Vines grown in California are generally depicted in beautiful scenes at a large winery in Napa, California or along the Central Coast with temperate climates and rolling hills. What most fail to see, are the vast acres of flat vineyards planted in the Central Valley of California dedicated to grape and raisin production. In 2014, California had about 928,000 vineyard acres. Wine Grapes hold the highest share of acreage for the state with 615,000. Raisins, which are almost exclusively grown in the Central Valley, had 192,000 acres. Table grapes, mostly grown in Fresno, Tulare, and Kern County, held about 121,000 acres. California is responsible for 99% of the grapes grown in the United States.
- Currently, vines in the Central Valley are under attack, not by the media like almonds, but rather the growers who are looking to replace them with a higher grossing crop.
- Raisins return about $1,500 per acre when yields and price are good, wine grapes in the Central Valley generally gross $3,750 per acre with good production, and table grapes can return very high profits, but establishment costs are extremely high because of inputs and trellis systems. Grapes grown for raisins yield around 10-12 tons to the acre average, but because of “drying-down” the grapes to make the raisins, there is a yield loss of about 4.1-4.5 times making actual yield around 2-3 tons/Ac. Wine grapes in the Central Valley are not dried down so there is no shrink, but rather than bringing in $1,600 per ton that raisins earn, “green” grapes are paying around $250-$300 per ton currently from the wineries.
- Central Valley wine grapes are used in cheaper wines and are generally mixed in tanks to help producers increase overall volume without having to purchase grapes that are more expensive.
- Table Grape yields are measured in 19 pound boxes in the industry, with the average vineyard yielding 800-900 boxes per acre, with an average of $12-14 per box. This makes table grapes the highest grossing type of grape in the Central Valley, but as mentioned earlier, the development cost on table grape vineyards is extremely high.
- Drip Irrigation is allowing growers to take a “water risk” and plant almonds in place of vineyards despite an ongoing drought and uncertain water supplies. Drip Irrigation is certainly changing the landscape of agriculture in the Central Valley.
Grape and raisin production:
1 Year old Table Grapes w/ Amnon 1.06 GPH @ 42”
- Spacing: Vines in the Central Valley are grown many different ways based on variety of grape being grown, cultural practices and what the grape will be used for after harvest. Common spacing across the Central Valley include, but are not limited to: 10’ x 6’, 11’ x 7’, 12’ x 8’.
- Irrigation: Historically, Thompson Seedless vines planted across the Valley were used in raisin production and always flood irrigated. Today, many vineyards, no matter the crop use or management, are being drip irrigated. Many growers have faced limited water supplies because of the ongoing drought. Vines are much more water “friendly” than almond orchards, which is the crop that has been replacing many vineyards because of production value. Vines use about 2 to 3 acre-feet of water per season, while almond orchards use over 4 acre-feet. Vineyard drip irrigation generally has a single-line that is hung above the ground 18”-24”, with emitters every 36”-42” depending on the vine spacing. Most emitters are in-line today, with flows that range from .42 GPH-1GPH depending on available water, management practices, and type of soil.
A drip irrigation example for table grapes would look similar to this:
- Vines planted 10 feet between rows 7 feet between plants in-row. One line of emitters in hung above the base of the plants with Amnon 1.06 GPH drippers spaced 42” apart, resulting in an application rate of .049”/Hr. With an assumed daily ET of .29 inches, a 5.79 hour irrigation set would be required to match ET for the day. This system would require 22 GPM/Ac. to operate. (Most vineyard systems across the Valley are designed and operated around 10 GPM/Ac.
Jain Irrigation products most likely to be used:
- Amnon—18 or 20mm, 36” or 42” spacing, .42, .53, .61 or 1.06 GPH – One line per row
- TopDrip—18 or 20mm, 36” or 42” spacing, .42, .53, or .61 GPH – One line per row
- Click TIF—Emitters spaced 36” or 42”, .5 GPH or 1 GPH