Unit 5 Flashcards
Types of Agriculture
- Arable (crops) vs. Pastoral (domesticated animals)
- Nomadic Herding – on the move
- Subsistence Agriculture – targets are small
- Industrialized Agriculture – targets are cash crops
Subsistence Agriculture
- Family Farms
- Slash and Burn/Shifting Cultivation-abandon unfertile soils over time
Industrialized Agriculture
- Human presence has changed land with environmental implications
- No opportunity for the land to ‘rest’
- Intensive harvesting and depleting nutrients and the organic soil matrix
Subsistence
production small with goal to produce for family and local community
- Common in developing nations
- Popularity sporadic in developed nations
Industrialized
production on large, commercial farms to maximize profit
- Yields enhanced through large inputs of capital, energy, and labour
- High level of mechanization
- Chemical pesticides, herbicides, and fertilizers
- Species diversity is not a priority
- North America, China, and Russia
Enhanced Crop Production to Feed Population and Avoid Starvation
- Required the introduction of effective technologies
- Resulted in lower production costs because there was far greater yields/productivity out of the same area of land or resource invested
- Required less land to be cultivated to achieve production but it also led to ability to exploit less productive/marginal lands areas as well
effective technologies
- High yield crops and new crop varieties (wheat, corn and rice)
- Chemical fertilizers (Haber Process for example)
- Synthetic pesticides
- Multiple cropping (more than one crop each year)
Impacts of Intensive Agriculture Problems with the Green Revolution
- Water issues
- Air pollution
- Land degradation
- Loss of biological diversity
Soil Structure
- Attributes that make soils clump and crumble
- Provide sufficient drainage and infiltration of air and nutrients
- Water retention
Soil Fertility
- ability to grow crops and sustain ability to do so over the long term
- Nutrients
- Water
- Air
- Soil organic matter - Soil community contributing to the organic layer (humus) litter and dead organisms at various stages of decay
- Black colour of soils
4 major components found in soils
- organic matter
- minerals
- water
- air
Soils – Features and Formation
- O horizon (organic)
- A horizon (topsoil; light, dark and can erode away; leaching activities move materials deeper)
- B horizon (subsoil; accumulation of materials from A layer)
- C horizon (weathered rocks; groundwater)
- Bedrock - parent material
- Climate affect soils and formation
Soil Texture
Different particle sizes - sand, silt, and clay
-Sand and silt are largely the mineral quartz and cannot hold plant nutrients as these tend to leach easily with rainfall
Aggregate Stability
- We want them to clump but also crumble
- If particles separate there is greater risk of erosional processes but also crusting that limits efficient water percolation into the ground and possibly more runoff to the nearby ditch and ultimately river
- Doesn’t form clumps resistant to crumbling – clods
- Sufficient pore space to permit the movement of gases and water and easier penetration of root complexes
Cation Exchange Capacity (CEC) – Negatively Charged Clay Particles “Hold” Minerals in the Soil
- Decomposing organics a source of positively charged calcium, magnesium, and potassium for plants
- Acidic soils (H+ cations) contribute to accelerated nutrient loss
- Soils low in CEC have more leaching and nutrients may leach to deeper locations in the soil profile
Soil Ecosystem – Soil Organic Matter
- In a hectare of living soil, there can be up to 300 kg earthworms, 600 kg fungi, 375 kg bacteria, 225 kg of insects and algae
- Soil organic matter is VERY IMPORTANT!
Soil Ecosystem provides
- Increasing fertility through the build up of organic matter and symbiotic interactions
- Reduction in soil erosion and huge increase in water holding capacity
- Breakdown of toxins by decomposing community
- Enhanced carbon storage and long term storage (sequestration)
Boreal Forest
-Acidic and significant leaching, nutrients leached to greater depths in soil profile
Temperate Deciduous Forest
-Accumulation of plant litter sustain high organic content in soils and contribute to high productivity
Temperate Grasslands
- High organic matter accumulates in the upper layers and contributes to highly productive soils
- Minimal leaching found and minerals accessible in upper profile
Arid Desert
- Poorly developed soils due to minimal organic matter development
- Minimal clay content
Tropical Rain Forests
- Soils tend to be acidic and susceptible to heavy leaching due to precipitation
- Little organic matter found in soils due to high rates of decomposition
