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Cover Crops in the Napa Valley

Some Sample Costs for Annual Covercrop Establishment

Casual observation of covercrop establishment practices last fall and winter pointed towards more use of these by growers in the Napa Valley than ever before. Many vineyards were planted successfully to annual mixes sold as custom blends. Others used their own blends of oats, barley, bell beans, and vetch. One trial in the Carneros conducted by Mondavi Winery is looking at annual covers in the vine rows with a different annual blend in the vine middles. Some growers successfully tried native perennial grasses for the first time. That the popularity of cover crop usage in the vineyard has gone far beyond only erosion control is a testament to their acceptance by growers as a useful tool in vineyard fertility management, soil organic matter enhancement, vigor control and insectary development. And of course, the use of cover crops continues to be important for erosion control on hillsides and flatlands. These are a few of the benefits. There are many more.

One of the important questions that growers ask about cover crop development in their vineyard is the cost. Depending upon whether one chooses a perennial or an annual crop, the rate and cost per lb. of seed applied and the method of application and amount of soil preparation can affect the final cost. Another consideration is the row spacing (number of rows per acre). Although most growers do not find the establishment and management of cover crops to be a primary vineyard operational cost, there is some concern that unforeseen problems can raise the cost level unexpectedly. For example more effort in getting rid of the cover crop in the spring through mowing and disking was one such problem experienced in this past season that added to the final per acre cost.

One grower reported that the average establishment cost for barley, bell beans and common vetch mix, planted by drill in the fall of 1997 broke down like this:

Bulk Seed @ $ .33/lb X 100 lbs. per acre =$33.00
* Max Organic Soil Builder

Planting: Tye seed drill and 6030 tractor, 1 pass/middle
8 ft. Rows @ .67 hrs/ac $35.50
9 ft. Rows @ .59 hrs/ac $30.13
10 ft. Rows @ .51 hrs/ac $26.95

Total $ per acre $59.95-68.50


Approximately 1000 acres were planted with this mix. Land preparation usually involves one disking only that can add $25-$30 per acre. Mowing costs are about $15-$20 per acre per pass. Perennial cover crop establishment costs are about the same for drilling but seed tends to be much higher in cost per lb. Perennial native grasses could cost several hundred dollars an acre or more, for seed alone. Water leaving the vineyard was for the most part clear all winter long, indicating very little soil loss. His feeling was that this far outweighed the additional costs of management. His plan is to replant the same cover crop in 1998-99 at a reduced seed rate (75 lbs. per acre instead of 100). He plans to start theproject in early September, as this particular mix will survive periods of drought. Understanding some the costs associated with cover crop management will help the grower decide whether the benefits outweigh the inputs. Although there may be management difficulties, use of cover crops in the Napa Valley will likely remain an important and useful tool for the vineyardist as we learn more.

(written by DeWitt Garlock)

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