Wednesday, May 30, 2018

It's Water-Wise Wednesdays with Frannie the Fish! {Irrigation: Agricultural Systems}

This is the second part in Frannie's exploration of irrigation. Check out the first part here!

Over 40% of the world's food supply is farmed on irrigated cropland. Crops and livestock are how farmers make their living.  While it's important to produce as much as they can to make money, it also costs a lot of money to keep the plants and animals healthy and farmers are always looking for new ways to reduce operating costs.

Management practices can include reducing their irrigation cycle by starting later or ending sooner that is usual as well as restricting irrigation to the cooler hours of the day, either in the morning or at dusk.  But different types of irrigation systems can also offer many kinds of benefits to the farmers and crops. Let's investigate some of the most common systems.

Surface irrigation
Water is distributed over and across land by gravity. It's one of the oldest and most common types of irrigation, very easy and cheap due to the lack of mechanical pump. However, because water is simply flooding over the surface, a large percentage of the water is wasted through runoff and evaporation.

Drip irrigation
A type of localized irrigation in which drops of water are delivered at or near the root of plants. In this type of irrigation, evaporation and runoff are minimized.  It is more expensive to install than most other types of irrigation, however, and if the water is not kept clean, the tubes themselves may clog and be more difficult fix or replace.

Center pivot irrigation
Water is distributed by a system of sprinklers that move on wheeled towers in a circular pattern. This system is common in flat areas of the United States. Current technology allows farmers to control their pivot's operation with a smartphone, tablet, or computer. Soil moisture sensors, GPS, and GIS can help determine how and when to irrigate efficiently and effectively.

Lateral move irrigation
Water is distributed through a series of pipes, each with a wheel and a set of sprinklers, which are rotated either by hand or with a purpose-built mechanism. The sprinklers move a certain distance across the field and then need to have the water hose reconnected for the next distance. This system tends to be less expensive but requires more labor than others.

Water is distributed across land by raising the water table, through a system of pumping stations, canals, gates, and ditches and excess water may be able to be collected for reuse. This type of irrigation is most effective in areas with high water tables.

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