Final Staff Report and 

Recommendations on Agricultural Burning 

Chapter 4 

Technological Feasibility of 

Alternatives to Burning 
Final Staff Report and 

Recommendations on Agricultural Burning 

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Chapter 4: TECHNOLOGICAL FEASIBILITY OF

ALTERNATIVES TO BURNING

District staff has conducted detailed research and identified several potentially 

feasible alternatives to open burning of agricultural materials. Some of the 

alternatives were previously identified during the 2005 and 2007 burn prohibition 

schedules. Potential alternatives for agricultural wood and agricultural non-wood 

materials were identified for each of the following groups: 1) vegetative and 

related material and 2) animal-related material. 

The more common methods of disposing of agricultural material that cannot be 

open burned include the following: 

• Some agricultural materials, like orchard removals, are primarily 

transported to biomass power plants for use as fuel. 

• Chip or grind the material and transport it off-site for disposal or other 

renewable uses. 

• Prunings and some field crop materials may be shredded in place, 

chipped onsite, or tilled into the soil. 

• Some materials, such as rice straw, may be baled and sold for various 

commercial purposes, although the market for such product is much less 

than available supplies. 

The potential alternatives to open burning of agricultural wood and agricultural 

non-wood materials are described below. 

4.1 VEGETATIVE AND RELATED MATERIAL 

Most alternatives to open burning agricultural wood materials and pruning 

materials require that the agricultural materials go through a chipping, grinding or 

shredding process. These processes are typically used to change the 

agricultural wood materials into a more manageable and useable size. Some of 

the benefits of chipping, grinding and shredding include faster decomposition of 

the materials, easier incorporation into the soil, easier to process and transport, 

and better combustion when used as fuel at biomass power plants. 

Agricultural wood and pruning material that are to be chipped need to be as free 

of debris as possible to prevent damage to the chipping equipment and to 

increase its acceptability by potential end users such as biomass power plants 
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and other processors. Orchard removal material is usually removed from the 

farm after the chipping process, as growers want a relatively clean field for 

planting a new crop. For pruning, growers may recycle the materials onsite or 

remove the material from the farm. 

4.1.1 Biomass Power Plants 

Biomass power plants in the SJVAB will generally accept agricultural, forestry, 

construction, and urban residues. The power plants burn the material in 

combustors to produce steam. The steam is then used to spin turbines to 

generate electricity. 

Biomass power plants do not universally accept all agricultural material due to 

concerns that some materials may harm power plant machinery. Several issues 

have been noted concerning the types of material, such as citrus chips, that can 

be burned by the biomass power plants and the amount of agricultural materials 

that is accepted at the biomass power plants at any given time. Biomass power 

plant operators have indicated that these issues have been overcome over the 

past few years as the facilities involved have adapted in processing the ag 

materials to better suit the situations encountered. 

Using the orchard removal materials for fuel at the biomass power plant is 

currently the most viable and cost effective alternative to open burning for 

growers due to available tax credits for biomass facilities and required 

agricultural offsets for some biomass power plants. However, reliance on 

biomass fuel as a primary alternative to burning is somewhat uncertain since 

there are no long-term federal or state funding commitments for the biomass 

facilities in the SJVAB. It is also relatively more affordable for the biomass power 

plants to accept urban waste than agricultural materials. Pruning materials are 

sometimes accepted by biomass power plants. The residents of a typical 

community are being charged more money to divert urban waste out of a landfill. 

Therefore, the urban waste is subsidized by the community in their waste 

payments and this provides the urban fuel to be processed at biomass plants at a 

more competitive price. 

4.1.2 Land Application/Soil Incorporation 

Applying agricultural materials to the soil is a common method of disposal of the 

materials. The pruning material from many tree crops and vineyards is usually 

gathered into windrows and shredded in place using grinders suitable for brush. 

The shredded material can either be left on the ground or be incorporated into 

the soil when the field is tilled. Over time, the material decomposes into the soil 

which adds valuable organic material to the soil and can lead to better water 

infiltration and soil quality. This practice is evolving as more growers and 
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equipment manufacturers innovate and collaborate to make the process work for 

everyone. 

Current practice does not work well for all crops, especially for pome (apple, 

pears, and quince) fruits with concerns over the spread of diseases and for nut 

crops which harvest the nuts from the ground. With the exception of the potential 

spread of diseases from pome fruits, other operators can usually minimize or 

prevent this problem for other crops by taking steps to better ensure that chipped 

pruning material has decomposed by the time that crops are harvested or that 

chipped pruning material is not placed in the area where the crop is to be 

harvested. The pruning material can be chipped into smaller pieces using 

upgraded technologies that can shred the material into finer quality. The cost of 

this equipment will be assessed later in this report to determine if it would be 

economically feasible. 

4.1.3 Anaerobic Digestion 

Anaerobic digestion is a biological process that decomposes organic matter with 

minimal or no oxygen level, which results in a liquid/solid stream (digestate) and 

biogas that contains mostly methane and carbon dioxide. This biological process 

can either be found or managed through some of the following: marshes, 

sediments, wetlands, the digestive tracts of ruminants and some insects, landfills, 

many wastewater treatment facilities, and animal feeding operations and dairies. 

The anaerobic digestion technology that is managed at a farm or facility could 

include several steps in the process, such as feedstock handling/storage, 

preprocessing, digester, collection and storage of the biogas, dewatering of the 

digestate, and handling/storage of the dewatered digestate. 

There are currently no commercial-scale solid waste digesters in operation in the 

United States even though anaerobic digesters have long been used to treat 

agricultural and municipal wastewater. Although, District staff has found that the 

anaerobic digestion technology will be installed in Emmetsburg, Iowa, in 2011, as 

part of a commercial scale cellulosic ethanol plant. The digestate would be used 

as a source to power the plant. 

District staff is not aware of any facilities in the SJVAB that can process 

agricultural materials through anaerobic digesters on a commercial scale. In 

addition, it is not believed to be practical to require that growers install an 

anaerobic digester for the purpose of disposing the agricultural material. The 

agricultural materials that are subject to Rule 4103 are typically pruned or 

removed once a year or every few years for orchard removals. Based on these 

considerations, District staff will not conduct further analysis on anaerobic 

digesters as a viable technology in the SJVAB. 
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4.1.4 Composting 

Composting is the process by which organic material is broken down aerobically 

to form a biologically stable organic substance suitable as a soil enhancer and 

plant fertilizer. 

Agricultural material is one of the sources of organic material for composting 

operations. Other sources could include, but are not limited to, urban waste, 

biosolids, and manure. The District distinguishes the blend of organic material 

into two categories, composting and co-composting. Along with vegetative 

material, co-composting includes biosolids, manure, and/or poultry litter. The 

vegetative materials are a good source of nitrogen, whereas, chipped wood 

provides carbon to the mixture. As a result, compost and co-compost facilities 

sometimes accept agricultural materials either as feedstock or as amendment for 

the operation. Some compost and co-compost facilities also accept and store 

the material for other use such as fuel for biomass power plants or animal feed. 

Based on District’s data, there are currently 19 composting and co-composting 

facilities in the SJVAB that might be able to accept and process the agricultural 

material. 

Sources usually pay a tipping fee to compost operators to dispose of the material 

at the composting site. With competing materials from subsidized urban waste, 

disposal costs for agricultural materials could be higher and the accepted amount 

of agricultural materials could vary. This fee would be additional to other 

operational costs, such as chipping and transporting the material to the compost 

facility. These operational costs for the grower would be similar to the cost of 

chipping and transporting the material to the biomass power plants, which does 

not charge a fee for disposal. Based on discussion with the chipping operators, 

most of the agricultural materials that are chipped are transported to biomass 

power plants for use as fuel. Therefore, District staff plans to conduct the 

economic feasibility analysis on transporting the material to biomass power 

plants as a more cost effective alternative. 

4.1.5 Landfill 

Growers and chipping companies can take agricultural materials to local landfills 

for disposal. Not all landfills will accept these materials, particularly landfills 

designated for hazardous waste. Municipal solid waste landfills are allowed to 

receive putrescible waste, such as yard waste or any methane producing 

material. Agricultural materials accepted at these landfills may be disposed at 

the site but are primarily being used as alternative daily cover (ADC) to reduce 

odor and for vector control. State Assembly Bill AB 939 was passed in 1989 and 

mandated local jurisdictions to meet solid waste diversion goals of 25 percent by 

1995 and 50 percent by 2000. Local agencies within California are required to 
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comply with the mandated landfill diversion requirement every year. 

There are four landfill facilities within the District that are currently accepting 

organic material, which could include materials from agricultural crops and 

orchard removals. Similar to compost facilities, landfills also charge tipping fees 

for the disposal. Due to the state mandated landfill diversion requirement and 

the small number of landfills that are allowed to accept organic material, it is not 

feasible to promote agricultural material going to the landfills. District staff has 

considered the information above and plans to conduct the economic feasibility 

analysis on transporting the material to biomass power plants as a more cost 

effective alternative. 

4.1.6 Cellulosic Ethanol Production 

Cellulosic ethanol, a key next-generation biofuel, can be made from switch grass, 

corn stover, forest waste, fast-growing trees, wood chips and other plant 

material. 

Advanced biofuels are those that do not rely on the corn kernel starch. In 

contrast, the most common type of ethanol in the United States is corn ethanol 

which is produced from corn with only the grain being used. Corn ethanol is 

primarily used in the United States as an alternative to gasoline and petroleum 

(first-generation biofuel). 

The production of cellulosic ethanol is still predominately in the demonstration 

plant phase of development. At this time, District staff is not aware of any 

commercial plant within the SJVAB that currently uses agricultural materials for 

the production of cellulosic ethanol. 

4.1.7 Gasification for Liquid Fuels 

There are emerging technologies that can convert agricultural materials, sewer 

sludge, wood, trash, and plastics into diesel or biofuel. In traditional gasification, 

oxygen is used, but the new technique uses hydrogen and steam at nearly 1,500 

degrees F to break apart the feedstock into a gas made up of its molecular 

components. After gasification, the resulting gas then goes through additional 

steps that produce water, wax, and diesel fuel. Up to 85% of the feed material 

becomes usable liquid fuel at the end of the process. 

Agricultural wood materials can be used as a solid fuel by being burned in a 

combustion device or it can undergo processing to convert it into a gas or liquid 

fuel. Operators could choose to purchase a system given adequate space, but 

many of these vendors are located outside of California. For most of these 

situations, the agricultural wood materials are usually chipped on the farm site 
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and then transported to the processing facility. District staff is not aware of these 

types of facilities currently in operation in the SJVAB, which would indicate that 

these technologies are not current alternatives to burning. 

4.1.8 Pyrolysis 

A new biofuel derived from wood chips through a pyrolysis process has been 

developed. The process involves heating wood chips and small pellets in the 

absence of oxygen and high temperature (pyrolysis). About a third of the dry 

wood becomes charcoal and the rest becomes a gas. The gas then undergoes a 

chemical process where it is converted into liquid bio-oil. According to 

researchers, the new method offers environmental benefits and could reduce 

industrial costs of alternative fuel for conventional diesel engines. The technique 

is still in the early stage; therefore, use of wood chips for this process would not 

be a viable alternative source in the SJVAB at this time. 

4.1.9 Mulch 

Soil Stabilization / Dust Control 

A project in Northern California gauged the use of wood chips as an alternative 

source for soil erosion and stability to roads and parking areas. The Road 

Stabilization and Improvement Demonstration Project demonstrated that the use 

of wood chippings not only provides stabilization and erosion control on light 

duty, low-use roads, parking, and access areas, but is also cost-effective when 

compared to the use of other road materials. 

The project found that using wood chips for road use was a feasible alternative to 

expensive materials such as rock or shale. Other benefits resulting from the 

project include added value to the chipped materials, improved site and off-site 

water quality, improved stability, usability, and mud free road and area 

conditions. The project addresses the successful use of wood chippings for soil 

stabilization or dust control as potential alternatives. District staff is not aware of 

a feasible market in the SJVAB that could accept and process all of the 

agricultural material for use as dust control but this alternative would be 

considered as a similar alternative to soil incorporation and a possible option, 

given that the materials serve as beneficial use. Typically, operators apply the 

chipped material onto surfaces for nutrient value and may apply the extra 

material on road surfaces. In other cases, not all roads are in need of chipped 

materials. 

Hydraulic Mulch 

Agricultural material can be shredded into wood fiber and used as hydraulic 

mulch by Caltrans or others. Hydraulic mulch is a mixture of shredded wood 

fiber or a hydraulic matrix and a stabilizing emulsion or tackifier. The mixture is 
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typically applied to disturbed areas requiring temporary protection until 

permanent vegetation is established or disturbed areas that must be re-disturbed 

following an extended period of inactivity (Caltrans Storm Water Quality 

Handbooks, Section 3, Hydraulic Mulch SS-3). Caltrans uses hydraulic mulch as 

one of the alternatives to temporarily protect exposed soil from erosion by rain or 

wind. However, the wood fiber hydraulic mulches are generally short-lived, 

lasting only a part of a growing season, which operators may have to take into 

account for long-term projects. In addition, for the wood fiber hydraulic mulches 

to be effective, the material requires a drying time of 24-hours (Standard 

Specifications Sections 20-2.08). 

Wood chips to be used as hydraulic mulch are required to be cleaned and free of 

salt and deleterious materials such as clods, coarse objects, sticks, rocks, and 

weeds. Such requirements may minimize efficiency during processing of the 

agricultural materials, and increase costs from separating the material or 

diverting different parts of the material to various locations for alternative use. 

Use of hydraulic fiber mulch has increased over the years as it has proven to be 

a cleaner alternative to hay or straw mulches, however, staff is not aware of 

agricultural material being used for the hydraulic mulch process on a market 

scale. Therefore, staff will not pursue this option as a feasible alternative for 

open burning of agricultural material. 

Wood Mulch 

Agricultural materials could also be recycled as wood mulch. Wood mulching 

can be used in landscape projects or for erosion control and may be a mixture of 

shredded wood mulch, bark, and compost. The material is primarily used to 

reduce erosion by protecting bare soil from rainfall impact, increasing infiltration, 

and reducing runoff. Caltrans found that wood mulching can be used as 

temporary soil stabilization for disturbed areas awaiting revegetation and 

permanent cover or as a temporary, non-vegetative ground cover on slopes 

(Caltrans Storm Water Quality Handbooks – Section 3, Wood Mulching SS-8). 

As part of wood mulching, the greeneries from the agricultural materials may also 

be used for similar purposes and composted as necessary to kill weed seeds. 

However, there are limitations to using wood mulch, such as introduction to 

unwanted species, possible sheet erosion because the material cannot withstand 

concentrated flows, and the green materials may bring in unwanted weeds and 

plant materials. In addition to these considerations, staff is not aware of most 

agricultural material being used for this process on a market scale. Therefore, 

staff will not pursue this option as a feasible alternative to open burning of 

agricultural material. 
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4.1.10 Hand Crews for Removal of Materials 

Some operators have considered using hand crews to remove materials, such as 

weeds, as a potential alternative for open burning. The labor-intensive removal 

of individual weeds is often characterized with unreasonable costs and safety 

issues. Additionally, hand removal of weeds is technically unfeasible due to the 

magnitude of weed abatement. Technological development is needed to reduce 

the burning of weed abatement material. 

4.1.11 Overseas Shipment of Raisin Trays 

In the past, some growers have shipped reusable materials, such as raisin trays, 

overseas to be recycled. However, the alternative is no longer available for 

these materials. 

4.1.12 Water Decomposition for Rice Stubble (Straw)

In recent years, water decomposition has become more prevalent than burning 

rice fields stemming with the passing of the Connelly-Areias-Chandler Rice Straw 

Burning Reduction Act of 1991. The Act mandated the reduction of burned rice 

acres over a ten year period besides that which is done for disease control. 

Currently, rice farmers are restricted to burn no more than 25% of planted acres, 

or up to 125,000 acres basinwide, and have moved more to flooding rice fields to 

improve the rate of decomposition. 

Rice farmers flail mow the rice stubble into about 4-inch sections and stubble 

disk it, to ensure it has contacted with the soil four to five inches deep. It is then 

flooded as soon as possible to keep the clods covered. Flooding the fields 

during the winter helps with blast and speeds decomposition, as well as providing 

some fertilizer benefits. 

Water availability and costs for winter water are a concern but can be offset by 

other practices. Some disadvantages of water decomposition arise with certain 

weather conditions but extra precaution is taken, such as managing the water 

flow and battening down the hatches, to prevent damage to the rice patties. 

Water decomposition is a common alternative to burning and is required in areas 

that limit the amount of acreage that can be burned. 

4.1.13 Baling Rice Stubble (Straw) 

As discussed above, alternatives to burning rice fields have been sought, 

especially with the passing of the Connelly-Areias-Chandler Rice Straw Burning 

Reduction Act of 1991. Baling rice straw was a highly anticipated option when the 

Act was passed but has declined in viability. It is estimated that only about 3-5% 
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of farmers use rice straw off-field. Baling rice straw is utilized even less due to a 

diminished market need and cost of production. Soil incorporation and flooding 

rice fields are more feasible and viable alternatives while potential uses are still 

being explored.

4.2 ANIMAL-RELATED MATERIAL 

4.2.1 Burial 

Burial seems to be most suitable for small amounts of material. Burial requires 

care in site selection because as carcasses decompose, they release materials 

that can pollute ground water, particularly if large volumes are buried. 

Advantages of burial are the low cost (if the operator owns the necessary 

equipment) and biosecurity (no trucks coming to the farm to pick up carcasses). 

4.2.2 Incineration 

Field incineration is only appropriate for deceased animals in those instances 

where the spread of disease is a concern. Decisions on how to dispose of 

diseased animals are deferred to local agricultural commissioners. 

4.2.3 Rendering 

Rendering provides a much needed service to the animal industries in the 

SJVAB and is subject to certain government food safety and environmental 

regulations. There are six rendering plants in the SJVAB. Five of the plants are 

independent operations and collect animals from other sites. The sixth plant is 

an integrated plant and operates in conjunction with its affiliated animal slaughter 

and meat processing plants. 

In most rendering systems, raw materials are ground to a uniform size and 

placed in continuous cookers or in batch cookers, which evaporate moisture and 

free fat from protein and bone. A series of conveyers, presses, and a centrifuge 

continue the process of separating fat from solids. The finished fat (e.g., tallow, 

lard, yellow grease) goes into separate tanks, and the solid protein (e.g., meat 

and bone meal (MBM) and poultry meal) is pressed into cake for processing into 

feed. Other rendering systems are used, including those that recover protein 

solids from slaughterhouse blood or that process used restaurant grease. 

The five independent rendering plants provide pick up and delivery for their 

customers. The plants do not allow public drive-up delivery in order to better 

control traffic at the plant and the quality of the animals processed. The pick up 

and delivery service is not available to any operator that has animals available for 
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several reasons. A key reason is the traveling expense which may make it 

impractical to pick up small numbers of carcasses. 

Rendering companies have certain regulatory and operational restrictions 

regarding the condition of the carcasses they process. In addition to complying 

with regulations governing diseased animals, rendering companies will generally 

not accept carcasses that do not remain intact when handled. Depending upon 

the end product of the rendering process, there may be other restrictions on 

carcass quality and condition. Although this alternative is available, District staff 

does not consider rendering to be a viable or feasible alternative. District staff 

considers burial and incineration (for deceased animals with diseases) to be 

viable alternatives, which are current practices for the industry. 

4.2.4 Sterilization 

For bee hives of diseased colonies that must be destroyed, disease experts 

recommend that the frames and combs be burned in a pit and the ashes 

covered. The heavy woodenware (supers, tops and bottoms, etc.) may be 

sterilized by scraping them clean (the scrapings should be burned) and scorching 

the inside surfaces. The scorching can be done with a propane torch with 

particular attention being paid to cracks and corners. If large quantities of supers 

are to be scorched they may be stacked and painted inside with kerosene and lit. 

To sterilize large quantities of equipment, operators could set up a barrel with a 

boiling lye solution. The woodenware should be immersed in the solution and 

boiled until clean. Frames may also be sterilized in this manner.