Napa Valley Grapegrowers Report: Exploring alternatives to traditional agricultural burning | Agriculture


Beautiful and alluring acres upon acres of vineyards along the valley floor and up to the mountains attract many to the Napa Valley to live, work and visit, and while the tourist economy is going strong it has become increasingly challenging to live and work in the area, motivating many growers in the region to explore alternatives to traditional farming.

Of significant importance to growers is how best to plan for and incorporate sustainable alternatives to traditional agricultural burning in vineyard management. Health and climate change concerns are a crucial part of reevaluating and renovating outdated farming practices.

There is clear motivation to implement innovative, community-based solutions to minimize effects on air quality from various sources including transportation, building energy use, wood-burning stoves and agricultural practices. And after devastating wildfires that have rocked the region and a significantly dry year, growers have more reason to invest in alternatives to traditional agricultural burning.

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For folks outside of the industry, it may be difficult to understand why agricultural burning is a necessity and some would prefer to do away with it altogether.

This has been exacerbated lately by the increase in burning taking place overall — not only in vineyards — but also by fire departments and foresters conducting prescribed burns to clear risky trees and brush, reducing fuel loads on properties throughout the county. That is, the smoke has now also become a side effect of important fire prevention efforts taking place that may be sometimes confused with agricultural burns.

It may also appear as though agricultural burning is conducted without any oversight and perhaps is considered more of a nuisance than it ought to be. In fact, agricultural burning serves a very important role in vineyard management. Regulated by the Bay Area Air Quality Management District, growers must always comply with the state’s standards on how and when to burn and must also work with local fire departments in anticipation of burns.

One of the most important reasons to burn vines is that it is the only effective disposal method of vines with pest and disease issues that prevents further spread.

In Napa County, insect trapping programs routinely monitor for European grapevine moth, glassy-winged sharpshooter, vine mealybug, exotic fruit flies, gypsy moth, Japanese beetle, and western grape leaf skeletonizer. These pests can have devastating effects on winegrape crops and can easily hitch a ride on garden nursery plants, equipment, and green waste material.

The effects of the European grapevine moth were not well known when the pest was first found in Napa County in 2009 with a total of only five moths detected in insect traps. In 2010 there were more than100,000 moths detected and quarantine regulations put in place, with quarantine regulations extended to 10 counties throughout California in 2011.

Insect traps and pheromone twist ties were even deployed to gardens and trees at apartment complexes, business centers, and individual’s homes in hopes of detecting and controlling the spread. After spending over $100 million in public and private funds and intense collaboration between growers and departments of agriculture, the USDA declared the European grapevine moth officially eradicated in 2016.

Agricultural burning in the vineyards may include the burning of pruned vines, burning of all removed vine material to prevent the spread of pests like the European grapevine moth and disease, as well as removed vines for crop replacement.

Crop replacement can facilitate improved sustainability in vineyards including transitioning to drought-tolerant rootstocks, row spacing that facilitates greater use of cover crops, or row orientation that maximizes the use of natural resources while protecting grapes from sunburn.

These types of changes sequester carbon and reduce the amount of irrigation needed. With more emphasis on climate and habitat implications of farming, growers are now interested more than ever on how to improve burning techniques and exploring alternatives to traditional agricultural burning.

That’s where the Napa Valley Grapegrowers  Vineyard Burning Task Force has stepped up to offer growers a guide to reduce harmful smoke plumes. Since November 2015, the NVG Low-Smoke Agricultural Burning Program has set an example of how growers can make an immediate and sustainable difference in the way that they conduct agricultural burns. In its first year, the NVG Vineyard Burning Task Force developed a technique that promotes proper vine drying times, removal of excess dirt, careful lighting, and tarping to keep the center of the piles dry during rain events. The result is a virtually smoke-free burn.

In this way, the NVG Low-Smoke Agricultural Burning Program goes beyond current regulations, to guarantee a virtually smoke-free burn. The NVG Vineyard Burning Task Force has also hosted field days in both Spanish and English with demonstrations on this protocol and is also analyzing current regulations and looking to compare alternative methods of vine disposal and their associated costs and ramifications.

To map out the potential advantages and disadvantages of each method, NVG is pursuing science-based, data-driven answers to questions including whether certain methods sequester more carbon, or simply change the ways in which greenhouse gases are emitted.

For example, another alternative method to traditional agricultural burning is chipping. Benefits over traditional agricultural burning include the ability to use chipped vines for erosion control and mulching that could help with soil health and water retention in the vineyard while eliminating smoke.

However, proper carbon accounting of this method should also factor in the effects of trucking in a chipper, lengthy use of machinery, and hauling woody debris to new locations if not used on site. There are also other obstacles to chipping such as the cost of the equipment, the need for proper training and intensity of the labor required as well as increased safety risks that have limited widespread adoption of this practice.

Comparatively, NVG’s Low-Smoke Agricultural Burning Program:

• guarantees a virtually smoke-free and climate-smart alternative that reduces CO₂ release and spread of particulate matter to preserve air quality

• provides a less labor-intensive alternative for workers than chipping, which requires removing stakes and trellising before disposal

• is cost-effective for companies

• effectively prevents the spread of pests and diseases

Other alternatives to traditional agricultural burning are simply more innovative burning techniques, including the use of air curtain burners and biochar production.

Again, carbon accounting of these methods should factor in effects of equipment and hauling emissions and smoke emissions, but they present growers with the opportunity to return the final result of the burns to the vineyards as a soil amendment, with biochar, in particular, offering the potential for carbon sequestration and water retention.

There is no one right answer or simple solution to any sustainable best practices question, but as responsible growers and good neighbors, pursuing best practices that complement and protect the unique environment and natural resources found in Napa Valley is of the greatest concern.

The NVG Vineyard Burning Task Force is continuing its work with growers to reduce the amount of smoke generated in Napa Valley vineyards, focusing on education around best practices as well as information on sustainable alternatives. The benefits in the vineyard of implementing alternatives to traditional agricultural burning have so much potential and promise!

Napa Valley Grapegrowers’ brochure on Best Practices for Low-Smoke Agriculture Burning can be found In English and Spanish at napagrowers.org.

Napa Valley Grapegrowers represents 685 Napa County grape growers and associated businesses. For more information about the Napa Valley Grapegrowers, visit www.napagrowers.org.

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