In the last article, I gave an overview of our challenging water situation. This article will discuss tools and strategies for dealing with water shortages. The tools I’ll discuss are insurance, conservation, unregulated water sources, storage and rootstocks. Let’s start with storage.
Increasing storage capacity is one obvious way to increase a vineyard’s ability to function during a drought. The key issue to consider right now is that, if you fill your storage from permitted diversion of water from an affected watershed, like the Russian River, Eel River or Tule Lake, your source is likely to be cut off by the state through diversion curtailments. Water collected prior to diversion curtailments, however, will not need to be released. Penalties for violating a curtailment order, I believe, are $2500, plus $1000 per day. If you rely on diversion permits, you should be keeping your storage full for now, in anticipation of curtailments.
Our industry does a great job of conservation and I don’t think I need to tout the benefits of drip irrigation. There are still two areas in which we can still make progress: watering based on monitoring data and dry farming. I’m no expert on dry farming, but if you think you have a site that is conducive to it and can get prices to offset the low yields, you should consider it.
For everyone else, though, the time has come to properly monitor how much you actually need to irrigate to achieve the soil water levels appropriate to your vineyard and strategy. Proper monitoring means you won’t start irrigating earlier than you need to, more regularly than you need to or more heavily than you need to. Many farmers simply look at their vines and water by feel. Though phenological monitoring is necessary, using this as the only source of information on watering decisions is a good way to end up watering too little or too much, too much or too late. The most common method of gathering data for making watering decisions is to use CIMIS data and do a crude evapotranspiration decision based on a weather station near the vineyard. Others use NDVI imaging, neutron probes or other technology to improve accuracy.
Nowadays, however, there exist two new technologies that provide accurate data for your own vineyard, with minimal use of labor. These include Aquacheck probes and surface renewal machines. Surface renewal is a technology that has seen a great deal of research from UC Davis and Hebrew University in Jerusalem. It basically replicates the accuracy of a lysimeter or eddy machine’s evapotranspiration measurements. The former tools cost over $10,000. The surface renewal device costs about $500. These devices monitor actual evapotranspiration rates in the vineyard, which are then cross-referenced with the CIMIS data to determine how much water is needed to accomplish the desired level of irrigation.
Aquacheck probes one-up the surface renewal method by tracking data in real-time and providing mobile access, allowing vineyard managers to actually see how much water is available at any given time, whether they’re on the vineyard or not. The other advantage is that they take measurements at multiple depths. The advantage here is that water in the root zone can be compared to water at other depths. If the wettest point is below the root zone, the vineyard owner knows he’s wasting water. The most basic system’s cost starts at about $3500 and subscription services for mobile monitoring cost around $75 per month.
Whichever method is chosen, vineyard owners and managers should start measuring soil water now, if they don’t already, and strive for accurate measurements to conserve water.
Ever since AxR rootstock was found to be compromised, more plantings have gone in on rootstock that is not particularly drought-resistant. This drought should restore focus on the importance of drought-resistant rootstock. Many North Coast growers know that 110R, 1103P and 420A show decent drought tolerance, but other rootstocks may be worthwhile. For instance, Freedom, Harmony, 5C and 5BB are all drought-tolerant. In some situations, 140Ru and 420AMgt may be useful. Each rootstock represents a different intersection of root architecture, hardiness in drought conditions and vigor. The short takeaways here is for anyone putting in new vines to do his research and make sure he has put enough emphasis on drought-tolerance when picking out rootstock.
Insurance, of course, is the most obvious mitigation strategy for drought-related yield declines. The downside is that, if this drought turns out to be a multi-year drought, the insured yields, which are based on a rolling average, will drop. This is particularly harmful, since the way crop insurance works, it costs more to insure yield than price. As price rises, the premium paid per dollar of coverage rises in a direct correlation. As the percentage of yield covered rises, your premium rises at a hyperbolic rate (covering 70% requires more premium per covered dollar of loss than covering at 60% does.) Growers should take this dynamic into account when they look at the possible financial outcomes of a prolonged drought.
Unregulated water sources:
Three water sources are still unregulated: recycled water, groundwater and water that is purchased through water contractors. More recycled water is coming onto the market. For instance, Healdsburg will soon be providing recycled water to growers in the vicinity. Though purchased water will not be regulated, 95% of the water has been taken off the market by the state.
Groundwater is a complex issue, more so than growers realize. You have ownership rights only to percolated groundwater, not to subterranean flow that is “hydrologically linked” to the nearby watershed. What that means is unclear, but it certainly opens up a pathway for the State of California to regulate the use of groundwater. Growers may want to find experts who can evaluate how susceptible their well would be to such attempts and find out if drilling another well would help or if going deeper would help. In any case, California is the only Western state that does not have groundwater regulations, and that is likely to change in the future. Just because you have a permitted well does not mean that you can rely on that water in the future.
My next article will touch briefly on what the state can do as whole to face the challenges of this drought and then I’ll be back to grape price projections. Cheers.