ess: chapter 5 - soil systems and society

subsistence agriculture

subsistence agriculture

no surplus, farmer produces for own use only. mixed crops, human labour, few fossil fuels and chemicals, vulnerable to food shortages

commercial agriculture

large, profit-making scale, monoculture of one crop or animal

extensive farming

uses more land but low density and low in-/outputs

intensive farming

high in-/output per unit area

pastoral

raising animals on land not for crops

arable

growing crops on good soil

mixed farming

both crops and animals in a system where animal waste → fertilise crops → some crops fed to animals

agribusiness

business of agricultural production

LEDC

less economically developed country, low industrialisation and GNP per capita. high population growth, low EF

MEDC

more economically developed country, high industrialisation and GNP per capita. low population growth, high EF

factors to consider when evaluating farming

• agribusiness

• scale of farming

• industrialisation

• mechanisation

• fossil fuel use

• seed/crop/livestock choices

• water use

• fertilisers

• antibiotics

• legislation

• pollinators

malnutrition

can be lacking (undernourished), excessive (over-nourishment), or unbalanced (wrong proportion of micro-nutrients)

cash cropping

food grown for export instead of being fed to indigenous population, often coffee, hemp, flax, biofuel

NIC

newly industrialised country, hard to define as either MEDC or LEDC, is on the rise in industrial development, GDP and civil rights

HDI

human development index; based on life expectancy, GDP per capita and education

fertility rate

how many children every couple adds to the population (2.0 = 2 kids, 2.5 = 3 kids)

reasons for having large families

1. high infant and child mortality (insurance of guaranteed survival)

2. security in old age (traditionally take care of parents when lacking welfare)

3. children are economic asset (in agricultural societies, not in MEDCs)

4. status of women (often considered worthy only for child-bearing ability)

5. unavailability of contraceptives

O Horizon

1: newly added organic material (eg. leafs)

A Horizon

2: humus layer with organic matter enrichment

B Horizon

3: mineral enrichment (iron, aluminium)

C Horizon

4: weathered rock from which the soil forms

R Horizon

5: bedrock, parent material

sandy soil

gritty, falls apart easily (biggest particles)

silty soil

feels slippery, holds together well (medium size particles)

clay soil

sticky, can be rolled up into a ball (smallest particles

loam soil

mix of sand, silt and clay, ideal for agriculture

porosity

amount of space between particles

permeability

the ease at which gases and liquids can pass through soil

NPK

nitrates, phosphates and potassium; the main soil nutrients, essential for healthy plant growth

factors that influence food choices

1. climate (local conditions)

2. cultural and religious

3. political (governments can subsidise to encourage/discourage (eg. EU))

4. socio-economic (supply and demand)

monoculture

one species crop in arable farming, with alterations for maximum growth rate

crop rotation

a way of addressing loss of soil fertility; planting legumes every 4th year (eg. soya beans, peas) to add nitrogen to soil

soil degradation

either due to

• processes that take away the soil (erosion), mainly when no vegetation

• processes that make the soil less suitable for use, various chemicals end up in soil and turns it useless in long run

examples of human activities causing this:

• overgrazing

• deforestation

• unsustainable agriculture

overgrazing

too many animals graze in same area

overcropping

depletes soil nutrients, makes soil friable (dry and prone to wind erosion)

examples of unsustainable agricultural techniques

• total removal of crops after harvest (soil open to erosion)

• growing crops in rows with uncovered soil between

• plowing in direction of slope (becomes channels for rainwater)

• excessive use of pesticides (toxification)

• irrigation (salinisation)

• monocultures (same crop year after year; same nutrients depleted)

urbanisation

land in cities paved → increasing run-off to elsewhere → erosion. (urbanisation also commonly covers prime agricultural lands because our cities historically were placed by this)

three major processes of soil erosion

1. sheet wash (landslides when storms)

2. gullying (deepening channels on hillsides when rainfall)

3. wind erosion

soil conserving conservation techniques

1. cover crops (between rows)

2. terracing (reduces steepness of slopes)

3. plowing (breaks soil structure, temporary increased drainage. however; bad for structure and microbial activity)

4. contour farming (plowing parallel to slope; erosion reduced. however; machines tip over)

desertification

when eg. grasslands gradually erodes into desert