- Dry farming refers to crop production without irrigation. Dry-farmed crops rely on the moisture held in the soil from natural rainfall to meet their water requirements for growth. 
- For over 10,000 years of grape growing, dry farming was how grapes were grown. Irrigation practices for grape farming were only introduced to California in the 1970’s. 
According to one study, dry farming is shown to save 16,000 gallons of water per acre annually. 
Dry farming leads to lower crop yields for farmers (which usually means lower profits), making it a significantly less common practice in the US. In California, while exact figures aren’t known, one estimate is that less than 1% of the 600k acres of California vineyards are dry farmed. 
Irrigation often encourages roots to stay near the surface where there is water. Their roots usually only grow 2-3 feet deep. Dry farming, on the other hand, encourages roots to dig deeper to search for their own water. Vines absorb much of their nutrients through bacteria in the soil, so the more surface area of soil they are exposed to, the more nutrients they can absorb. And the deeper the roots grow, the more diversity of soil microbes they reach. 
Dry farming and correlated water deficits have been shown to enhance grape polyphenol production, whereas irrigation and higher water doses reduce phenolic content of finished wines. Dry farming also has been shown to result in thicker and heavier skins, correlating to higher anthocyanin concentrations. 
- Because irrigation can increase grape size and yield but give a lower quality juice, the practice of irrigation is strictly regulated in Europe based on the time of year, method of irrigation, and amount of water allowed.