Agribusiness, Livestock Production/Industries,

Richard, Tom L.

English

Research Papers in Economics

Agricultural Outlook Forum 2003  Presented: Friday, February 21, 2003 
 
 
THINKING OUTSIDE THE BOX: BUILDING MATERIALS AND OTHER PRODUCTS FROM 
ANIMAL PROCESSED FIBER 
 
 
Tom L. Richard 
Assistant Professor 
Iowa State University 
 
 
Why is it time to think outside the box about manure?  It is no secret that manure is on the short list of 
environmental and social concerns about livestock production.  Several decades of increasing 
specialization in agriculture have concentrated manure resources on farms, in counties, and sometimes 
whole regions where manure nutrient supplies exceed crop demand (Kellogg et al. 2000).  Because of 
the low nutrient density of manure relative to synthetic fertilizers, the transportation costs of moving it 
to areas where there is crop demand are often prohibitive (Fleming et al. 1998).  Without viable local 
alternatives, many livestock producers overapply manure (Schmidt et al. 1996, Novak et al. 1998), 
leading to nitrate leaching, phosphorus accumulation, and other water quality concerns.  Large 
concentrations of manure create other problems, such as odor (Zahn et al. 1997), which communities are 
no longer willing to tolerate.  However, the same scale and concentration that raise environmental 
concerns also create an opportunity to collect and process manure as a feedstock for value-added 
manufacturing. With this concentration, it is now possible to envision a livestock production system 
from which manure becomes a feedstock for new manufacturing processes. 
 
Manure has a number of valuable properties that can be exploited in developing new products.  All 
manures contain protein fractions that include both undigested feed proteins and proteins synthesized by 
microorganisms in the gastro-intestinal tract.  Manures also contain fiber fractions, which include 
cellulose, hemicellulose, and lignin.  These fractions, along with minerals and nutrients, represent a 
biologically processed feedstock suitable for a wide variety of purposes (Galloway, 1998).  The key to 
transforming manure, currently often viewed as a low-grade waste, into value-added products is the 
development of refining operations to convert these components into appropriate manufacturing 
feedstocks. 
 
Many of the new products that can be made from manure have traditional counterparts.  Manure has 
been used for nutrients, energy, and fiber for millennia.  While the nutrient uses, particularly as 
fertilizers for crop production, are most widely recognized, manure has also long been burned as a fuel, 
in Africa, Asia, Europe, and by Native Americans here in the U.S.  And although the idea of using 
manure in building materials may seem novel today, manure has traditionally been used throughout the 
world as a fiber source, binding agent, and surface coating in adobe and other masonry construction. 
 
Although today’s presentation focuses on the fiber and building material opportunities, it is worth noting 
some of the new or rediscovered approaches to nutrients and energy production, two of which have 
already been discussed by the previous speakers.  
 
Nutrients 
The nutrient value of manure is well established, so it is not surprising that this component has attracted 
considerable attention in recent years.  The transformation of manure into composts and pelletized forms provides a more nutrient dense, easily transportable fertilizer and soil amendment.   Compost is already 
being marketed this way by a number of facilities, and the value of this product as a fertilizer and soil 
amendment for horticulture is well established.   
 
Some types of processing may further enhance compost value, beyond the nutrients and organic matter 
usually considered.  Specially processed composts are now also being used as pesticide substitutes, 
providing plant pathogen suppression equal or better than chemical pesticides for several common soil 
borne diseases (Hoitink and Fahy 1986, Hoitink and Grebus 1994), while compost extracts are being 
used for foliar fungal disease control (Weltzhien 1992, Scheuerell and Mahaffee 2002).  Additional 
agronomic benefits, including erosion control, enhanced water holding capacity, and other soil quality 
benefits are widely recognized but only partially quantified, particularly from the economic perspective 
needed to document value and increase the price of manure products.  The value of environmental 
benefits of improved water quality (Hatfield and Stewart 1996) and carbon sequestration (Drinkwater et 
al. 1998) from better manure management strategies are also not adequately documented.  
Quantification of the auxiliary agronomic benefits will be important for efficient market pricing, while 
quantification of the external environmental benefits is essential in the consideration of public subsidies 
for these practices. 
 
While recycling manure nutrients via crop production makes a great deal of sense, an even more 
efficient strategy can be to process the manure directly into animal feed.  The nutrient content of manure 
has been shown to be 3 to 10 times more valuable as animal feed than as plant nutrients (Smith and 
Wheeler, 1979).   Part of this increased value is due to the more direct and efficient transfer of nutrients 
to human foods, while part is in consideration of the energy value as well as nutrient needs in animal 
diets.  While the ability of ruminants to utilize non-protein nitrogen gives them an advantage over other 
livestock (Smith and Wheeler, 1979; Zinn et al., 1996), refeeding has also been successful with poultry 
and swine (Day and Sweeten, 1980; McCaskey, 1995).  The principal concern with refeeding has 
historically been animal health concerns, but the use of drying, ensiling, heat and chemical treatment 
have all been shown effective at eliminating disease transmission (McCaskey and Anthony, 1979).  
However, the costs of processing combined with lower nutrient values from some processing approaches 
(such as drying and heat treatment) have limited the application of this strategy primarily to the 
refeeding of poultry manure and litter to poultry and ruminants (Hauck, 1995).   
 
A somewhat less direct means of converting manure into high protein human foods is through the use of 
aquaculture and fish ponds.  Manure treatment in ponds has been an established practice for centuries in 
parts of Asia, and is also currently found in Europe and North America (Edwards, 1980; Polprasert, 
1989).  Fish have a high feed efficiency ratio and with proper design the biological treatment processes 
in ponds can effectively address most odor and water quality issues, although pathogen survival and 
transmission can still be a concern with untreated manure (Polprasert, 1989).  
 
Energy 
Another important product which can be derived from livestock manure using currently available 
technology is energy.  Anaerobic digestion converts much of the energy in manure to methane gas, 
which can be burned for space and process heating and/or converted into electricity with an engine 
generator or microturbine (Hashimoto and Chen 1981, Badger et al. 1995).  In addition to the 
recoverable energy produced, anaerobic digestion also reduces the odor content of the manure.  While 
anaerobic digestion has been demonstrated as effective with a wide variety of manures throughout the 
world, the relatively high capital costs and management skills required have limited its application in the 
United States (Garrison and Richard 2002).  It is important to note that anaerobic digestion does not 
obviate the need to deal with the excess nutrients challenging many livestock producers.  As an enclosed system, ammonia volatilization is reduces, so the nitrogen content is higher than with many other 
manure management systems.  And because anaerobic digestion converts manure solids to water and 
gas, the moisture content of the manure actually increases during digestion.  On farms where land 
application of digester effluent is constrained by limits on land availability, liquid-solid separation 
followed by further treatment of both the liquid and solid streams would probably be required. 
 
Fiber 
 
Another potentially valuable component of some manure streams is the fiber.  Undigested fiber is a 
significant part of ruminant manure, and fiber is a major component of biomass bedding materials like 
sawdust, straw, etc. The building materials industry has an urgent demand for alternative fiber sources 
(Bowyer, 1995, Clancy-Hepburn, 1998), and the use of manure fiber would provide a welcome 
alternative.  One of the principal limitations on biocomposite manufacturing is the relatively high cost of 
the conventional adhesives used as binders and fibers in the composite matrix.  Biorenewable proteins 
can provide excellent adhesive properties in building materials, as has recently been demonstrated with 
soy protein.  Manure protein and fiber are already blended together, which may allow reductions in the 
need for conventional adhesives in biocomposite materials.  One key to transforming manure is the 
development of refining operations to separate the fiber and liquid components into appropriate 
manufacturing feedstocks.  Composting may play a role in that refining process, evaporating water using 
the heat generated by non-fibrous cellular material.   
 
Fiber is the largest single constituent of livestock manures (excluding water) (see table 1), with over 20 
million tons generated in the US.  These estimates do not include the fibrous bedding and litter used in 
many dairy and poultry systems, providing an even greater potential for fiber recovery and use.  The 
fibers in feed and bedding are ground, homogenized, softened and coated with bacterial protein during 
digestion and manure collection.  The protein component is likely to substitute for adhesives used in 
biocomposite manufacturing, serving as a natural glue similar to many protein-based glues developed in 
the pre-petrochemical age, and new incarnations of these adhesives being developed today (Kuo et al. 
1998, Richard et al. 2002).  Many of the costs of preparing virgin fiber for use in building materials are 
thus already accomplished in the normal course of livestock production – leading us to call this new 
industrial feedstock “Animal Processed Fiber.” 
 
Table 1. Animal Processed Fiber Potential in the U.S. 
 
  Manure Produced 
(dry tons/year) 
Fiber Content 
(as excreted) 
Total Fiber 
(dry tons/year) 
Beef (feedlot only)   12,100,000  44%  5,330,000 
Dairy   23,200,000  42%  9,760,000 
Swine  10,700,000  30%  5,300,000 
Poultry   24,100,000  22%  3,200,000 
Total  70,100,000    23,590,000 
 
 
During the past three years our group has been evaluating bovine manure as a fiber and adhesive 
component in the manufacture of fiberboard. Bovine manure is composed of two 
materials that can function as key components in these engineered fiber products, namely fiber and 
protein. With appropriate processing strategies including solid-liquid separation and drying, these 
fractions could function as feedstocks for a wide variety of purposes including building materials such 
as fiberboard. Figure 1 illustrates the performance of a manure-based particleboard in terms of modulus of rupture 
(MOR, in psi), modulus of elasticity (MOE, x 1000 psi), and internal bonding strength (IB, x 0.02 psi) at 
8 and 10% resin strengths.  The white bar in each category is the ANSI standard for a medium strength 
particleboard.  It is clear that this product can meet these commercial standards, although issues of 
efficient drying and optimum adhesive treatments still need to be addressed. 
 
In the future we may see manure converted into even more valuable products, including proteins for 
animal feed through algael or other microbial conversion processes (Calvert, 1979; Polprasert, 1989; 
Hauck, 1995), and enzymatic conversions to alcohols or other chemical feedstocks (Spellman, 1994).  
While such systems may seem difficult to imagine today, with future research the concentrated energy, 
nutrients and fiber found in livestock manure are certain to be seen as a valuable resource rather than a 
waste. 
 
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0
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A manure management survey of Minnesota swine producers - summary of responses.

A review of recycling organic wastes into fish, with emphasis on the tropics.

Agricultural Residues: a promising alternative to virgin wood fiber.

Animal agriculture must be part of the solution.

Animal Waste Utilization: Effective Use of Manure as a Soil Resource, edited by Ann Arbor Press,

Basis for the control of soilborne plant pathogens with composts.

Biocontrol of foliar fungal diseases with compost extracts. In: Microbial Ecology of Leaves,

Characterization of Volatile Organic Emissions and Wastes from a Swine Production Facility.

Compost tea: principles and practice for plant disease control.

Eliminating Waste: Strategies for Sustainable Manure Management.

Energy production from animal wastes. In: Animal Waste and the Land-Water Interface. Edited by K. Steele. CRC/Lewis Publishers,

Farmers and manure management: A critical analysis. Pp. 1-32 in Animal Waste Utilization: Effective Use of Manure as a Soil Resource, edited by

Feeding broiler poultry litter as an alternative waste management strategy. In: Animal Waste and the Land-Water Interface, edited by K. Steele. CRC/Lewis Publishers,

Feeding processed manure.

Human and animal health aspects of feeding livestock excreta.

IB 8% 10% ANSI(M-S)Calvert, C.C.

Legume-based cropping systems have reduced carbon and nitrogen losses.

Manure Nutrients Relative to the Capacity of Cropland and Pastureland to Assimilate Nutrients: Spatial and Temporal Trends for the United States.

Nutritional and economic value of animal excreta.

Organic Waste Recycling.

Perspective on alternative waste utilization strategies. In: Animal Waste and the Land-Water Interface. Edited by K. Steele. CRC/Lewis Publishers,

Properties of wood/agricultural fiberboard bonded with soybean-based adhesives.

Protein and energy value of dehydrated poultry excreta in diets for feedlot cattle.

Resource or waste? The economics of swine manure storage and management.”

Status of biological control of plant diseases with composts.

Theoretical aspects of methane production: state-of-the-art.

Wood and other raw materials for the 21 st century--Where will they come from.

THINKING OUTSIDE THE BOX: BUILDING MATERIALS AND OTHER PRODUCTS FROM ANIMAL PROCESSED FIBER

THINKING OUTSIDE THE BOX: BUILDING MATERIALS AND OTHER PRODUCTS FROM ANIMAL PROCESSED FIBER

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