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Using
Fire as a Management Tool
FOR
CROP PRODUCTION IN EASTERN WASHINGTON
Roland
Schirman - Columbia Co/WSU Extension
Producers
in eastern Washington have tried many approaches to maximize their
conservation efforts to provide the greatest protection of natural
resources yet remain economically viable. One of the tools that
has been used, but is often misunderstood by the non-farming public,
is fire to manage crop residue and associated problems.
Used
selectively, fire can be an effective tool for managing residue
and combating diseases, insects and weeds, and be an environmentally
sound Best Management Practice. Land managers across the West have
found the use of fire, as a selectively applied site-specific process,
to be an important tool in protecting the health of the land. The
Nature Conservancy--which uses fire to protect its prairie lands
from degradation--and the National Forest Service are but two examples.
The same is true of agriculture in its application of stewardship
of available resources.
Land
managers utilize many basic biological and physical factors when
choosing use of fire over alternative production tools. Several
of these include:
RESIDUE
MANAGEMENT/WATER CONSERVATION
The
majority of crop production acres in eastern Washington are dependent
on naturally occurring precipitation. To optimize the precipitation
that does occur, producers must intercept and hold the moisture
where it falls, minimize evaporative loss and carefully select other
cropping practices to have moisture available at critical growth
stages of crop development.
When
fire is properly used as a component of "holistic" production
systems, mechanical tillage operations are reduced significantly,
field operations are performed in a more timely manner, formation
of soil compaction layers are minimized, water infiltration into
the soil is enhanced and plants can more effectively use the available
root zone moisture. Cropping systems that integrate fire in spring
crop management plans provide additional benefits afforded by the
ability of growers to leave standing stubble during the winter period
that reduces snow drifting and surface evaporation. Without the
use of the spring burn, fall tillage is required to enable timely
spring planting and must be coupled with excessive numbers of tillage
operations to prepare the ground for planting. Both of these latter
items reduce efficiencies of water management.
RESIDUE
MANAGEMENT/SOIL ERODEABILITY
Nearly
every farm in eastern Washington has highly erodible land. Control
of erosion to preserve farmland productivity has been an ongoing
struggle since this area was first settled.
During
the past 25 years great effort has been expended in an attempt to
develop an economically feasible crop production system for eastern
Washington that allows direct seeding of crops(sometimes referred
to as no-till). One of the identified limitations is the ability
to penetrate the residue and create a suitable micro environment
for timely germination and emergence of the crop when crop aftermath
exceeds several tons per acre. With the use of fire, producers have
been able to implement a direct seeding/low till systems.
Compared
to intensive tillage the benefits of these systems are measured
in:
- Greater
soil aggregate stability,
- Reduced
microbial oxidation of root and associated organic materials,
- Improved
water infiltration with better retention of soil macro pores,
- Retention
of intact plant crowns giving improved soil holding capability,
- Improved
seed germination of spring crops with higher soil temperatures
- Timely
nutrient cycling in relation to crop needs.
PEST
MANAGEMENT
Disease,
insect and weed pests are biological opportunists that can become
economically devastating in cropping systems that use only limited
management options. Unmanaged, these pests can proliferate to economic
loss levels that render the cropping system totally unprofitable.
A producer must interrupt the life cycle of a pest to prevent escalation
of the problem in continuing years.
Three
of the most severe examples discussed below have caused millions
of dollars in losses to dryland cereal gain producers alone in the
Pacific Northwest. In each situation discussed, the absence of fire
as a management tool is documented to have increased the economic
losses from these biological pests. It must be remembered that pest
management is an integrated process with many facets. Fire as a
tool must be a carefully planned component of any management system.
Cephalosporium
stripe, a fungal disease that prevents
nutrient movement to developing winter wheat heads by clogging vascular
tissues, produces infectious spores that remain viable primarily
on the above ground portions of infected plant residue. Spores on
infected residues remain viable for a number of years and can infect
new seedings of winter wheat through root systems and kill developing
tillers. Management of this disease is further complicated by the
lack of registered fungicides for control and difficulty experienced
by plant scientists to develop plant resistance to this complex
disease. Reduction of crop residue with fire when integrated with
other pest management practices such as spring cropping and/or the
use of alternative crops has proven successful in lessening the
occurrence of this disease. Without the use of fire as a management
tool, producers are left with planting more years of non-susceptible
crops with lower economic potentials or using excessive tillage
before the next winter wheat crop to reduce inoculum by "destroying"
the host residues. The latter is extremely devastating to soil conservation
and soil quality enhancements.
Hessian
fly, a major insect problem in
wheat producing regions of the USA, was not a serious threat to
Pacific Northwest wheat production under systems which utilized
intensive mechanical tillage. Tillage which destroyed or buried
residue, also destroyed or buried the overwintering pupae stage
of Hessian fly which could in turn infect subsequent winter or spring
wheat crops. However, with the implementation of soil conserving
- high residue management systems, the overwintering pupae stage
of Hessian fly was left unharmed and began to build to economic
damaging levels in the overwintering straw. This was very apparent
in the early 1990s in the Pacific Northwest, as growers implemented
requirements of the USDA Food Security Act which was initiated 1985.
In contrast to Cephalosporium stripe, some suppression can be obtained
with selected insecticides or resistant varieties; however, the
added cost and or lower yield performance of these varieties places
the growers at an economic disadvantage. Integration of fire
as a management tool help minimize the economic impact of Hessian
fly is considered a component of Integrated Pest Management systems
utilized to combat this serious insect pest.
Weeds
are undoubtedly the most visual example, regardless of cropping
system, of how shifts in management practices cause variations in
ecological adaptations of different weed pests. Each weed has slightly
different ecological requirements and it is the producers duty to
understand the management of the "weed seed bank" of each
field. Jointed goatgrass has become one of the most severe
grass weed species problems in winter wheat cropping systems infesting
over one million acres in the Pacific North West alone. Jointed
goatgrass reproduces only by seed, but seed can remain viable in
the soil for up to five years. There are currently no herbicides
available that will control this weed selectively in winter wheat.
Timely burning of stubble after winter wheat harvest kills about
90% of the seed in jointed goatgrass spikelets laying on the soil.
In the absence of fire as a management tool, the recommended management
practices to manage the weed seed bank is not growing winter wheat
or other winter cereal crops for three to five years. Historically
spring wheat has yielded about two-thirds the grain as winter wheat
placing farmers at a distinct economic disadvantage when more multiple
years of spring crops are grown.
INDIRECT
SAVINGS
Since
the replacement of animal power with petroleum power in farming
operations, agriculture has become a major "consumer"
of non-renewable energy reserves. Fire as a management tool saves
an average of three tillage operations, most of which are power
intensive and high users of non-renewable energy resources. Repair
and maintenance on equipment is also greatly reduced providing further
conservation of natural resources.
SUMMARY
Fire
has a proven history as a "natural" and integral component
of biological cropping systems for centuries. Research scientists
and producers continue to recognize the importance of this "tool"
in current cropping systems and how it needs to be retained as a
selective use option as we enter the Twenty-first Century. Availability
of all cropping tools as components of a "holistic" agricultural
system is critical to the long-term survival of agriculture. More
importantly, we must develop systems that are truly environmentally
designed to protect our most important natural resource -- the soil.
Editorial
note: The use of burn-notill became a NRCS approved practice in
1997. It was socially unacceptable to the opponents of agricultural
burning. A lawsuit ensued and the practice was discontinued as a
NRCS approved BMP. Ed Adams
Agricultural
Sustainability. Highlights from a seminar series conducted by Washington
State University's Ag Horizons Team and funded by USDA Western Region
SARE.
Ed
Adams
668 North Riverpoint Blvd. Box B
Spokane, WA 99202-1662
Phone: (509) 358-7960
FAX: (509) 358-7900
 adamse@wsu.edu
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