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PNW
CONSERVATION TILLAGE HANDBOOK SERIES
Chapter 2- Systems and Equipment, No. 12, Fall 1988
Conservation
Tillage Considerations for Cereals
Roger
Veseth
The use of conservation
tillage systems, such as reduced tillage and no-till, for cereal production
has sharply increased in the Northwest in recent years. About 36 percent
of the 1987 cereal acreage in Idaho, Oregon and Washington was under some
type of conservation tillage, up from 24 percent in 1982. This trend toward
increased use of conservation tillage is expected to accelerate in the
1990's. A major reason for this increase is that producers are realizing
the potential advantages of conservation tillage and the importance of
keeping up to date on new technology to develop and maintain successful
systems.
The USDA Farm Program provides added incentive for producers to explore
conservation tillage systems if they have not already discovered the potential
advantages. The Conservation Compliance provisions of the 1985 Food Security
Act require producers to have a conservation plan approved on their highly
erodible cropland by 1990 and fully implemented by 1995 in order to remain
eligible for USDA program benefits. Although conservation tillage is not
necessarily a requirement in conservation plans, it is one of the most
effective practices for holding topsoil in place and one of the few conservation
options which can also help improve production efficiency.
A substantial part of the new technology for conservation tillage systems
in the Northwest has been developed through the STEEP (Solutions To Environmental
and Economic Problems) research program. Over 100 scientists from the
universities and USDA-Agricultural Research Service in Idaho, Oregon and
Washington have been involved in this cooperative, federal-state research
effort since 1975. STEEP and related research efforts have accelerated
the development of new technology for more efficient farming systems which
effectively conserve soil and water resources.
Why Consider Conservation Tillage?
Potential Advantages
There are numerous potential advantages of conservation tillage:
- Improved Production
Efficiency - The potential for reducing production costs is one
of the most commonly reported reasons producers give for changing from
conventional to conservation tillage. Reducing the number of trips over
the field saves fuel, time, labor costs, and machinery wear and maintenance.
- More Timely
Planting - For both winter and spring cereals, yield potentials
typically decline as planting dates are delayed past "optimum seeding
windows" for each particular area. With fewer tillage operations,
more timely planting is often possible with conservation tillage, providing
for a potential increase in yield. However, in areas where wet soils
are a problem in the spring, more surface residue may delay soil drying
and potentially cause delays in spring seeding.
- Increased Soil
Water Storage - A higher yield potential, as the result of increased
soil water storage, is an important advantage in lower and intermediate
precipitation areas. STEEP research has demonstrated that surface residue
commonly increases overwinter soil water storage about 20 percent through
reduced runoff and evaporation compared to low-residue conventional
tillage. Each additional inch of available water increases wheat yield
potential by 5 to 7 bushels. Consequently, where 10 inches of precipitation
occurs overwinter, a 2-inch increase in soil water storage could increase
yield potential roughly 10 to 14 bushels if water is the major yield-limiting
factor.
- Soil Productivity
and Water Quality Maintained -One of the most obvious advantages
ii maintaining soil productivity by effectively reducing erosion. STEEP
research points out that present-day yields would often be 25 to 50
percent higher on many areas of eroded cropland in the Northwest if
erosion had been controlled. The research also demonstrates that maintaining
more crop residue on the surface with conservation tillage can reduce
soil erosion by 90 percent or more depending on the surface residue
level, soil roughness and other factors. When soil erosion and surface
runoff are effectively controlled, the potential for surface water pollution
is also greatly reduced. Pacific Northwest Extension Bulletin PNW 275,
Effective Conservation Farming Systems, describes the runoff
and erosion control potential of several conservation tillage systems.
Potential Disadvantages
Conservation tillage also has potential disadvantages. Because
of the extreme variations in Northwest cropping regions and individual
grower equipment and management, the obstacles to developing successful
conservation tillage systems will vary greatly. There are, however, some
disadvantages which are commonly encountered.
- More Complicated
Management - One of the biggest disadvantages of conservation farming
systems is that they are often more complicated than intensive tillage
systems. In order to take advantage of lower production costs and/or
improved production efficiency, producers must make a special effort
to search for the information they need to put together a successful
crop management system. This can be a big obstacle for growers who are
new to conservation tillage and are not sure where to find needed information.
Growers also need to make a commitment to keep up to date on new developments
in technology.
- Potential Additional
Equipment Expense - Additional equipment expense is possible, but
often not necessary. Some conservation farmers have made significant
financial investment in equipment modification or purchase, while others
have only made adjustments in how they use their present conventional
equipment. Minor modifications or attachments for combines are usually
desirable to eliminate straw and chaff rows.
- USDA Commodity
Program a Greater Obstacle -Crop rotation is often more important
for controlling some diseases and weeds in conservation tillage than
in conventional tillage. Consequently, USDA commodity acreage-restriction
programs may be more of an obstacle for conservation farmers than for
conventional tillage farmers in some areas because of the constraints
they place on flexibility in crop rotation. For example, the inclusion
of a spring barley crop to lengthen 2-year rotations, such as wheat-pea
or wheat-fallow, to 3-year rotations can be restricted by lack of sufficient
barley base-acreage and the potential loss of wheat base.
- Greater initial
Risk - Trying anything new for the first time creates uncertainty.
When growers make a major change in management practices, there can
be an initial risk that yields may not be maintained because of unforeseen
problems. As they gain experience and confidence with conservation tillage
practices on their own farm over time, the risk level declines. Bankers
and lending agencies can have a high level of risk aversion, thus limiting
the flexibility and options of producers wishing to explore conservation
tillage.
Some Key Crop
Management Considerations
Knowledge of Pests
The first step in controlling weed, disease and insect problems is
to develop a basic understanding of each major crop pest you encounter
in your area. What is its life cycle? What conditions affect its survival
from year to year? What are its "weak links" that can be capitalized
upon for control through -op management options? This does not mean that
producers will need university degrees in plant pathology, entomology
and weed science, but it may mean reading some Extension publications
or possibly attending some conferences that address pest problems in their
area. If producers do not have a good understanding of the pests they
are dealing with, they will probably have a more difficult time developing
successful conservation tillage systems,
Crop Rotation
In conventional tillage systems, intensive tillage has served
as a substitute for other pest management choices, one of the most significant
being crop rotation, Crop rotation is probably the single most effective
pest management tool in conservation tillage. It is particularly important
in reducing the potential for many soilborne diseases of cereals, as well
as other crops. For example, crop rotations with 2 years out of winter
cereals can effectively control Cephalosporium stripe in winter wheat
under conservation tillage. One non-cereal crop in the rotation controls
take-all for the following wheat crop and also helps reduce the incidence
of Rhizoctonia root rot and Pythium root rot in cereals.
Crop rotation is important in weed control as well. For example, control
of winter-annual grass weeds, such as downy brome (cheatgrass) or jointed
goatgrass, is greatly improved by including spring crops in the rotation,
or crops which allow use of grass weed herbicides not possible under winter
cereals.
Combine Residue Distribution
Producers successfully using conservation tillage often list uniform
residue distribution from the combine as one of the first important steps.
Impacts of straw and chaff rows include: drill plugging; poor seed-soil
contact; straw contact with the seed, nutrient tie-up; increased soilborne
disease; a concentration of volunteer and weed seeds, resulting in more
crop competition; reduced herbicide effectiveness; and increased rodent
damage. Commercial straw and chaff spreaders, now available for most combine
models, and farmer shop modifications are often very effective in eliminating
straw and chaff row problems. Pacific Northwest Extension Bulletin PNW
297, Uniform Combine Residue Distribution, provides more information
on this topic.
Fertilizer Application
STEEP research has shown that early root access to fertilizer
banded below the seeding depth and near the seed row often provides more
efficient fertilizer use and increased cereal yield, particularly under
conservation tillage. The advantage of placement can be enhanced or overshadowed,
however, by other factors which influence plant nutrient uptake. These
factors include: soil nutrient level, nutrient mobility, precipitation
level and distribution, soil pH and soil temperature. The greatest response
to fertilizer banding is on soils with low soil-test nutrient levels and
under cold wet conditions. A review of fertilizer placement considerations
for cereal root access in no-till and minimum tillage is available in
Pacific Northwest Extension Bulletin PNW 283, Fertilizer Band Location
for Cereal Root Access in Conservation Tillage.
Seeding Considerations
Using good quality seed of adapted cereal varieties is as important
under conservation tillage as in conventional tillage. Seeding date
and rate can also be important management choices. Seeding date can
significantly influence the potential impacts of several important pests
under conservation tillage. For example, late fall seeding greatly increases
the potential for damage from Pythium root rot, whereas early seeding
can increase the potential for Cephalosporium stripe and strawbreaker
foot rot. Integrated management strategies have been developed through
the STEEP research effort to effectively reduce the potential of many
of the plant diseases encountered, Seeding date can also influence weed
control options and weed potential, particularly with winter annual grass
weeds, depending on fall weather conditions, herbicide options and other
factors.
Seed age can bean additional consideration with seeding date. STEEP research
has shown that in areas with potential for Pythiwn root rot, using current-year
winter wheat seed will reduce the potential for damage with late seeding
dates compared to older seed lots, Under normal or earlier seeding times,
seed age generally did not result in differences in Pythium root
rot because the pathogen is less active when soils are warmer and dryer,
In addition, current-year seed can result in more high-temperature dormancy
problems than older seed with early or normal winter wheat seeding dates
in fallow. The importance of seed age is greatly influenced by storage
conditions.
Seeding rates slightly higher than normal (10 to 25 percent) have commonly
been used in conservation tillage to compensate for less favorable
seedbed conditions. The need for increased seeding rates must be evaluated,
however, for the particular field conditions including: previous crop,
available water; tillage and planting equipment used; final seedbed conditions;
tillering ability of the cereal variety; and other factors.
Herbicide Options
Herbicide options after the crop has emerged are generally the same
under conservation tillage as under conventional tillage, Some preplant
and pre-emergence herbicides which require thorough soil incorporation
will, however, have limited use in conservation tillage. Where these herbicides
cannot be used, other herbicide and management options will need to be
selected for control of the particular weeds. It is always important for
application equipment to be properly adjusted to effectively penetrate
the crop stubble and to ensure weed contact with foliar-active herbicides.
Tillage System and Equipment Selection
The type of equipment producers select for their conservation
tillage system will depend on the individual farming situation. Two important
considerations in conservation tillage are seeding through the surface
residue and applying fertilizer to achieve the highest use efficiency.
A majority of the commercial conservation tillage drills now available
have improved residue handling potential and fertilizer placement options.
Producers are also modifying their drills with numerous commercial attachments
and shop fabrications. Many producers have adapted their own chisels and
cultivators for banding fertilizer in order to reduce the number of field
operations.
Equipment purchases or extensive modifications are often not needed for
effective conservation tillage. A common alternative approach is changing
how conventional equipment is used in order to maintain more surface residue.
Reductions in tillage speed and depth, turning the plow furrow uphill,
removing trash boards on moldboard plows, and other adjustments in equipment
use can significantly increase surface residue retention.
Some fertilizer dealers in the Inland Northwest, such as McGregor and
Wilbur-Ellis, now have fertilizer injector equipment for direct shanking
of fertilizer without prior tillage in ''shank and seed" type systems.
Consequently, producers can now use their standard drills and avoid equipment
purchases or modifications for fertilizer placement under conservation
tillage.
There is no one best tillage system or equipment combination for all situations.
Climatic conditions, available equipment, crop rotation options, soil
type, topography, cash flow, information resources and many other factors
influence producer choices.
Information Resources For Getting Started
Successful conservation tillage requires much more than just fewer
tillage operations, equipment purchases or modifications, or maintaining
more surface residue, It must bean integrated system of crop management
choices affecting crop health and production efficiency.
A big investment you have to make in the transition to conservation tillage
is your time spent pulling together the information you need to understand
and implement a system. Talk with conservation tillage farmers in your
area. Attend educational conferences such as the Eighth Annual Inland
Empire Conservation Farming Conference at the Washington State University
Coliseum in Pullman, Feb. 7, 1989, Contact your local Conservation District,
USDA-SCS Office and Extension Agricultural Agent for information.
Reference materials are also available through the STEEP Extension program,
which is designed to help increase producers' access to new technology
developed through STEEP and related conservation farming research efforts.
The quarterly STEEP Extension Conservation Farming Update provides
in-depth reviews of the latest developments in conservation tillage research
in the Northwest, written from a management perspective.
A major focus of the STEEP Extension program is currently on an early
1989 release of a new Pacific Northwest Extension Conservation Farming
Handbook. This Handbook will be one of the most comprehensive reference
guides on conservation tillage for this region. It will contain more than
110 articles and Extension publications on the latest research developments
in all aspects of conservation tillage management. It will continue to
be updated in the future. To get on the mailing list for the Update
and to be informed when the Handbook is available, contact: Roger
Veseth, WSU/UI Extension Conservation Tillage Specialist, Department of
Plant, Soil and Entomological Sciences, University of Idaho, Moscow ID
83843 (208) 885-6386, or Don Wysocki, OSU Extension Soil Specialist, Columbia
Basin Agricultural Research Center, Box 370, Pendleton, OR 97801 (503)
276-5721.
Developing a conservation tillage system is a big commitment, requiring
a dedicated effort. But, the rewards of improved production efficiency
and resource conservation are well worth the investment.
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