APES 5.5-5.8

Furrow irrigation

-Trench dug along crops and filled with water

-Easy and cheap; water seeps into soil slowly

-~66% efficient, 33% water lost to run off and evap

Drip irrigation

-Most efficient, but most costly

-Over 95% efficient

-Holes in hose allow water to slowly drip out

-Avoids waterlogging and conserves water

Flood irrigation

-Flood entire field; easier but disruptive to plants

-Waterlogs soil and drowns plants

-80% efficient, 20% runoff/evap

Spray irrigation

-Ground or surface water pumped into spray nozzles

-More efficient than flood & furrow

-More expensive (requires energy for pumps & movement of sprinklers)

Waterlogging

-Overwatering saturates soil, filling pore space with water

-No air in pores, roots can't take in O2 so they are stunted or killed

-Solution: drip irrigation or soil aeration

Soil salinization

-Process of built up salt

-Groundwater for irrigation has small amount of salt

-Water evaps and salt is left behind in soil, it can reach toxic levels and dehydrate plant roots

-Solution: drip irrigation, soil aeration, fresh water

Global water use

-Industrial: power plants, metal/plastic manufacturing

-Municipal: households (toilets, shower, drinking water)

-Agriculture: water for livestock, irrigation for crops

Aquifers and groundwater

-Groundwater: H2O stored in pore space of rock and sediment layers

-Aquifers: useable groundwater deposits for humans that are replenished by groundwater recharge

-Unconfined aquifers recharge quickly, confined don't

Pesticides

-Chemicals that are toxic to pest, ex: rodenticides, fungicides, insecticides, herbicides

-Genetic diversity causes some pests to become resistant because only non-resistant are killed off

GMOs

-Gene for pest resistant added in plants

-Roundup ready crops are GM to be resistant to herbicide

GMOs and Pesticide use

-Roundup Ready crops have increased herbicide (glyphosate) use

-Bt corn has decreased insecticide bc it makes it own

GMOs and genetic diversity

-GM crops are identically the same

CAFOs

-Also called feedlots: densely crowded method where animals are fed grain to raise them as quick as possible

+ Maximizes use/profit, minimizes cost

- Animals given antibiotics and growth hormones

- Large volume of waste which contaminates water

- Produces large amount of CO2, CH4, and N2O

Manure Lagoons

-Large, open pits for animal waste, contains ammonia, hormones, antibiotics, fecal coliform bacteria

-Heavy rain can flood lagoons, contaminates surface/ground water

-Denitrification of ammonia produces N2O

-Can be emptied in landfills/turned into fertilizer pellets

Free Range Grazing

-Animas graze on gross and grow at natural rate

+ no need for antibiotics

+ no grain production

+ naturally dispersed waste creates fertilizer

+ animals can graze on land too dry for crops

- Requires more land, more expensive

Overgrazing

- Too many animals grazing remove all vegetation, leads to erosion

- Animals compact soil

- Denitrification occurs

+ Rational grazing (moving animals periodically) prevents overgrazing

Inefficiency of Meat

-Producing meat for humans less efficient than producing plants in terms of energy, land, and water use

-Energy: all energy needed to plant, grow, harvest plants to feed to animals plus energy needed to bring water/house animals, and to slaughter/package

-Land: all energy needed to grow plants to feed animals, plus room the animals take up

-Water: all water for crops that animals eat plus water for drinking

Fisheries and Fishery Collapse

Fishery collapse: 90% pop decline in a fishery

-Pop may never recover bc decreased biodiversity, inability to find mates, and inbreeding depression

- Decreases genetic/biodiversity

- lost income for fishermen, lost tourism

Economic impact of fishery collapse

-Overfishing in 1975-1985 leads to lose profit right after

-TOC

Bottom trawling

-Harmful method where a net is dragged across ocean floor

- Bycatch: unintended targets caught

- Stirs ocean sediment (turbidity) and destroys coral reefs

- Decreases biodiv

Fishing down the food web and trophic cascade

-As we deplete large, predatory fish, we move down to smaller ones

-Depletion of small fish pop. limits fishery recovery and decreases food supply of mammals