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ERS 270 > Midterm 1 > Flashcards

Midterm 1 Flashcards

1
Q

Convective

A
  • Hot temperatures make air rise, meets with cool atmosphere and moisture condenses, accumulates in clouds
  • Can cause high winds (tornadoes)
  • Similar to rainfall in the area
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2
Q

Orographic

A
  • Moisture laden air mass meets mountain range & unloads water
  • Replenishes surface water
  • Found in areas like Vancouver BC
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3
Q

Cyclonic

A
  • Changes in atmospheric pressure over the ocean
  • Warm ocean temperatures
  • Strong storms eg. hurricanes (in sub- and tropical environments, but temperate regions receive hurricane fallout)
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4
Q

RAINFALL PATTERNS

A
  • Average total annual rainfall
  • Distribution & periodicity
  • Intensity & duration
  • Availability
  • Predictability
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5
Q

RAINFED AGROECOSYSTEMS

A

rainfall system that only need natural rain fall for their access to water

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6
Q

Long Wet Season

A
  • Humid regions with extended rainfall
  • Problem: excess water
  • Problems with waterlogging
  • Habitat modification to remove water for crop growing
  • Solutions: Chinampa
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7
Q

Wet-Dry Season

A
  • Typical in tropical regions
  • Production of crops during wet & dry season
  • Rain falls have: Specific period large quantity of rain and minimal rain during dry season
  • Wet season: Varies in length & intensity and Crops that need water or tolerate high quantity of water are grown here
  • Dry season: Varies in length & intensity, Crops that tolerate little water, Use of organic mulch, Fallow (during very dry season)
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8
Q

Seasonal Rainfall

A
  • Temperate (like here) & tropical zones
  • Highly variable depending on global location
  • Variably adapted crops work well
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9
Q

DRYLAND FARMING

A
  • Rainfall during crop season insufficient
  • You could just irrigate but some places do not have the money
  • Requirement of crops suited to be productive under less rainfall: No irrigation is used
  • Dryland agriculture = pastoral systems
  • Dryland farming requires: Cultivation system that promotes rainwater penetration & storage in soil and Frequent use of summer fallow
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10
Q

ATMOSPHERIC MOVEMENT

A
  • Movement of disease & pests by wind
  • Movement of salt near ocean
  • Wind can have significant impact on agroecosystems
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11
Q

Desiccation from Wind

A
  • No boundary layer between air and leaf surface
  • Increases transpiration & overall water loss from crop
  • Rate of desiccation exceeds water replacement: Impedes photosynthesis, Impedes crop productivity, and Produces low grain yield
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12
Q

Dwarfing from Wind

A

Direct correlation between wind and crop height

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13
Q

Deformation from Wind

A
  • The side of the plant that the wind hits has less leaves and grows in the direction of the wind
  • Constant wind from prevailing direction alter plant growth form
  • Windbreaks are good indicators of direction of prevailing wind
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14
Q

Plant Damage & Uprooting from Wind

A
  • Excessive winds not usual but can cause severe damage

- Crops experience wind damage when they are nearing maturity and heavy with grain/fruits

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15
Q

WIND EROSION

A
  • Regions with low rainfall = prone to wind erosion

- Wind detaches & transports soil particles

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16
Q

BENEFICIAL EFFECTS OF WIND

A
  • Good air circulation: maintains optimal gaseous exchange between atmosphere & crops, Disperses excess humidity (limits diseases), Cools plants (hot & humid climates), and Essential for crops relying on wind pollination
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17
Q

Wind Breaks

A
  • Also called shelterbelts or hedgerows
  • Composed of trees
  • Reduce Erosion by wind, Protection of homesteads, Improve crop yield
  • Windbreaks Reduce wind velocity by 80%
  • Located perpendicular to prevailing wind
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18
Q

Planting Techniques and wind

A
  • Planting of annuals that protect the main crop from wind
  • Easy & fast to establish compared to windbreaks
  • Provide more flexibility in day to day farming operation
  • Reduce wind velocity
    which improves moisture & temperature for the crop to be harvested and improves crop yield
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19
Q

FIRE IN NATURAL ECOSYSTEMS

A
  • Major form of disturbance/environmental change
  • Some natural ecosystems: dependent on regular fire cycle (eg. boreal forest & jack pine)
  • Accumulation of sufficient fuel, dry conditions and source of ignition = cause of fire
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20
Q

Surface Fire

A
  • Most common fire type
  • Used to control or promote growth of weedy or invasive vegetation
  • These are the ones that re produced by man to increase plant productivity
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21
Q

Crown fire

A
  • Canopy of vegetation is consumed

- Mature plant species are killed

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22
Q

Ground/subsoil fire

A
  • Peat or muck soil fires
  • Occur under ground and smoulder for months
  • Can be caused by coal
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23
Q

Fire Resistance

A
  • Plants are not burned by fire

- Plants with thick bark, fire-resistant foliage, thick litter on soil that withstands frequent fire

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24
Q

Fire Tolerance

A

Re-sprout from the crown after fire

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25
Q

Fire Dependence

A
  • Require fire for reproduction or long-term survival
  • Seeds require fire in order to germinate and sprout
  • Some plants have flowers that will not emerge until after a fire
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26
Q

Fire in Agroecosystems -Shifting Cultivation

A
  • Ancient technique of agriculture
  • Regular use of fire in shifting cultivation to clear vegetation that has been cut down
  • Burned vegetation increases soil pH & increases nutrient mobility for growing crops
  • Shifting cultivation: sustainable if populations are low
  • Modern problem: population numbers increase, fallow phase decreases, agriculture becomes settled, soil becomes degraded
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27
Q

Fire in Agroecosystems -Land Clearing

A
  • Easily accessible tool to clear land (forest) for agricultural conversion
  • Often done unsustainably
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28
Q

Fire in Agroecosystems -

Nutrient Additions to Soil

A
  • Left over products after burning add nutrients to the soil

- Ash, charcoal

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29
Q

Fire in Agroecosystems -Crop Residue Management

A

Fire used to manage crop residues

  • Fire releases N from burning crop reesidues for next crop cycle
  • Burning crop residues decreases requirement for tillage
  • Sustainability: Is the burning of crop residues a good thing? See slide 24 on advantages/disadvantages
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30
Q

Fire in Agroecosystems - Weed Management

A
  • Fire can reduce weeds in the litter or seeds in the soil
  • Fire can reduce weeds shortly after they germinated
  • Some weeds are perennial or fire resistant: burning may actually stimulate weed growth
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31
Q

Fire in Agroecosystems - Pest & Disease Management

A
  • Fire can control arthropods (insects, mites)

- Higher temperatures created by fire control pathogens such as fungi, nematodes, bacteria

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32
Q

Fire in Agroecosystems - Facilitation of Crop Harvest

A
  • Fire can help prepare crops for harvest
  • Environmental consequences of burning: Particulates in air, CO2 emissions, other issues with effect of fire on soil as discussed earlier
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33
Q

Agroecology - Brief History

A
  • Early concepts date back to early 20th century
  • Did not achieve recognition as a field of study till 1990
  • Became recognized in 1980s in tropical agriculture as a result of community based development
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34
Q

Agroecosystems ≠ natural ecosystems

A
  • Human manipulation makes agroecosystems different
  • Processes are the same
  • Structure and function different
  • Energy flow in agroecosystem: Open system with High input and high output
  • Nutrient Cycling in Agroecosystem: Minimal recycling with High input and high losses
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35
Q

Negative Effects of Modern Farming

A
  • Fossil fuel consumption
  • GMO: does it affect human health?
  • Contributed to environmental pollution
  • decreased crop diversity
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36
Q

Fertilizer to environmental pollution

A
  • 50% of N fertilizer applied taken up by crops

- 30% of p fertilizer applies taken up by crops

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37
Q

decreased crop diversity

A

98% of global population relies on only 50 different types of crops

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38
Q

Intensive Tillage

A
  • Complete, deep, and regular manipulation of soil

- Loosens soil: better drainage, aeration, fasten root growth, increased soil temperature

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39
Q

Mono-culture

A
  • Mono-culture = simple agroecosystems
  • Forms moved from producing a high diversity of crops to growing only a few crops
  • Simple agroecosystems: Efficient use of form machinery, Minimal labour costs, Maximal technology inputs, and Intensive agriculture practices
  • Monoculture vs sole crops
40
Q

Macronutrients Access

A
  • Oldways: animal and human manure

- Today: increased demand for cheap food: created by the Development of fertilizer industry

41
Q

Nitrogen

A
  • Legumes: convert N2 to plant available N: Insufficient in N for industrial agriculture
42
Q

Phosphorous

A

Come from Natural rock deposits

43
Q

Potassium

A

Come from potassium desposits

44
Q

Agrochemicals

A
  • Insecticides, pesticides, herbicides, fungicides
  • Removes organisms that threaten crop productivity
  • Agrochemicals treadmill: Once you got on it you cannot get off it
  • Agrochemicals are like steroids
  • Chemicals remove beneficial and unbeneficial consequences
45
Q

Why is industrial Agriculture not sustainable?

A
  • Soil degradation
  • Overuse of water
  • Pollution
  • Destruction of natural habitat
  • Dependence on external inputs
  • Production of GHG
  • Loss of genetic diversity
46
Q

No Control in Industrial Agriculture

A
  • Few farms controlled by large corporations
  • Is modern crop and food production healthy: Global obesity issues
  • Food waste issues
  • Unequal food distribution
47
Q

Soil

A
  • Soil is not dirt

- The interface between living (biotic) and non-living (abiotic)

48
Q

Pedosphere

A
  • The interface between living (biotic) and non-living (abiotic)
49
Q

5 main factors contributing to Soil Formation

A
  • Climate: Temperature and precipitation influences weathering rates
  • Topography: Slope steepness
  • Biology: Plants and animals that contribute and decompose organic matter, addition of nutrients
  • Geology: Type of rocks broken down
  • Time: Takes a while to form soil
50
Q

Takes a while to form soil

A

1cm soil/ 178 years

51
Q

Elluviated and Illuviated

A

Elluviated : leached soil horizon

Illuviated: receives leached materials

52
Q

Soil Texture

A
  • Also referred to as soil separates
    o Sand = 2 to 0.05mm
    o Silt = 0.05 to 0.002
    o Clay = smaller than 0.002
53
Q

Soil Structure

A
  • The arrangement of soil particles based on Particle size, Shape, and Soil texture also influences structure
54
Q

What contributes to different soil structure?

A
  • Organic matter content and presence of microorganisms
  • Chemical reactions
  • Wetting and drying
55
Q

Soil Colour

A
  • Different soil colours occur:
    ~ Mineral composition (Iron = red colour)
    ~ Organic matter content (Black or dark brown)
    ~ Drainage (Green or blue = poor aeration)
  • Munsell Soil Color Chart
    ~ Determines soil colour
56
Q

Cation Exchange Capacity in Soil

A
  • Complex chemical reaction between soil particle and plant roots and nutrient in soil solution/water
  • Caution exchange (northern atmosphere): Occurs when soil pH is greater that 5.2
  • Anion Exchange (tropical soil): Occurs when pH is lower than 5.2
57
Q

Acidity and pH

A
  • Occurs in soils with more than 500mm rainfall/year

- Low pH causes decrease in crop yield

58
Q

Low PH can be amended by adding…

A

Lime, Biochar, ash

59
Q

Saline Soil

A
  • Common in soils of arid and semi-arid regions
  • Excessive irrigation: salt (Na, Cl) build-up in soil
  • Excessive use of salt-based fertilizers
  • Problem with the soil solution
60
Q

Sodic (Alkaline) Soil

A
  • pH of 8.5 or higher
  • contain neutral salts
  • caused by SOM dispersion and Difficult water infiltration
  • Problem with the soil of itself
61
Q

Soil Organic Matter to Soil Organic Carbon

A
  • SOM -> SOC (divide by 1.724)

- SOC -> SOM (Multiple by 1.724)

62
Q

Crop Residues

A
  • Industrial agriculture: lower residue input than natural ecosystems
  • Therefore Important source of OM for Soil and should not be removed
63
Q

Cover Crops

A
  • Plant cover specifically grown to produce plant matter for incorporated into soil or left on surface
  • Usually grown in rotation
64
Q

Manure

A
  • Adds Organic matter and nutrients
  • Addition of fresh manure requires compositing and stabilization time in field
    and Takes time until nutrients become available
65
Q

Compost

A
  • Optimal Carbon/Nitrogen ratio
  • Optimal particle size
  • Generally free of weed seeds (which is good)
  • Soil diseases oppressed by compost application
  • Issues: Inconsistent product and May contain contaminants
66
Q

Biosolids

A
  • Solid material removed from wastewater

- Can be applied only every 5 years Because it can contains heavy metals

67
Q

Conventional Tillage

A
  • Controls weeds, pests, prepares seed bed

- Decreases soil structure, and a lot of other bad stuff

68
Q

Crop System Complexity

A

Diversifying our crops

69
Q

Movement of water in Soil

A
  • Infiltration
  • Percolation
  • Evaporation
70
Q

Annual Crop Roots have…

A

Majority of roots in the top 30cm of soil

71
Q

Perennial Crop Roots have…

A

Deep rooted systems

72
Q

Wet Spring vs Dry Summer (not good)

A
  • Shallow root system

- Water efficiency issues in summer

73
Q

Dry spring vs wet Summer (kinda good)

A
  • Deep root system

- No water deficiency issues (even if summer is dry

74
Q

Excess Water in the Soil

A
  • Causes water logging: Poor drainage

- Waterlogged soil found globally

75
Q

Negative Effects of Too Much Water

A
  • Anaerobic environment (without oxygen)
    o Different microbes
    o Limit plant production
76
Q

Seasonal drought

A
  • Reduces build-up of diseases and pests
  • Acts as frost in northern climates
  • acts as flooding in wet/tropical areas
77
Q

Evapotranspiration

A

the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces and by transpiration from plants

78
Q

Reducing Evapotranspiration

A
  • Crop Choice and Agroecosystem Design (Using crops with low water needs, Increasing vegetative cover, Using fallow periods, Increasing crop diversity)
  • Organic Mulch
  • Inorganic Mulch
79
Q

Photosynthesis

A

plants capture CO2 from atmosphere and convert it into energy (C fixation)

80
Q

C3 Photosynthesis

A
  • Use the Calvin cycle to fix C
  • Most widespread form of C fixation
  • Plants thrive in cool conditions
  • Examples: wheat, oats, beans, tomatoes, woody plants (trees, shrubs)
81
Q

C4 Photosynthesis

A
  • Use a hatch-slack pathway to fix C
  • C fixation occurs at a lower concentration of CO2
  • C4 plants use less moisture under warm and dry conditions: Common in tropical areas and Higher biomass accumulation in tropical areas
  • Examples: Sorghum, Sugarcane
82
Q

CAM Photosynthesis

A
  • Crassulacean Acid Metabolism
  • Similar to C4 Pathway
  • CAM plants common in hot and dry environmental
  • Plants minimize photorespiration and save water by separating these steps in time, between night and day
  • Example: cacti, pineapple, succulents, other bromelaids
83
Q

Sink

A

Harvestable product

84
Q

Nitrogen

A
  • Most limiting nutrient in temperate agriculture
  • Added in large quantities
  • Uptake from soil by roots as NO3 and NH4
85
Q

Phosphorus

A
  • Most limiting nutrient in tropical agriculture on acidic soil
  • Plant available P low
  • Plant acquisition via uptake from soil by roots
86
Q

Potassium

A
  • Important in metabolic processes
  • K deficiency creates a uneven plant water balance
  • K abundant in soil
  • Excessive removal via harvest
  • K leaches easily from soil
  • Plants get it through their roots
87
Q

Light Variation in the environment influenced by…

A
  • Seasons – the time
  • Latitude –closer to the equator the more even the day light period is
  • Shade (canopy structure)
  • Topography
  • Air quality
88
Q

Light Variation - Seasonality and Latitude

A
  • Angle of sun controls daylight hours and intensity

- Equator vs the poles

89
Q

Light Variation - Altitude

A
  • Increase in light intensity with increasing height

- Plants have adapted to control the amount of light reaching leaves

90
Q

Light Variation - Topography and Air Quality

A
  • Topography
    ~ Slope and direction of soil surface
    ~ Slope orientation (north vs south facing)
  • Air Quality
    ~ Suspended particles decrease amount of light reaching plants
    ~ Limits plant growth and productivity
91
Q

Light Variation - Canopy Structure

A
  • Simple vs complex agroecosystems (has more vertical complexity)
92
Q

Temperature Influenced by

A
  • Latitude (angle of sun)
  • Altitude
  • Seasonal variation (northern hemisphere)
  • Topography (slope orientation)
  • Water bodies (maritime): Large bodies of water moderate temperature fluctuations therefore Warmer winter, cooler summers
93
Q

Response of Plants to Temperature (what plants need to adapt to)

A
  • Higher temperature causes greater evaporation
  • Diurnal temperature variation extremes
  • Vernalization: Some Plants require period of cold (Herbaceous species need cold spells)
94
Q

Canopy Vegetation

A

Trees and tall plants

  • Provide shade and change temperature
  • Agroforestry practices
95
Q

Non-Living Canopies

A

Crops not grown under agroforestry practices

  • Use of nonliving canopy
  • Strawberry production in California
  • Soil surface cover
  • Increases soil temperature and microclimate
  • Greenhouses, hoop houses

ERS 270 (1 decks)

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