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Feeding 9 Billion > Midterm 1 > Flashcards

Midterm 1 Flashcards

0
Q

What are grains forages and fiber crops

A

Greens or anything that produce small hard seeds, like cereals and pulses. Forages are any crops who’s vegetative part is he is for animal feed. Fiber crops or anything that are used for nonfood uses like clothes.

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1
Q

When did agriculture start

A

Roughly 10,000 years ago at the end of the last Ice Age

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2
Q

What are nightshades

A

Tomatoes potatoes and peppers

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3
Q

Agriculture land area and percent

A

Ag area. 5 bill. 38%
Crops. 1.5. 12
Pasture. 3.5. 26

Wheat. 220 mill. 15%
Maize. 170 mill. 11
Rice. 165 mill. 11

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4
Q

How much of total calorie consumption is cereal? Proteins? Percent of total crop area?

A

46% of calories in the global diet. 40% of protein in the diet. One third of total crop area.

Hi energy density and proteins. Taste. Store well. Easy to prepare. Breadmaking.

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5
Q

Two ways to increase crop production?

A

YIELDS:
LAND AREA:
Recent contractions and some Cereals. Recent expansion and oil props. Expansion largely concentrated in Latin America.

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6
Q

Why are corn and soybean increasing?

A

Ethanol

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7
Q

Water limited yield

A

Maximum possible yield given available water, rainfall

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8
Q

Yield potential

A

Maximum possible yield given solar radiation, CO2, Crop Genetics, and temperature

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10
Q

Nutrient limited yield

A

Maximum possible you’ve given available nutrients, N,P,K etc.

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10
Q

Yield

A

Mass of harvested product per hectare per season

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11
Q

Actual yield

A

What farmers achieve

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12
Q

Defining factors, Yp

A

Carbon dioxide, radiation, temperature, Crop Genetics

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13
Q

Reducing factors, Ya

A

Weeds, tests, diseases, pollutants

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14
Q

Limiting factors, Yw/Yn

A

Water, nutrients

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15
Q

C4 versus C3

A

C4 performs more efficient photosynthesis, corn is an important C4 from

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16
Q

Water function and percent

A

Water content is 70 to 90% of fresh wait. Important functions:transpiration for cooling in the train transport, medium for biochemical processes, solvent for nutrients, turgor plant rigidity. It is the number one constraint and most systems

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17
Q

What is the difference between T and ET?

A

T is the total crop transportation, the total amount of water leaving the store mates. TE is the transpiration efficiency of a plant.

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18
Q

When considering plant growth do you want ET to be larger than T?

A

Not by much, we don’t want water to be evaporating the of the soil. Big T means more biomass so we don’t want that to be large.

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19
Q

Why are values higher at low yields?

A

?

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20
Q

Liebig’s “law” of the minimum

A

the most limiting nutrient at a given site matters most

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21
Q

Nutrient Gains

A
  1. Fertilization (largest gain)
  2. Mineralization (unavailable -> available)
  3. Fixation (for N, legumes)
  4. Deposition (for N)

• N fixation can be plant-associated (legumes) or free-living
• Mineralization and Immobilization depend on soil acidity
(P deficient in acidic soils, Zn deficient in basic soils)

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22
Q

Nutrient Losses

A
  1. Leaching, Erosion
  2. Immobilization (available -> unavailable)
  3. Harvest
  4. Gaseous losses (for N)
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23
Q

Why are nutrient balances negaSve in Africa?

A

• Negative in most African countries: § Little fertilizer application

§ Losses due to harvest and erosion § Results in low yields
• Positive in China and other emerging economies: § Excessive fertilizer application
§ Results in soil acidification and eutrophication

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24
Q

What happens to fertilizer use efficiency over time?

A

Negative nutrient budgets [declines]- > positive nutrient budgets [overshoots] -> well balanced

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25
Q

protein percentages and nitrogen relation

A

• Typical grain protein contents:
wheat 13%, rice 7%, maize 9%, soy 40%
• NITROGEN x 6.25 %= PROTEIN

26
Q

Nitrogen Use Efficiency

NUE 
NUEf
NUpE
NUtE
NUEa
A

• NUE = yield/all nutrient inputs

• NUEf= yield/total fertilizer application
• NUEf can be decomposed into:
§ Uptake efficiency (NUpE) = plant uptake/total application § Utilization efficiency (NUtE) =yield/uptake
§ NUEf = NUpE x NUtE
• NUEf chances over time: generally declines and then improves as systems mature

• NUEa = yield increase*/ total fertilizer applicaSon
* Compared to yields without any fertilizer inputs

27
Q

How much production is lost to biotic stresses?

A

• 30% of potential production is lost to biotic stresses

• Types of constraints – Diseases
– Animal Pests (insects, nematodes, rats, birds) – Weeds

28
Q

What is TFP?
Productivity?
PFP ?

A 
•  Total Factor Productivity = total value of all outputs / total value of all inputs (Food Prices)
•  Productivity = outputs / inputs
•  Partial Factor Productivity = single output /
single input (Scarce resources)
– Yield, Land, Labor
29
Q

Tillage

A
  • Reasons to do it—breaks up soil, kills weeds, helps decompose residue, controls diseases and pests, incorporates manure
  • Reasons to not do it—increases erosion, speeds up loss of soil organic maker, increases soil compaction, requires labor and fuel and time, increases evaporation
30
Q

Crop Rotation

A
  • Fallow season for water scarce regions
  • Cover crops for nutrient scarce regions
  • Asia: rice / wheat or USA: corn / soy
  • Reasons for doing it—reduces pest and weeds, improves nutrient supply, improves soil structure
  • Reasons for not doing it—lack of experSse or equipment, lower profitability
31
Q

What are the 3 parts of conservation agriculture?

A

residue retention, reduced or no till, crop rotations

  • Reasons for doing it—reduces erosion, increases organic matter, conserves soil moisture, lowers fuel and labor costs, faster turnaround for next crop
  • Reasons for not doing it—need new equipment, higher weed pressures and herbicide dependence, hard to add manure
  • USA, Brazil and Argentina have the most area under no tillage
32
Q

5 Methods of Integrated Pest Management

A

– Cultural: rotations, maintain good crop nutrient and water levels
– Biological: beneficial insects like parasiSc wasps, bacteria, push-pull management
– Mechanical: traps, handpicking, Sllage
– Chemical: pesScides, fungicides, herbicides,
nemaScides—trends in use?
– Genetic: develop plants with resistance but its the red queen metaphor, is a conSnual race against the geneSc evoluSon of pests—to slow the race farmers plant refuges

33
Q

Energy Productivity

How much energy Ag uses

A

– Consumes about 10EJ—60% indirect and 40% direct
– 2% of global energy use, which is 530EJ
- declines after initial big energy input over time

34
Q

wheat rice and corn consumption per year

A

We consume about 700 mil tons of wheat, 500 mil tons of rice and 900 mil tons of corn per year

35
Q

calories consumed in last 2000 years

A

Consumed 1x10^18 calories in the past 2000 years

– We will consume a third of that over the next 50 years

36
Q

Synthetic N used per year

A

• Globally, 119 mil tons of synthetic N fertilizer is used per year

37
Q

if we used available manure for N instead?

A

only about 10% of synthetic fertilizers could be displaced by manure
– Better to focus on improving efficiency of fertilizers than using more manure

38
Q

Deadly Striga

A

• Striga is a parasitic weed spreading across Africa
• Its spread is driven by rising soil temperatures
and low soil fertility
• The weed reduces maize yields in SSA by up to 80%, threatening the livelihoods of 100 million farmers
• Intercropping and the use of chemical treatments are the most common strategies employed to combat the spread of Striga

39
Q

Takeaways from Readings: When Weed Killers Stop Killing

A
  • Glyphosate (Roundup) is a herbicide that disrupts plants ability to grow by interfering with their ability to construct new proteins
  • Although Roundup has gained massive popularity in agriculture because it’s easy to apply and has been extremely effective in the past, weeds are becoming resistant (ex: waterhemp)
  • In response, US farmers are increasing the use of secondary herbicides, known as residuals
40
Q

Australia

Reliance on chemical control

A
  • Never put all your eggs in one basket
  • Relying on only herbicides resulted in very resistant ryegrass
  • Key was turning to non-chemical approaches like destroying weed seeds using chaff carts
41
Q

India

Time, money, and resource constraints

A

• Burn the rice fields to make way for wheat— releases 12 megatons of carbon dioxide
– Horrible for the soil, biodiversity, climate
• New equipment is too expensive or there’s not enough info about it

42
Q

Vietnam

Overuse of Pesticides

A
  • Misunderstandings lead to overuse of pesScides
  • Killed off natural pest predators so the planthoppers were free to roam
  • Planthoppers also developed resistance—needed 500 Smes more pesScide than before to kill them
  • Farmers finally changed after doing a comparison between the recommended amount and the normal amount they were using—the former had equivalent or higher yields
43
Q

Current growth in wheat, rice and soy yields per year

A

1%

44
Q

Two ways to get lots of biomass

A
  1. Grow fast
    Growth= photosynthesis – respiraSon
  2. Grow for a longer season
45
Q

When a seed grows into a full crop, where does most of the added crop mass come from?

A

Gasses in the air (particularly CO2)

46
Q 
Why do the following factors matter for yield potential?
•  Radiation
•  CO2
•  Genetics
•  Temperature
A
  • Radiation - photosynthesis
  • CO2 - photosynthesis
  • Genetics – growth rates
  • Temperature – growth rates
47
Q

How big is one hectare?

A

2.47 acres
100m x 100m
Roughly 2 football fields

48
Q

How much of total land area is arable?

A

11%

12% = arable land + permanent crops like trees

49
Q

What does yield potential mean?

A

Maximum possible yield, given

  • -solar radiation
  • -CO2
  • -temperature
  • -crop genetics
50
Q

Between actual yield, water-limited yield and potential yield, which tends to be the highest?

A

Potential yield

51
Q

Equations

A
  • Yield = Biomass x Harvest Index
    • Biomass = Growth Rate x Growth Duration
    • Biomass = T x TE
    • TE = Kc/VPD
    • T = ET x (T/ET) what you care about is the fraction of
      evapotranspiration that is transpiration
    • Yield = Total Fertilizer x NUEf
52
Q

T

A

T= total transpiration = Biomass / TE (Trans Efficiency)

53
Q

TE

A

TE = transpiration efficiency = Biomass / T (total trans)

54
Q

Kc

A

Kc = crop specific constant

55
Q

VPD

A

VPD = vapor pressure deficit (in units of Pa)

56
Q

ET

A 
ET = total evapotranspiration
T/ET = fraction of ET that is from T
57
Q

Kc Values

A

wheat 6
Corn 9
Soy 5

58
Q

global synthetic fertilizer use

A

200 million tonnes per year
119 millt­ Nitrogen,
28 millt ­Potash,
46 millt­ Phosphate

59
Q

Increase T

A

One way to increase T/ET is to reduce E by planting a quick­growing cover crop that will keep the water from evaporating out of the soil. Also, you can increase the T from the main crop by getting rid of weeds in the field that are transpiring water that could be used for the crops.

60
Q

Increase ET

A

Having longer and faster growing root systems can increase the plants’ access to water in the soil and in turn, increase ET.

61
Q

Increase TE

A

this can be changed only by growing a different crop variety with higher transpiration efficiency or by growing the crop in a climate with a lower vapor pressure deficit.

62
Q

Increase HI

A

This can be changed by breeding new varieties that invest in making grain even during bad climate­related episodes like drought.

Feeding 9 Billion (2 decks)

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