drip irrigation, a form of irrigation in which water is applied literally as drops to each vine from a pressure-reducing plastic device (the dripper) attached to a plastic pipe. The technique was developed in Israel and Australia in the 1960s, and has been widely adopted wherever irrigation is permitted. Drip irrigation has transformed viticulture since, unlike flood irrigation, it allows irrigation of vineyards on undulating land, and uses a limited water supply to maximum advantage. The technique requires extensive filtration of irrigation water and now soluble fertilizers can be added directly to it, a process known as fertigation. Refinements include burying irrigation lines, which usefully reduces evaporation from the wet soil surface (and has obvious applications in regions where irrigation is prohibited).