Other vineyards have seen improved
vine vigor and yield with compost applications. Bob Pestoni of Upper Valley
Recycling (St. Helena, CA), producer of Harvest Compost, contracted with Dr.
Paul Skinner of Vineyard Investigations to study the effect of his compost on
vineyard yields. Skinner compared the effects of compost to a control (no
applied soil amendments) in Robert Mondavi Winerys Tokolon Z block of
Cabernet Sauvignon on St. George rootstock.
After three consecutive years, the
study at Mondavi found that blocks with compost applied had increased yields of
up to 0.9 tons per acre, while the fruit quality remained the same. Application
rates for the study ranged from two to eight tons per acre with the 0.9 tons
per acre increase in yield occurring in the eight-tons-per-acre
Cost of the compost at $24 per ton
applied at Tokolon was recovered by an increased yield valued at $1,350 per
acre. Since the trial ended in 1995, about four tons per acre of compost has
been applied annually to 20 acres in Mondavis Tokolon vineyard.
In addition to annual applications,
Skinner also promotes the use of compost to prepare land for new vineyard
plantings. I typically recommend a pre-plant compost application of five
to 20 tons per acre, depending on the results of our Terrior soil
analysis program. Compost is a good source of trace elements and enhances soil
structure, says Skinner.
Pestoni is in a unique position
because, in addition to being a compost producer, he owns Rutherford Grove
Winery. When asked what application rate he suggests for compost, Pestoni
responds, You have to know your soil. Work with a soil specialist and get
a lab analysis. Then we can talk about application rate. Upper Valley
Recycling does extensive lab analysis on its Harvest Compost and provides
potential customers with the results upon request.
Mulch used for
While many vineyards use straw or
cover crops for erosion control, mulch made from urban yard trimmings can be a
cost-effective alternative. Mulch is usually used for erosion control, weed
suppression, and water retention. Compost improves soil tilth, adds beneficial
microorganisms, and may be used as a slow-release source of nutrients. Mulch
consists of yard trimmings that are ground and then screened to a uniform
particle size. Unlike compost, mulch does not undergo extensive processing to
decompose the material and is, therefore, usually less expensive. It is
generally applied as a top dressing and slowly decomposes over time.
UC Cooperative Extension advisor Ben
Faber in Ventura County has been conducting a demonstration study to examine
the effectiveness of mulch and cover crops for erosion control in lemon
orchards. Preliminary results indicate that both mulch and cover crops
are effective as weed suppression and erosion control methods, reports
Faber. As vineyards continue to expand onto hillsides, mulch is a feasible tool
for erosion control. Vineyard managers may want to experiment with a minimum
mulch depth of three inches; if applied at a six-inch depth, the material will
likely last for at least two seasons.
compost effective for vineyard weed control
Clyde Elmore, a UC Cooperative
Extension weed advisor, recently spoke at Foothill Grape Day in the Placerville
area regarding vineyard floor management. Although he focused on herbicides,
Elmore also discussed his research on the use of mulch for weed control. From
his trials, Elmore concluded, Greenwaste wood chips give good weed
control. The mulch was persistent in the field and should give long-term
weed-control benefits. Because it may last for more than one season, the
short-term direct cost is not the best way to evaluate this product.
However, many perennial weeds such as field bindweed are not controlled well
with organic mulches. Depending on the coarseness of the mulch, two to six
inches of material is needed to control most annual weeds.
At Pina Vineyard Management, White
applies compost for weed control in his vineyards. He is perfecting a vine row
applicator with the hopes to suppress weeds with compost application right next
to the vines. We find this is the most effective way of applying the
compost. The chute will deposit the compost right where we want it and give us
a more concentrated application than broadscale spreading.
Asking questions of compost and mulch
producers and reviewing lab analysis results are the only ways to learn exactly
what youre getting. Common ingredients, or feedstocks, for compost and
mulch include yard trimmings (collected at city curbs or transported directly
from landscapers), manure, and in grapegrowing regions, grape pomace. Any
reputable producer will disclose its feedstock. Producers registered with the
California Compost Quality Council (CCQC) are required to disclose feedstock,
pH, and a number of other product characteristics.
All large-scale producers of compost
are subject to composting regulations promulgated by the California Integrated
Waste Management Board. Depending on their composting method, these producers
are required to maintain the compost pile at a temperature of at least
131° F for a specified number of days. This time and
temperature process kills pathogens and weed seeds. In addition,
regulated producers must test their end product to ensure that certain heavy
metals and pathogens are within acceptable limits.
Producers of mulch, which is ground
wood chips made from orchard or tree prunings or yard trimmings, are not
subject to the regulations and thus are not required to put the material
through the time and temperature process. However, some producers
will subject the material to this process for a minimum time to kill pathogens
and weed seeds, but not long enough to fully decompose the material.
Most producers also obtain product
analysis which shows NPK, pH, and other characteristics of interest to growers.
Martin Mileck of Cold Creek Compost (Ukiah, CA) sells compost to vineyards as a
diverse source of nutrients. I estimate theres about $60 worth of
nutrients in one ton of our compost and it sells for $28 per ton (fob Ukiah,
CA), a fraction of that cost, says Mileck. While nitrogen content of
compost varies, depending on the feedstock, Milecks product typically has
between 1.5% to 2% nitrogen. Mileck also cites the high potash content (about
2.5%) of his product, which results from the addition of wood ash. Wood ash can
also be a good source of other micronutrients.
If producers dont have what you
want, ask if they can get it or make it. Material can be screened to specific
particle size, small or large. In addition, many producers will make custom
blend products upon request. Norm DeLeuze of ZD Wines in Napa Valley wanted a
compost higher in nitrogen than the yard-trimming compost normally produced by
his supplier for his vineyard in the Carneros district.
Greg Kelly of Napa Garbage Company
responded to DeLeuzes needs by adding manure to the feedstock, increasing
the nitrogen from 1.59% to 2.19% and increasing the phosphorus from 0.29% to
1.4%, producing a more balanced, higher quality compost. DeLeuze was satisfied,
and Kelly is now selling the new product to other grapegrowers in the
To locate a supplier near you in
California, call the Waste Board at 916/255-2410 to request the Compost
and Mulch Source List.
Making your own
A number of wineries compost their own
pomace which solves a waste management issue and produces a valuable
end-product. While some wineries use pomace as the only feedstock, a
higher-quality compost may result from adding other feedstocks to the mix of
organic materials.Yard trimmings, old animal bedding, and manure are good
additions to pomace. These additional feedstocks serve as bulking agents and
may help to buffer the pH of the pile. Another option to raise soil pH is to
Those who make their own compost
should be familiar with properly using the basic turned-windrow
technique. The most common composting problem is failure to turn the windrow
(pile) frequently. This causes the pile to become anaerobic and encourages
undesirable microorganisms and produces unpleasant odors. The windrow should be
kept about as moist as a rung-out damp sponge and turned regularly. The more
frequently the pile is turned, the faster the compost will decompose. However,
less frequent turning saves labor and energy.
To obtain sufficient pathogen
reduction and to kill weed seeds, a minimum of three turnings is required in
the 1-2-3 turnover method, advises Bakx, who developed the method. Allow
five days or more between turnings. Depending on the composition of the
material and the particle size, three turnings will result in compost in five
to eight months. Turning six to eight times will produce a finished compost in
three to five months.
Its helpful to obtain a compost
thermometer and monitor the internal temperature of the pile. The pile should
be between 131°F and 150°F for at least 15 days. If the pile exceeds
155°F, turn the pile to dissipate the heat; adding additional water may
result in even higher temperatures. Preventing the pile from reaching 160oF
helps maintain the desired beneficial microbes and also helps prevent
spontaneous combustion from occurring.
While the Waste Board encourages
on-farm composting, current composting regulations may govern agricultural
composting in certain situations. On-farm composters who use only agricultural
commodities (e.g., grape pomace) as feedstock are not subject to regulatory
oversight if they sell or give away no more than 2,500 cubic yards of compost
annually. If they are mixing non-agricultural source material such as yard
trimmings with pomace, on-farm composters may be subject to nominal
Check with your local enforcement
agency (LEA), usually the county environmental health department, for
clarification on any requirements before composting any non-agricultural source
materials. Look for California Code of Regulations, Title 14, Chapter 3.1.
California growers seriously considering on-farm composting may contact this
author for more information and request a copy of the On-Farm Composting
A beneficial practice to consider
If your vineyard could benefit from
improved soil structure, added beneficial microbes, improved moisture
retention, and better erosion control, consider making or purchasing compost
and mulch. Compost and mulch can be important long-term investments in the
health of your vineyard.
Christy Porter promotes the use of
compost and mulch in agriculture for the California Integrated Waste Management
Board. She specializes in the area of compost use in vineyards and can be
reached in her Sacramento office at tel: 916/255-2410 or by e-mail at