Amanda has taught high school science for over 10 years. They have a Master's Degree in Cellular and Molecular Physiology from Tufts Medical School and a Master's of Teaching from Simmons College. They also are certified in secondary special education, biology, and physics in Massachusetts.
What is Irrigation?
Picture a hot day, you're sweating, and the sun is beating down on you. Wouldn't a nice, cool glass of water be refreshing? Of course! Now, picture how your plants look on such a hot day. They probably look wilted and not so great. What do the plants need?
The answer is water, just like you!
All plants need water to go through a process called, photosynthesis, through which they make their own food to grow, develop, and ultimately produce the fruits and vegetables that we eat. When plants don't have water, they cannot perform this process, and they die.
What would happen if all the plants died? Well, we would die, too! We would have no more food, the animals we eat wouldn't have food, and our whole ecosystem would collapse. This is why farmers, from the beginning of time, have used a technique called irrigation. Irrigation is the process of artificially supplying crops with water. This technique is especially important in areas that receive little rain or irregular rainfall.
Types of Irrigation
There are many types of irrigation, and farmers choose which one to use based on the environment they are farming in. Let's go over the most common methods.
The first type is surface irrigation, which uses gravity to distribute water over the field. Water flows from an area of higher elevation downhill to reach all the crops. Unless the land is naturally sloped, this form can be very labor intensive. A classic example of surface irrigation can be found in the rice paddies in East Asia, where land is dug into terraces and water flows from the top to the bottom, watering each plot of land.
Localized irrigation uses a system of tubes to pump water throughout the field. This form includes drip irrigation, which delivers water droplets directly to the roots of plants.
You probably are familiar with sprinklers, either from running through them as a child or using them to water a lawn. Sprinkler irrigation involves a system of pressurized tubes that expel water onto crops. Variations include rotary irrigation in which the sprinkler system whirls around, applying the water in a circular motion.
The central pivot is another type of irrigation that uses sprinklers. Just like when you pivot a car, or turn while on foot, these sprinklers change directions to water the entire field. The sprinklers are mounted on mechanical tracks that move them in a circular motion as they spray water on the crops.
Sprinkler systems also include lateral move irrigation. This type of irrigation also uses sprinklers, which move manually or mechanically across the field and then reconnect to a hose. While lateral move irrigation requires more effort, farmers may find it more economical.
Sub-irrigation can be used if the water level, or water table, in an area is close to the surface, which we call a high water table. Irrigation through pumps raise the water table, causing more water to be accessible to the roots of plants. Similarly, flood irrigation can be used to saturate the entire field, giving crops plentiful water.
The most labor intensive but cheapest way of irrigation involves carrying buckets of water by hand to crops.
Problems with Irrigation
Although irrigation has allowed us to create a massive global food supply, it is not without problems. The main issue with irrigation is contamination of crops. If bacteria or chemicals are present in a water supply, the entire field can be compromised. Irrigation systems are like personal budgets; it's important to not spend more than you make. This means not using water faster than it is being replenished at the source. If this happens, the water supply can run dry—not only for the farm but for the surrounding community.
In summary, irrigation is the process of using artificial methods to provide water to crops. Surface irrigation involves the use of gravity to spread water on crops, while localized irrigation utilizes a system of tubes and pumps to deliver water to plant roots.
A wide variety of irrigation techniques that use sprinklers to spray water over crops are also available, such as rotary irrigation, which sprays water in a circle. Central pivots rely on the rotary method, but here, the sprinklers also move in a circle, covering more ground with water. Lateral move irrigation involves manually moving the sprinklers around the field and reconnecting the hose.
Sub-irrigation raises the water table to make water more accessible to plants, while flood irrigation fills the whole field with water. Problems with irrigation include potential contamination of crops and depletion of the water source.
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