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Growers implement cover crop programs for a variety of reasons
including erosion control, nutrient re-cycling, and dust control.
New regulations, regarding water quality, provide added incentive
to implement cost-effective cover cropping programs that effectively
reduce vineyard erosion.
New water quality
regulations
As part of the California State Water Resource Control Board’s
(SWRCB) Conditional Waiver for Agriculture Discharge, each of seven
Regional Water Quality Control Boards (RWQCB) must develop a replacement
waiver program that will protect water quality within its region.
The replacement waiver program was created by the SWRCB to replace
the Agriculture Discharge Permit, which expired January 2003. The
old permit allowed growers to discharge water from fields without
restrictions. Each water board is required to develop a replacement
waiver program for growers within its region that addresses the
quality of water leaving agriculture areas.
As part of the replacement waiver program, growers are being required
to complete a Farm Water Quality Plan that addresses several components
of the farming operation and documents future practices to be adopted.
On the Central Coast of California (Region 3), growers can complete
a Farm Water Quality Plan through the University of California Cooperative
Extension, or they can complete the Positive Points System (PPS)
evaluation with the Future Plans Form from the Central Coast Vineyard
Team (CCVT). 1
The PPS evaluation presents a series of yes/no questions and addresses
the “whole farming system” by reviewing six categories
of farming practices. The grower must also document future plans
for improving water quality by implementing best management practices
(BMPs) on a particular site. (the
Positive Points System and the Future Plans Form)
Regardless of which farm plan growers choose to utilize — the
UC Farm Water Quality Plan or CCVT’s Positive Points System
— they must develop a list of BMPs to deal with each of the
four areas associated with irrigated agriculture’s contribution
to Non-Point Source (NPS) pollution: fertilizer, pesticide, irrigation,
and soil management.
Each farm plan must include a list of BMPs that the grower will
employ (or currently uses) to control erosion by reducing off-site
movement of soil and water into nearby water bodies. In many cases,
these are inexpensive and efficient practices that can save growers
time and money.
 Types
of BMPs
BMPs are a combination of management, cultural, and structural practices
that growers can implement to effectively control problems in the
field. In regard to NPS pollution (related to agriculture), one
area of BMPs includes practices that keep soil and water in place,
thus controlling erosion.2
The SWRCB recommends several BMPs to reduce erosion in vineyards.
Four are:
- Cover crops — Cover crops can be planted in vineyards between
vines to control erosion, increase infiltration, reduce soil compaction,
and improve soil tilth, and to add organic matter and nutrients
to the soil.
Cover crops (either annual or perennial) are usually planted in
the fall, following harvest. Perennials or reseeding annuals can
provide long-term protective cover lasting more than three years.
Examples of commonly used cover crops in vineyards include erosion
mixes (including various grass species and annual legumes):
• Zorro fescue (Festuca megulura fast-establishing annual
grass);
• Clovers (Trifolium-legumes including rose clover [Trifolium
hirtum], crimson clover [Trifolium incarnatum], and Persian clover
[Trifolium resupinatum]); and
• Triticale (Triticale hexaploide fast-growing annual).
In addition, cover crops can support populations of beneficial
insects, which is important in promoting biological diversity
within a vineyard.
- Filter strips — Filter strips are planted parallel or adjacent
to vineyards or along waterways to slow and reduce run-off and
remove sediment and pollutants through infiltration. They can
also enhance wildlife habitat when native species are used. Planted
with dense vegetation in areas between five and 10 feet wide,
filter strips can include grasses, such as tall fescue (Festuca
arundinacea), switch grasss (Panicum virgatum), creeping wildrye
(Leymus triticoides), and blando brome (Bromus hordeaceus).
- Tree/shrub establishment — Trees and shrubs are commonly
planted along bare hillsides of vineyards to reduce erosion by
increasing water penetration and infiltration rates. They can
also enhance wildlife habitat. Trees and/or shrubs can be planted
any time during the year, but they may require additional irrigation
if not planted prior to winter.
- Land smoothing — Removing rills and gullies on land surfaces
with earth-moving equipment can reduce erosion and improve water
drainage and water distribution. Land smoothing is usually conducted
prior to planting or construction. The work usually requires the
use of scrapers, land levelers, and backhoes. Land smoothing can
be costly, but most of the time the benefits outweigh the costs.
Smooth land is easier to plant and less likely to erode.3
 Growers
frequently spend significant time and money each year taking corrective
action to mitigate existing problematic field conditions, such as
sediment build-up at the end of bare roads, rills, and gullies and
large amounts of water run-off, which can carry nutrients and pesticides
into nearby fields and water bodies. For example, many growers use
the following techniques every year:
- Sand bagging — Anticipating winter rains, some growers
place sandbags at the bottom of roads and hillsides to prevent
erosion.
- Road re-grading — Every year growers must re-grade bare
roads that were wiped out during the rainy season.
- Sedimentation removal — Large amounts of soil and sediment
can build up at the end of bare roads and hillsides when proper
cover is not placed on a surface. Growers must then remove the
soil every year after the rainy season.
Unfortunately, these costly efforts must be repeated every year,
and they don’t correct the problem. BMPs are longer-lasting
solutions that can save growers time and money.
Clean Water Project
In 2002, the CCVT, a non-profit vineyard grower group on the Central
Coast of California (Monterey, San Luis Obispo, and Santa Barbara
counties), received a three-year Clean Water Act, Section 319(h)
Grant for Water Quality Implementation Projects administered through
the SWRCB. Goals of the grant were to reduce, eliminate, or prevent
NPS water pollution resulting from agricultural run-off and to enhance
water quality in impaired water bodies.
Funds available through the 319(h) program were directed toward
demonstration projects that would achieve these goals.4 CCVT developed
the Clean Water Project to assess and reduce non-point source pollution
from Central Coast vineyards through the implementation of BMPs.
 As
part of the CCVT Clean Water Project, ten demonstration sites were
established at vineyards between Monterey and Santa Barbara counties
to demonstrate the effectiveness of BMPs in reducing soil and water
run-off. For example, a demonstration site was established at a
vineyard in Santa Maria, CA, which was located inland on slopes
ranging from 5% to 15% with Betteravia Loamy Sand, dark variant.
Previously, the vineyard manager had problems with the roads eroding
within the vineyard due to rains and lack of cover crop.
“In years past, we regraded and refilled the sandy roads after
the rainy season,” states Kevin Merrill, vineyard manager.
“Graders, scrapers, and bulldozers were used to smooth the
roads and re-allocate excess soil at the bottom of the roads.”
He estimates that between $10,000 and $15,000 were spent annually
for this work.
In 2003, Merrill (with help from the Cachuma Resource Conservation
District [RCD] and CCVT staff) implemented several BMPs to reduce
soil run-off and to reduce costs. The RCD was chosen for its experience
with local erosion issues. RCD staff helped Merrill select the following
BMPs for the site:
- Smoothing and leveling roads;
- Planting grassed roads; and
- Planting filter strips.
In the summer of 2003, roads were smoothed over an area equivalent
to 10 acres. Gullies and rills were removed. Following harvest,
the roads were seeded to establish cover crop and reduce runoff.
A mix of sheep fescue (Festuca ovina) and hard fescue (Festuca longifolia)
was selected because of its drought tolerance, longevity (as a perennial),
and deep-rooting properties. The fescue mix was drilled along the
roads at 30 pounds per acre (lbs/acre).
Straw was spread on top of the road at one ton per acre (approximately
one to two inches deep) to secure the seeds against the first rains.
In one area more susceptible to erosion, jute netting was secured
on top of the road for additional support to the seeds. Along the
fence beside a couple of roads, triticale was planted as a filter
strip to slow water run-off from the adjacent property. Triticale
was selected because of its early ripening and large yielding capacity
and was broadcast at 90 lbs/acre.
BMP benefits at project sites
Many benefits were evident through implementing selected BMPs along
these demonstration roads: an increase in cover from 10% to 75%,
a reduction in soil leaving the roads, and reduced re-grading expenditures.
Total cost to implement BMPs at this site was approximately $1,500
($150/acre), including seed costs, implementation, and maintenance.
This cost was considerably lower than the approximate $10,000 spent
annually on grading and staff time. In addition, BMP benefits can
last for two to four years.5
At another vineyard in Los Olivos, CA, a demonstration site was
established along a highway on slopes ranging from 9% to 15%. The
area was subject to large amounts of runoff from nearby hills. In
years past, run-off removed Elder Sandy Loam soils from the vineyard
and deposited them onto the road below. Sandbags were placed around
the vineyard before the rains, and then excess soil was removed
from the bottom of the vineyard. Average cost was between $500 and
$1,000 per year.
As part of the Clean Water Project, a 50-acre parcel within the
Los Olivos Vineyard was established as another demonstration site.
Following harvest in 2002, BMPs were implemented to reduce and infiltrate
run-off through the site. Staff from the Cachuma RCD helped develop
a work-plan to determine which cover crops would work best to reduce
run-off and be most cost-effective.
The area was divided into four blocks. One block was drilled with
35 lbs/acre of Perennial Erosion Mix6 of crimson clover, rose clover,
subterranean clover (Trifolium subterraneum), medic (Medicago),
Persian clover, dwarf rye grass, and fine fescues. Another block
was drilled with 35 lbs/acre of Drought Annual Mix (crimson clover,
rose clover, subterranean clover, medics, Persian clover).6 A third
block was divided in two sections. The upper most half of the block
was drilled with 80 lbs/acre of Juan triticale (Triticosecale Wittm).
The lower half of the block was drilled with 10 lbs/acre of Zorro
fescue, as was the fourth block.
Benefits of implemented BMPs were seen in each of the subplots.
The Perennial Erosion Mix grew to heights of eight to 12 inches
and covered about 85% of the planted area. The Annual Erosion Mix
grew six to eight inches in height and covered about 50% to 60%
of the area. Juan triticale grew to 18 to 36 inches in height and
covered almost 90% of the planted area. Zorro fescue grew four to
six inches and covered about 50% of the planted area (lack of better
establishment may have resulted from insufficient rain after planting).
Total cost to implement and maintain BMPs at this site was approximately
$2,000, or $40/acre. This included the cost of seeds, two-thirds
of which were perennial and would re-seed annually up to five years.
In addition, the cost for the Juan triticale (the most effective)
was minimal ($0.30/lb) and could easily be replanted yearly if needed.
In the Clean Water Project as a whole, the average cost to implement
best management practices decreased from $237.76/acre to $170.15/acre
from Year 1 to Year 2 (Table I) for vineyards participating for
multiple years. At some sites, costs remained constant or increased,
due to the type of practices implemented or problems with establishing
cover during the first season. But for the most part, growers were
pleased with the cost-reduction and cost-effectiveness of the practices.
Estimated soil loss reductions
In the second year of the Clean Water Project, CCVT staff worked
with the Templeton Natural Resource Conservation Service staff to
estimate soil loss prevented from demonstration sites using the
Revised Universal Soil Loss Equation (RUSLE) 2.
RUSLE 2 is a computerized model used to plan conservation practices;
it provides an estimate of soil loss in tons per acre per year (tons/acre/year)
that would occur with various practices. The equation considers
five factors: climate (precipitation and temperature); soil type
(series); slope; crop management (equipment used); and conservation
practices (sediment basins, cover crops, etc.).7
By using the RUSLE 2 model, CCVT estimated that, without implemented
BMPs, soil loss ranged from 2.35 to 42.0 tons/acre per year at demonstration
sites. With implemented BMPs, soil loss ranged from 0.21 to 5.75
tons/acre per year. On average, project staff estimated that the
implemented BMPs reduced soil loss by 15.25 tons/ acre per year
(Table II).
Ripple effect
Demonstration projects such as the Clean Water Project help growers
see the specific costs and benefits of implementing BMPs, in addition
to learning the “how-to” for specific practices.
By providing technical assistance and documenting specific project
information, the Clean Water Project capitalizes on the growers’
willingness to adopt new practices and leverages their contributions
of time and resources.
Growers provide a living laboratory that helps develop information
that can be extended to a broader audience. This paves the way for
more growers to adopt similar practices with less risk because of
lessons learned in demonstration projects. With the current Agriculture
Discharge Waiver in place, such lessons will help growers be successful
in adopting BMPs that protect water quality.
Further Reading:
“Conditional
Waiver of Waste Discharge Requirements for Irrigated Lands”.
“Non-Point
Source (NPS) Pollution and Best Management Practices (BMPs)”.
“Central
Coast Vineyard Team’s (CCVT) Clean Water Project (CWP)”
or contact Dawn Stimson; Clean Water Project Coordinator at 805.369.2288
or via email.
California Stormwater Quality Association. (2003). “Vegetate
Buffer Strip.” California Stormwater BMP Handbook, TC-31, California.
Glenn McGourty. “Cover Cropping Systems for Organically Farmed
Vineyards.” Practical Winery &
Vineyard. September/October 2004.
University of California Division of Agriculture and Natural Resources.
(1998). “Cover Cropping in Vineyards, A Grower’s Handbook.”
Publication 3338, Oakland, CA. January 2003.
USDA Natural Resource Conservation Service (NRCS). (1997). “Filter
Strips.” Conservation Practice Job Sheet, 393, California.
April 1997.
References:
1. “Conditional
Waiver of Waste Discharge Requirements for Discharges from Irrigated
Lands.” (PDF) (July 9, 2004).
2. University of California Cooperative Extension and USDA
Natural Resources Conservation Service. (2003). “Farm Water
Quality Planning Short Course — Water Quality Information.”
Estrella River Watershed, San Luis Obispo County, February 2003.
3. University of California Cooperative Extension and USDA
Natural Resources Conservation Service. (2003). “Farm Water
Quality Planning Short Course — Water Quality Information.”
Estrella River Watershed, San Luis Obispo County, February 2003.
4. “319
Program Fact Sheet.” (Document) (2003).
5. Huebner, G. “Forage
and Grass Seed Production Guide 2002” (2001).
6. Seed mixes were purchased from Lockwood Seed and Grain located
in Chowchilla, CA.
7. “Revised
Universal Soil Loss Equation, Version 2 (RUSLE).” (2004).
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