tillage

when farmers leave crop reside on top as seeds are planted

• new crops grow via DOMs

• can act as mulch - residue left to conserve water and stop weeds

shelterbelts

line of trees/shrubs to prevent high wind velocities

agroforestry

crops alternating with trees to provide shade

• must use plants with low sunlight requirement

calcium carbonate (CaCO3)

limestone aka “lime” that neutralized carbonic acid (H2CO3) and stops pH drops

Community Supported Agriculture (CSA)

payment by consumer in advance of planting/harvesting season

-risk of farming assumed by consumer

can be risky due to crop seasonality

Land Use, Land Use, Change and Forestry (LULUCF)

changing of ecosystem → agricultural land

• 75% of deforestation due to agriculture

• Palm Oil agriculture is 11-15% of GHGs

  • used for cheapness/preservation

  • found in oreos, nutella, etc

  • endangers habitats (orangutans)

selective/artificial breeding

breeding of the “best” crops to feed the world

Norman Borlaug

person who bred wheat, rice and corn to save billions of lives from 30s-50s

• focused on monoculture w/ similar gene pool = high disease risk (ie. Bird Flu)