Irrigation is the artificial watering of farmland to help crops to grow where water is naturally lacking. This can be, for example, getting plants to grow in a desert. Deserts are favourite places for irrigation because, if you can get water, there is plenty of sunshine and warmth for growth.

Another occasional when watering is useful is when there is an unusually long period without rainfall. Plants need lots of water when they are growing, and not so much when they are ripening, so irrigation is often done in late spring if rainfall is not enough. Without it, the crop will not give a good harvest.