Instead of flooding a field, drip irrigation uses thin pipes laid along each row of plants. Small openings in the pipe — called drippers — let the water out slowly, drop by drop, right at the foot of every plant.
Because the water goes straight to the roots, very little is lost to the sun, the wind or running off the ground. The soil between the rows stays drier, so fewer weeds come up there, and the leaves stay dry too, which helps keep many leaf diseases away.
Every plant in the row gets about the same amount of water, so the whole crop grows more evenly. That matters on a hillside, where water poured from above would simply run down the slope.
The same pipes can carry plant food mixed into the water, a little at a time, so the plants are fed steadily instead of all at once. Drip lines take care to set up and the drippers must be kept clean, but they save water and give a steadier harvest.