Irrigation Methods (APES 5.5)

Spray cons

-Larger up-front cost than flood/furrow irrigation -Can include machinery run with electricity/fossil fuel use -Nozzles can clog -Pivot systems can wear ruts in soil

Flood cons

-requires water nearby -not for all plant types -land must be graded -levees needed -waterlogging/salinization

Ogallala aquifer

World's largest aquifer; under parts of Wyoming, South Dakota, Nebraska, Kansas, Colorado, Oklahoma, New Mexico, and Texas (the Midwest). Holds enough water to cover the U.S. with 1.5 feet of water. Being depleted for agricultural and urban use. *Tragedy of the commons (being used faster then it can replenish itself) recall video*

Furrow irrigation

involves digging trenches and filling them with water

Furrow pros

-Low investment -High-sediment water can be used -Allows for some precision of application

Furrow cons

-Not efficient on sandy soil -Difficult to apply small amounts -33% of water lost to evaporation -Soil erosion

Spray pros

-Precision application -Supplements can be introduced into the water -Efficient: 25% or less lost to evaporation -Can be programmed to run at certain times of day

Salinization fixes

-Spend lots of money to flush field with fresh water until all salt water is flushed out -Grow plants that are salt-tolerant

Drip cons

-Very expensive, clogs easily -Requires mechanization -Placement makes any other processes difficult

Drip pros

-Very low evaporation rates (5%) -Reduced nutrient leaching -No land grading needed

Flood pros

-easy -inexpensive -mechanization not required

Waterlogging fixes

-select crops adjusted to this habitat -Let it dry out -Drain it

Aquifer

A body of rock or sediment that stores groundwater and allows the flow of groundwater.

Salinization

Accumulation of salts in soil that can eventually make the soil unable to support plant growth.

70%

How much agricultural water is used for irrigation

Drip irrigation

a process by which pipes placed near plant roots drip only as much water as the plants need; Most efficient irrigation method *Developed countries

saltwater intrusion

an infiltration of salt water in an area where groundwater pressure has been reduced from extensive drilling of wells

Waterlogging

saturation of soil with irrigation water or excessive precipitation so that the water table rises close to the surface

Flood irrigation

water is distributed over the soil surface by gravity; the most common form of irrigation and most inefficient; loses 40% of water *used in developing countries

Spray irrigation

water is pumped from a well into an apparatus that contains a series of spray nozzles that spray water across the field *Developed countries