The term sustainable means different things to different people. And that’s the problem, according to Jim Stollberg, whose company, Maverick Farming Company, Santa Maria, Calif., manages about 450 acres of wine grape varietals in Santa Barbara County.
To clear up the confusion, he enrolled this year in the Sustainability in Practice (SIP) Vineyard Certification Program, developed by the Central Coast Vineyard Team, a non-profit grower group based in Paso Robles. The program requires growers to meet a rigorous standard of operations, in such areas as enhancing biological diversity, reducing soil erosion and conserving water. Performance is verified through extensive records review and a site audit conducted by an independent inspector.
“To say that you are an SIP-certified shows buyers of your grapes that the types of practices you use are well-defined and fall within specific limits, for example, the various pesticides you are allowed use,” Stollberg says. “This can give you a competitive edge. Also, the wineries can use that certification to distinguish their wines from others in marketing them to consumers.”
Enrolling in the program has allowed him to get credit for most of the practices he’s already been doing, since they meet SIP standards.
For example, Stollberg has been using soil sensors to improve irrigation efficiency for the past eight years. He uses soil moisture sensor readings, evapotranspiration data from a California Irrigation Management Information System (CIMIS) weather station and degree days information from the CIMIS web site to calculate water use per vine.
“All this information may show that the vines should be using 10 gallons of water per week to prevent over- or under-stressing them,” he explains. “I can compare this to our actual irrigation rates to see if I’m using water most efficiently, or if I need to increase the frequency of irrigation or the amount of water applied in each set.”
However, this information alone doesn’t tell the whole story, he notes. “Nothing takes the place of walking the fields and seeing what is going on with the vines,” he says. “It can help you find any missing pieces in your irrigation management puzzle.”
For instance, he may see that the angle between the petiole and leaf blade on vine is too small. That would indicate that the vine is being stressed for water, even though the sensor and weather information showed the opposite. That might indicate the need to check the sensor to see if it’s reading correctly. Or, he may need to move it to a different location that better represents the amount of water available to the vine.
Stollberg spends about two hours each week at his computer figuring the most efficient irrigation sets for each of his blocks of grapes for the next week. Then, he meets with his irrigation crews to schedule and fine tune the irrigations.
Improving irrigation efficiency also reduces disease pressures. Too much water can increase leaf size, leading to more shading of the clusters and restricting air flows. This can heighten the potential for powdery mildew and botrytis. “Providing vines only the water they need minimizes the amount of hand manipulation we need to do to maintain the right amount of canopy,” he says.
The number of sensors he places in a vineyard is based on the number of soil types and grape varieties. A 200-acre block with two varieties may have four sensors. The same acreage with the same two varieties but with six types of soil may have six sensors. In each case, these sensors may cover about 80 percent of the vineyards.
“Each costs money, so you need to limit the number,” Stollberg says. “Also, you don’t want to be overwhelmed with data. Having the right information and the ability to understand it quickly is important.”
His approach to water conservation, takes time, he admits. “But, over the long term, we’ve saved money by pumping less water and the quality of our grapes has improved.”