There are four main types of irrigation: sprinkler, surface, drip, and subsurface. Sprinkler irrigation is the most common type, and it involves using a system of pipes to deliver water to the plants. Surface irrigation is the second most common type, and it involves using a series of ditches or furrows to direct water to the plants. Drip irrigation is the third most common type, and it involves delivering water directly to the roots of the plants through a system of emitters or drippers. Subsurface irrigation is the fourth and least common type, and it involves delivering water to the roots of the plants through a system of underground pipes.