Lecture 8: Nutrient crisis in agriculture

Question 1

What is soil fertility?

Answer 1

Concentration of nutrients required for successful growth

Question 2

What is the limiting factor of soil fertility?

Answer 2

Plant nutrients need to be in a biologically active form accessible to plants

Question 3

Which nutrient requires mobilisation in soils?

Answer 3

Nitrogen required weathering or recycling via microbes to become active

Question 4

What is farming?

Answer 4

mining the soil of nutrients so we can eat them

Question 5

Which systems benefit nutrient recycling?

Answer 5

Manure
Compost
Crop residues
Intercropping
Rotation
Weathering (slash and burn)

Question 6

What is weathering (slash and burn)?

Answer 6

burn landscape to introduce phosphorous into soils through biologically-active forms in ash

Question 7

What is the connection between traditional farming systems?

Answer 7

Connection between farming and society as need nutrient return

Question 8

Issues with traditional connected agriculture

Answer 8

prone to famine and over use
at threat if localised
climatic/social events cause food insecurity

Question 9

What happened in the 1800s?

Answer 9

global shipping networks of guarno reserves led to wars over resource allocation

Question 10

What happened in the 1900s?

Answer 10

discovered Haber-Bosch process to convert innaccessible nitrogen gas to ammonia

Question 11

What happened in 1940s?

Answer 11

Uptick in mining rock phosphate

Question 12

What happened in 1960s?

Answer 12

Green revolution

Question 13

What is green revolution?

Answer 13

Plant breeding programmes for productivity and higher nutrient inputs

Question 14

Issues with industrial nutrient cycling

Answer 14

Leaky system
Runoff
GHG emissions
Delocalised nutrient flows restructure society

Question 15

How is industrial nutrient cycling extractive?

Answer 15

Only a few countries produce finite resources
Extraction is occurring at millions of years rate not in line with seasonal use before

Question 16

Positive impacts of industrial farming

Answer 16

Freely expand populations as less famine
Reduced hunger, increased population, maintain land use
Increased productivity

Question 17

Costs of industrial farming

Answer 17

Limited supplies of nutrients
Over application issues
Crop breeding reduced reliance on microbes
Crop breeding has reduced microbe ability to form beneficial symbioses

Question 18

How can we tackle the nutrient crisis?

Answer 18

Tailor solutions to local environments
Prioritise soil health
More diverse, nutrient enhancing crops
Use microbial tools