Aerial Seeding

Application of plant seed to burned slopes by aircraft.

Purpose: Aerial seeding, usually grasses but occasionally also legumes, is carried out to increase vegetative cover on a burn site during the first few years after a fire. It is typically done where erosion hazard is high and native plant seed bank is believed to have been destroyed or severely reduced by the fire. Seed is applied by fixed-wing aircraft or helicopter.

Relative Effectiveness: Excellent-24% Good-28% Fair-28% Poor-20% (Replies = 83). Interviewees were almost evenly divided on the effectiveness rating of aerial seeding, with a slight majority regarding it as either "good" or "fair". Respondents in Regions 1, 4, and 6 were more likely to rate seeding "excellent" or "good" than respondents in Regions 3 and 5.

Effectiveness depends on timeliness of seed application, choice of seed, pilot skill, protection from grazing, and luck in having gentle rains to stimulate seed germination before wind or heavy rains blow or wash soil and seed away. Proper timing of seed application depends on location. In some areas it is best to drop seed directly into dry ash, before any rain falls, to take advantage of the fluffy seedbed condition, while in others seed is best applied after the first snow so that it will germinate in the spring. Both conditions also reduce loss to rodents. Choice of seed determines how easily it can be applied – some grass species with long awns tend to clog in seeder buckets, and light seeds drift more than heavy ones – and how well it will grow, how long it will persist, and what impact it will have on natural regeneration. In general, legumes have not been found to be particularly effective at producing cover (there are exceptions). A skillful pilot will apply the seed evenly, rather than in strips with unseeded areas in between them, providing better ground cover once the seed germinates.

A few respondents also mentioned that straw mulch, needle cast, slope barriers such as straw wattles or contour felled logs, or ripping the soil enhanced growth of seeded grasses. Maximum cover of seeded species is not attained until summer. Many respondents reported that seeding was not particularly effective at producing protection from the first year’s storms (especially in the Southwest for fires that occur just before the monsoon season with its high intensity rains) but may provide effective cover during the second and subsequent years. Several respondents suggested that waiting to seed onto snow for spring growth would be the most effective course of action in the Southwest (Region 3), because they usually ended up having to do a second seeding anyway after the summer monsoon washed the first application away. Several respondents noted disappointing results from seeding with relatively expensive native species or Regreen (commercially available sterile wheatgrass hybrid) and would not use them again. On the other hand, cereal grains were generally reported to perform well the first growing season. Cereal grains that do not germinate in quantity the second year provide soil cover with the mulch from the dead first year growth. Both cattle and elk grazing were reported to reduce the effective cover of seeded grasses. Seeded grass cover tends to be higher on low angle slopes (less than 40 percent) than steep ones.

Implementation and Environmental Factors: Many respondents reported difficulties in contracting for seed and aircraft operators which, especially after fall fires, resulted in seed being applied too late for optimum conditions. Ground sampling, with sticky papers or by visual inspection, should be done to monitor seed application rate and evenness. Fixed wing aircraft may be less expensive per application but can be less accurate at directing seed than helicopters. The use of native seed is a major issue on many Forests. Native grass seed can be hard to acquire in large quantities or in a timely manner compared to cereal grains or pasture grasses; it is also generally more expensive. Native seed should come from a nearby source area to preserve local genetic integrity. Cereal grains will germinate and grow the second year if the ground surface is disturbed by salvage logging or grazing. Many monitoring studies have found lower cover of native plants in areas with high seeded grass cover, even where seeding increased total cover. Some-times this resulted in lower total cover after the seeded grass decreased in abundance. On the other hand, seeded grass may also inhibit growth of noxious weeds that invade sites after fire, a beneficial outcome. Rhizomatous (sod-forming) grasses make reforestation more difficult if they achieve significant cover. It is important to know the composition of prefire vegetation when proposing to seed – if the vegetation included many annuals or lots of perennial grass or sedge, there will usually be considerable cover established naturally after a fire.

Other factors: Many respondents noted that grass seeding was sometimes done primarily for "political" reasons, especially at the wildland-urban interface.

Aerial Seeding - Planning and Implementation


Aerial seeding is often the largest cost associated with burned area emergency rehabilitation projects. The complexities involved in implementing safe and efficient aerial seeding operations demonstrate the need for a logical, planned approach for accomplishing needed work. If a project is not well-planned, opportunities exist for things to go wrong, the potential for accidents and injuries increases, and the probability of not accomplishing the work increases. In the haste of trying to get work done within short timeframes, one must ensure that critical tasks and/or responsibilities are not overlooked.

Aerial seeding requires contracting assistance. It requires the purchase of often large amounts of seed and the use of specialized equipment to implement emergency prescriptions to stabilize watersheds. We must be able to secure these goods and services on short notice; and we must be able to organize to effectively and safely implement these kinds of projects.

Regardless of size, aerial seeding projects can range from simple to very complex. Each can (and will present its own set of challenges. We must be able to assess and respond to these situations.

Factors to consider when prescribing seed include:

Climatic influences
Slope and aspect
Timing of applications
Soil characteristics
Need for structural aids (mulch, site preparation, etc.)
Management direction for the area
Runoff characteristics of the area


Burned Area Emergency Stabilization and Rehabilitation (ESR) projects are EMERGENCY situations. Anything that can be done to facilitate the process prior to the need arising will most certainly be helpful. Because of the many complexities involved in implementing aerial seeding prescriptions, a project manager should not go into an incident cold. He or she will be much better off some preplanning has been done.

There are many tasks that can be completed ahead of an incident that will facilitate efficient implementation of aerial seeding prescriptions. These include but are not limited to the following:

Agency Administrator Commitment - Brief your appropriate agency administrator on the objectives of ESR. Make sure they understand its EMERGENCY nature and the URGENCY of getting the job done. Obtain their pre-incident commitment to accomplishing the work. Give ESR work PRIORITY over other work items.
Aerial Application Contracts - Assemble sample aerial application contracts from previous incidents. When embarking on a project and time is short, it is best to have some idea of how to proceed. Talk to someone who has had experience; or ff you have been involved before, use those methods that have proven effective.
Contracting and Procurement 
Work with your contracting and procurement sections to develop a list of potential aerial application contractors. Not all operators are the same and they may have differing amounts of support equipment available. It is beneficial to have this list in advance because of the short time available to solicit bids. Talk with someone who has had experience in aerial application in your area.
Develop a list of REPUTABLE seed suppliers. Seed suppliers are like any other businesses. Some are good and some are not so good. Try to find out who has provided the best level of service in your area. Find out if there have been problems with any of the suppliers in the recent past.
Seed Laws - Fully understand the laws governing the purchase and application of seed in your local area. This includes provisions for seed testing, labeling, and procedures for non-compliance. One of the worst things that can happen on a ESR project is to apply seed containing noxious weeds or other undesirable species. Every effort should be taken to ensure this does not happen.
 Warehouse Space - Know the availability of large rental warehouse space in your local area. If a large scale seeding effort is planned, a place to store seed out of the weather is needed. This is particularly true when seed is delivered in bags. Also, provisions need to be made for loading and unloading seed at all times of the day or night. Fork lifts, or other loading machinery, need to be planned for.
Develop a list of personnel experienced in aerial application. In order for implementation to proceed smoothly, access to skilled individuals on short notice must be available. These individuals are often assigned to incidents for more than 14 days.
The kinds of skills required on an aerial seeding project include the following:
Map Preparation - The importance of high quality maps on an aerial seeding project cannot be over emphasized. Maps provide the necessary link between survey team and implementation team. They are also necessary components of seed procurement and aerial application contracts. Seed is not always cheap and it must be known in advance how many acres are to be treated with a particular seed mix. It is also critical that seed be applied to the proper treatment areas.
Air Operations - All aerial seeding projects require the skills of an experienced air operations manager. This person or persons should be familiar with fixed-wing and/or helicopter operations. They should fully understand the capabilities of aircraft involved including payload, maneuverability, and navigation requirements. Proper air-to-ground and ground-to-ground communications are essential on aerial application projects. Air operations personnel need to familiar with communications equipment and procedures. Since this person will be overseeing aerial application operations, he or she must be familiar with FAA and internal agency aircraft safety rules and procedures. This person also needs to be familiar with other kinds of equipment used in aerial application of seed. This includes seed buckets or other types of seed delivery systems and their proper calibration, loading equipment such as preload chutes and bins, and seed storage and transportation.

Communications/Dispatch - Proper communications are an essential component of a successful ESR incident. An experienced communications unit leader will be an important part of any ESR implementation organization.

Administration - his person should be familiar with agency accounting procedures for ESR, be able to keep accurate records, and understand procurement procedures and authorities. 


Once assigned the responsibility of implementing an aerial seeding project, a number of factors must be considered when planning and organizing the operation, and in developing contracts. An excellent means of getting an early start is to get involved with the ESR survey team. This will provide you with an understanding of the prescriptions being considered and important characteristics of the land area to be treated.  Some of the most important items that need to be considered include the following:

Size of fire or complex of fires.
Geographic location and accessibility.
Elevation and climate.
Management areas/sensitive areas.
Landowners involved.
Number of seed mixes.

Calculating Seed Rates Based on Pure Live Seed per Square Foot

Seeding rates for grasses are generally expressed in pounds per acres. However, if a seeding prescription is based on pounds per acre instead of Pure Live Seed (PLS) per square foot, excess costs can be experienced. Generally, to achieve efficient erosion control, seeding rates should be in the range of 30 to 60 PLS per square foot.

Seeding rates can be calculated if you know the following:

The total number of seeds per pounds
The percentage of each pound that is PLS
How many acres needing treatment
The target PLS per square foot rate


Seed one acre with Standard Crested wheatgrass which has 175,000 seeds per pound and is 76% PLS to get a result of 40 PLS per square foot.

(1 acre)*(43,560 ft2/acre)*(40)=1.742,000 PLS
(175,000)*(0.76)=133,000 PLS/lb
(1,742,400)/(133,000)=13.1 lb


Seed one acre with three species at different rates to obtain a coverage of 30 PLS/ft2

Species 1 = 175,000 seeds/lb; 76% PLS; 30% of mix
Species 2 = 645,000 seeds/lb; 71% PLS; 40% of mix
Species 3 = 227,000 seeds/lb; 87% PLS; 30% of mix

(1 acre)*(43,560 ft2/acre)*(30)=1,306,800 PLS

Species 1: (1,306,800)*(0.30)=392,040 PLS
                    (175,000)*(0.76)=1333,000 PLS/lb
                    (392,040)/(133,000) = 2.95 lb

Species 2: (1,306,800)*(0.40)=522,720 PLS
                    (645,000)*(0.71)=457,950 PLS/lb
                    (522,720)/;(457,950) = 1.14 lb

Species 3: (1,306,800)*(0.30)=392,040 PLS
                    (227,000)*(0.87)=197,490 PLS/lb
                    (392,040)/(197,490) = 1.99 lb

Total Mix: 6.087 lb/acre


In order to purchase seed, we need to establish and state what is minimally acceptable to the government. Although the need for seed may be great, it is important to provide all necessary information for seed procurement to prevent problems which may occur later. The following are items which should be addressed in the solicitation:

Pure Live Seed Requirement - The minimum acceptable pure live seed (PLS) must be stated. The PLS is the purity of the seed multiplied by the germination percentage.
The term germination means the percentage of seeds capable of producing normal seedlings under ordinarily favorable conditions.
The term purity means the percentage of the specific seed, by weight, contained in a sample.
Applicable Laws - These laws pertain to selling and transporting of seed or to noxious weeds. The Federal Seed Act (7 U.S.C. Sections 1551-161 0) applies to all acquisitions of seed. Laws of the State to which seed is supplied, are also applicable.
Mixing - Mixing requirements should be described. Example: species of seed for each mix shall be thoroughly and uniformly machine mixed.
Treatment - The specifications should state whether seed treated with a fungicide is required or, if not, is it acceptable.
Packaging and Marking.
Specifications should require the seed to be packed for shipment in such a manner that will ensure acceptance by common carrier and safe delivery at destination. Containers and closures should comply with Interstate Commerce Commission regulations.
The method of packaging should be specified. For example, is the seed to be shipped in bulk or bags. If the seed is to palletized, it should be stated in the specifications.
It needs to be stated in the specifications, how shipping containers are to be marked. This should include, as a minimum, the species, weight, purity, and germination, and the date of the latest state or commercial seed laboratory test. In addition, the Federal Seed Act and State laws also require specific information to be listed. The Federal Seed Act requires a certification tag to be on each shipping container.
Testing Requirements - Any testing requirements should be listed in the specifications. We should state what kind of testing is acceptable, where testing can be done, and if a certificate of the testing is to be furnished.
Delivery Locations - Delivery locations must be listed in the solicitations. The location of storage facilities should be listed, as well as hours and days of operation. We may wish to be notified in advance of when shipments will be delivered.  If a large amount of seed is being acquired, we may need to consider obtaining facilities to store the seed until it is applied. Seed needs to be stored in dry, rodent-free facilities. It may be necessary to rent storage facilities. In addition, arrangements may need to be made to handle the seed. Bidders need to be told if they are required to unload the seed, and, if so, whether to place it on the loading dock or within the storage facility. Bidders need to know a fork lift and operator will be provided.
Delivery Time - The required time of delivery must be stated in the solicitation. This is normally stated as the number of calendar days after award of contract. If the seed is urgently needed and we are not sure how quick a supplier may be able to provide the seed, it may be appropriate to call a few suppliers and ask them how quickly the seed could reasonably be supplied.
Inspection and Acceptance.
The government has the right to inspect and test all seed called for by the contract. We should perform all testing we believe necessary to assure ourselves that we are receiving what we requested. Following testing, we can decide whether to accept the seed. Once formal acceptance of the seed is made, we have limited rights in going back to the contractor and rejecting the seed. The only time we can do this following final acceptance is when we determine the seed does not meet specifications based on latent defect, fraud, or gross mistakes amounting to fraud. If we accept seed without adequate inspection and subsequently determine the seed does not meet our specifications, we may have forfeited our right to have the defect corrected or the seed replaced.
There a number of options available to have seed tested:
As a minimum, we should check to see if the appropriate tags are the containers, and check to see if data on the tags indicates the seeds meet specifications.
We can take samples of the seed and send them to a certified laboratory to have the purity and germination verified. This can take several weeks to months depending on species. Noxious weed tests can be done in a much shorter time (24 hrs.) if the laboratory agrees to do so.
The contractor should provide copies of certified tests done on the seed prior to mixing or shipping. These certificates should be checked for compliance with specifications.
Individual units may have specific policies regarding testing prior to spreading seed.
One option of dealing with seed testing prior to acceptance is to do minimal testing upon receipt of seed (i.e. noxious weeds) and to spread the seed prior to final acceptance. This allows us to make an appropriate deduction if, following testing, we find that other purity factors or germination requirements are not met.
Payment - The contract must state how payment will be made. Normally, this is merely stating that payment will be made at the price stated in the contract schedule of items following receipt and acceptance of the seed. The contractor should be notified if we plan to delay final payment pending receipt of germination testing.


Aerial application of seed may be accomplished by using either of two basic types of contracts:  Full Service or Call When Needed (CWN) or Job Contract.

Full Service or CWN Contracts - Under full service or CWN, the contractor is required to make specific aircraft available for exclusive use by the Government, normally for the transport of cargo or personnel. Payment is made by unit of time, generally hourly with a daily guarantee. The aircraft and pilot must be carded and the aircraft must be inspected by a FS/OAS mechanic. The benefit of this type of contract is that the Government exercises substantial control over the project. Specifications list all minimal requirements for aircraft and award based on a cost basis. This type of contract might be used where we are unsure of where treatment is needed on the ground. Because of the greater amount of control exercised by the Government, we also assume a larger portion of the liability and risk. The contractor doesn't have the same incentives to maintain an efficient operation which raises our cost risk. Risk of project failure is ours, along with liability assumed due to our directing the work.
Job Contract.
Specifications in a job contract are written to state the work to be accomplished and the level of acceptability. As a minimum, we need to give potential contractors enough information to prepare a bid and perform the work under the contract. The following are factors which should be listed in the solicitation:
Locations and accessibility - Locations of project areas should be stated in terms of accessibility and written directions. They should be shown on maps. Information on elevation and terrain should also be provided as well as potential helispots and airstrips.
Certification and licensing requirements.
Government furnished property.
Seed (if  we provide), how it is packaged, size of container.
Location of government furnished seed, how ft can be removed from storage, point contractor assumes control of seed.
Topographic maps, orthophotos, airphotos to be furnished to contractor.
Contractor furnished property and services.
Seed (if they provide).
Loading, transporting, and off-loading of seed.
Selection of heliports/airstrips.
Suitable aircraft with experienced pilots.
Qualified ground supervisors and equipment.
Dust abatement/warning signs/garbage cleanup.
It should be stated that equipment moving and ferry time is incidental to cost of seeding.
No government employees to ride in contractor furnished aircraft.

Avionics requirements should be listed. If the contractor must furnish any radios compatible with government radios, it must also be stated.

Seed mixes and application rates - Data tables should be included in the attachments that show seed mixes, application rates, and total pound by application block.

Seed application system.

spreading system.

bucket type and size.

adjustable calibration.

calibration test requirements.

Seed application.

List any criteria that will be used to determine when application operations will begin or cease.

wind velocity


surface runoff

air turbulence


equipment failure/avionics

List any maximum load limits.

Altitude/airspeed requirements to meet calibration.

Periodic checking of calibration.

Application to cease during turns.

 No dumping of seed.

Measurement and payment - It should be stated how payment will be made. Normally payment will be based on pounds of seed satisfactorily applied within unit boundaries. Pound spread should be as determined in the inspection provisions. No payment should be made for seed not spread as required in the specifications.

Inspection and maintenance.

Avionics equipment should be inspected when the contractor arrives to ensure it is functional and satisfactory for intended

The rate of spread may be monitored in the following ways: 

By using seed collection devices.

By calculating weight to acres.

Observation of flight pattern and spacing as well as on the ground results.

Contract Time - A realistic amount of contract time should be allowed in the contract. In determining the contract time, consider the number of hours available during the normal work day when suitable weather will permit application to occur. This may only be 3-5 hours per day.

Even though a job contract may be used on an aerial seeding project, an approved aviation safety plan must be in place before the contract can be awarded. The contractor must comply with all Office of Safety and Health Administration (OSHA) safety regulations.


A detailed operations plan is a necessity for all aerial seeding projects. On such projects, a large amount of work needs to be accomplished in short time periods people are working in situations that may be considered dangerous, and people are asked to perform tasks that may be unfamiliar to them. Some people assigned to the incident may be from other administrative units and may not be familiar with the local geographic area or local administrative procedures.

Some of the topics that should be covered in an incident procedures plan include the following:

Introduction - This section should contain a clear statement of project objectives, a description of the work to be done, desired timeframes, reasons the work is important, and other resource considerations.
Safety Plan. - 
The health and safety of all personnel MUST be of primary importance. Project managers MUST accept responsibility for preventing accidents and ensuring each employee works in a safe and healthy environment.
Project managers MUST institute a policy to promote safe practices and to eliminate accidents and unsafe conditions. Trade-offs in safety procedures cannot be made in the interest of accomplishing work. 
A safety plan should include the following:
Project policies.
Goals and objectives.
Clear statement of responsibility.
Safety procedures.
Accident prevention.
Job hazard analysis.
Orientation and training.
Personal protective equipment.
Hazard inspections.
Air operations safety.
Vehicle safety.
Visitor safety.
Traffic control road closures.
First aid requirements.
Safety meetings.
Accident reporting and emergencies.
Forms and Guidelines.
Emergency medical plan.
Accident investigation.
Search and rescue.
Organization - Aerial seeding projects require experienced personnel with special skills. However, in many cases, these kinds of skills are not readily available and people are asked to perform tasks that may be unfamiliar to them. A clear description of the project organization and the kinds of jobs to be done is needed.
Organization chart - Include a chart showing the incident organization along with clearly defined lines of responsibility.  Each person assigned to the incident should be shown as a box on the chart.
Job descriptions - For each position on the chart, a written job description is needed. Job descriptions should include a general description of responsibilities, a detailed description of duties, and a listing of knowledge, skills, and abilities required by the position. Job descriptions are important because:
Give a clear picture of tasks to be done to both experienced and inexperienced personnel.
Provide basis for performance appraisals and evaluations.
Provide basis for developing future training programs.
The successful and safe completion of ESR incidents depends on good communications between all personnel involved. Adequate ground-to-ground and air-to-ground communications are essential. Someone that fully understands principles of radio communications and equipment involved needs to be assigned-to the project.
The incident communications plan should include the following:
Dispatching procedures.
Downed aircraft reporting.
Radio frequencies.
Agencies frequencies.
Tactical frequencies.
Pre-project operations.
Secure landowner consent and other required clearances.
Designation and ground marking of seed block boundaries.
Designation of sensitive or no-treat areas.
Designation and approval of helispots and airstrips.
Hazard map.
Provide necessary training for incident personnel.
Incident orientation.
Aircraft safety.
Contract administration.
Calibration and characterization of aerial application equipment.
Secure needed supplies and materials.
Locate and map locations of structural measures.
During Operations.
Description of typical operations day.
Describe who is responsible for certain tasks at particular times during the day.
Personnel locations.
Communications checks.
GO/NO GO decision points.
Aircraft equipment checks.
Take off/landing records.
Load logs.
Accomplishment reporting.
Next day program of work.
Description of decision standards.
air turbulence
Improper seed dispersal
monitoring procedures
correction of problems
retreatment decisions
Aircraft equipment problems
mechanical problems
seed delivery problems
Required reports and records distribution.
Material transfer records
Daily accomplishment
Daily aircraft records
Contract daily diaries
Daily radio logs
Daily shift plans
Operations check list
Monitoring results
Tailgate safety meeting documentation
Post operations - Carry out demobilization plan as described below.- 
Demobilization plan.
Debrief project personnel.
Performance appraisals.
Permanent project records file.
Cost accounting.
Operations plan.
Return equipment.
Project critique.
Letters of appreciation to project staff and other cooperators.
Calibration formulas.
List of seed mixes and desired number of seeds per square foot.


Helicopters versus Fixed Wing.

Two kinds of aircraft can be used to apply seed: helicopters and fixed wing. The kind of aircraft best suited for a given project is dependent on a number of factors including:
Project objectives
Size of treatment blocks
Location of landing/staging areas
When determining the kind of aircraft to be used on a project, keep in mind the following:
Cost, availability
Qualifications of applicator
Prior performance and experience
Types of aircraft being offered
Comfort level of project manager
GPS Navigation Systems - There are several suitable navigation systems available. You need to determine which system best meets your needs. On some projects, eyeball systems may provide good results at low cost.
Monitoring Application.
Observer aircraft.
GPS navigation.
Ground observers with radios.
Ground observers with seed collection devices.
Landing monitors observing acres flown vs. seed consumed.
Combination of above.
Support Equipment.
Fuel trucks.