In Question 6, you will be asked to listen to part of an academic lecture and to

Two types of irrigation methods that are used worldwide are mentioned in your textbook. Flood irrigation—that’s been a method in use since ancient times—and we still use it today where water’s cheap. Basically, canals connect a water supply like a river or a reservoir to the fields where ditches are constructed with valves, uh, valves that allow farmers to siphon water from the canal, sending it down through the ditches. So that way the field can be totally flooded, or smaller, narrow ditches along the rows can be filled with water to irrigate the crop. But, this method does have quite a few disadvantages. Like I said, it’s contingent upon cheap water because it isn’t very efficient and the flooding isn’t easy to control, I mean, the rows closer to the canal usually receive much more water, and of course, if the field isn’t flat, then the water won’t be evenly distributed. Not to mention the cost of building canals and ditches and maintaining the system. So let’s consider the alternative—the sprinkler system. In this method of irrigation, it’s easier to control the water and more efficient since the water’s directed only on the plants. But, in hot climates, some of the water can evaporate in the air. Still, the main problem with sprinklers is the expense for installation and maintenance because there’s a very complicated pipe system and that usually involves a lot more repair and even replacement of parts, and of course, we have to factor in the labor costs in feasibility studies for sprinklers.