Water and Agriculture

Question 1

reasons for increased food demand

Answer 1

• increasing pop
• increasing wealth, thus increased demand for meat/dairy and increased need for grain

Question 2

blue water

Answer 2

GW and surface
- agriculture is the largest demand, also has -ve impact in biodiversity

Question 3

agriculture impacts on blue water

Answer 3

( below
- surface water
- GW )

Cultivation
- sediment transport of nutrients and pesticides
- nutrient release and leaching

Fertilisation
- nutrient runoff leads to neutrification
- nitrate and pathogen contamination

Manure spreading
- spread in frozen ground and rain leads to pathogen, P and N contamination
- nitrate and pathogen contamination

Pesticides
- ecological dysfunction
- decreased water quality from leaching

Housed livestock
- contamination from animal waste containing metals and medicines
- decreased water quality from leaching of nitrates and metals

Manure storage
- spills and overflows releases medicines and pathogens
- releases of medicines and pathogens though leakage and infiltration

Farmyard runoff
- pathogens and medicines
- local leaching of pathogens and medicines

High density of grazing livestock
- reduced infiltration and increased runoff

On farm fuel storage
- local petrocheical contamination from above/below ground storage

Septic tank
- N/A
- local leaching of pathogens, metals and human medicines

Clear cutting
- land erosion leads to increased turbidity
- reduced recharge

Aquaculture
- eutrophication
- N/A

Question 4

seasonal nitrate losses

Answer 4

higher in the winter
- no aerable crops
- mineralization to nitrogen by microbes is low

Question 5

meet growing food demand by …

Answer 5

• increasing rainfed lands
• reducing food waste
• increasing water productivity by improved management of rain water

Question 6

irrigation
- pros
- cons

Answer 6

pros:
- increases crop yield
- protection against climate variability

cons:
- fertilizer/persticide run off (surface)
- saltwater intrusion at the coat (GW)
- increased soil salinity and water log

Question 7

irrigation
- types
- efficiency

Answer 7

types
- flood, 60-90%
- sprinkler, 65-90%
- drip, 75-90%
- raingun = hosepipe <= 90%

Drip
- slowly applied straight to the root zone
- potential to be the most efficient
- compared to flood, increased yield and water productivity with reduced water application

Question 8

best management practices

Answer 8

• to reduce agriculture impacts
• serve to increase efficiency, safety and profitability
• can be voluntary or regulated
• eg. when to apply manure and controlling nitrates, Nitrate Vulnerable Zones also have closed application periods

Question 9

tech to reduce agriculture impacts

Answer 9

• agriculture water treatment
• precision agriculture
• water/snow harvesting
• reduced risk pesticides

Question 10

precision agriculture
- what
- needs
- pros

Answer 10

• reduce agriculture impacts

what
- consider spatial distribution of crop factors
- apply variable rate treatment based on ^

needs
- GPS = global positioning system
- GIS = geographic information system
- field stress
- VRA = variable rate applicators
- real time data and dignostics

pros
- increase profitability
- reduce environmental impacts

Question 11

constructed wet lands
- pros
- characteristics

Answer 11

• agricultural water treatment
• artificial pond with vegetation and biofiltration capabilities
  —- area supporting hydrophytic plant growth
  —- continually wet substrates (soil)
  —– non-soil substrates (rock) that have some water cover

pros
- cheap
- passive
- practical
- remove BOD, DD, N, P, ect.
- habitat creation

characteristics
- 10 o 15h minimum retention time
- hydraulic loading rate of 0.2 to 0.1 m/day

Question 12

permeable reactive barriers

Answer 12

• agricultural water treatment
• reactive porous material that catches pollutants
• materials
  —– water treatment sludge
  —– steel production slag
  —– ochre sludge