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Economics of Manure

Manure contains two key nutrients that support plant growth: nitrogen and phosphorus. Correctly applying manure to croplands can improve the chemical, physical, and biological health of the soil and increase the growth of crops.[1,2]

Before the advent of chemical fertilizers and factory farming, the use of manure was the primary method to fertilize crops. Farms with both animals and crops were the norm, and mixing manure with soils or having grazing animals deposit manure on croplands was the traditional approach.[3]

  1. Rayne, N., & Aula, L. (2020). Livestock Manure and the Impacts on Soil Health: A Review. Soil Systems, 4(4), 64, Abstract. [“…the literature offers convincing evidence of the beneficial impacts of manure on soil and the growth of crops. The degree to which manure affects soil depends on the physical and chemical properties of the manure itself and various management and environmental factors including rate and timing of application, soil type, and climate.”]
  2. Lim, T. et al., (2023) Increasing the Value of Animal Manure for Farmers, USDA Economic Research Service, AP-109, pp. 1-2.
  3. Lim, T. et al., (2023), p. 1. [“In traditional agricultural systems, grazing animals deposit manure on pasture and cropland, effectively recycling many of the nutrients the animal consumed.”]

Not anymore. Most manure on factory farms is considered a liability rather than an asset. Factory farm manure is largely “waste to be managed rather than a nutrient resource.”[1-3]

  1. Swaney, D. P., et al., (2018). Nitrogen use efficiency and crop production: Patterns of regional variation in the United States, 1987–2012. Science of the Total Environment, 635, 498-511, Abstract. [“…in the US, manure is still treated largely as a waste to be managed rather than a nutrient resource.”]
  2. Long, C. M., et al., (2018). Use of manure nutrients from concentrated animal feeding operations. Journal of Great Lakes Research, 44(2), 245-252. p. 6. [“Because more manure is generally produced by a CAFO than can easily be used, it is often treated as waste rather than as a valuable replacement for inorganic fertilizer.”]
  3. Ribaudo, M. O., et al., (2003). Land application of manure by animal feeding operations: Is more land needed? Journal of Soil and Water Conservation, 58(1), 30-38, p. 2. [“As confined operations become larger and feed is supplied from outside the region, animal manure is likely to be viewed more as a disposal problem than as a nutrient resource.”]

The many reasons that factory farm operators and crop producers see manure as a liability include:[1-7]

Chemical Fertilizer Availability – Chemical fertilizer is more economical for crop producers, better matches the nutrient requirements of the crops, is easier to apply, and leads to larger and more predictable yields.
Concentration – The huge amounts of manure produced in a single location do not match up to the limited nutrient requirements of nearby croplands.
Transport costs – Manure is heavy, often with high water content. Transport is expensive, severely limiting the potential radius of use.
Complex transactions – The de-coupling of livestock and crop production often makes complex and inconvenient inter-farm transactions necessary.
N & P imbalance – Most manure is phosphorus-heavy and nitrogen-light, compared to crop needs. This is exacerbated by volatilization of nitrogen in manure storage systems.
Unpredictable supply – The availability of manure can be unpredictable compared to purchasing chemical fertilizers; nutrient application must occur during a small timeframe.
Unpredictable content -The levels and proportions of nutrients in manure vary and must be tested off-site for effective application.
Contaminants – Manure often has high levels of contaminants, including antibiotics, hormones, heavy metals, and pathogens, along with weed seeds.
Regulations – Users have concerns about state or federal regulations or challenges from local homeowners.
 Marketing – Chemical fertilizers are heavily promoted as technologically superior; manure has no corporate sponsors.

Dairy and pig manure generally has the least value, and poultry manure the most because it is usually dry, more concentrated, and therefore more economical to transport.[8]

  1. Kleinman, P. J. A., et al. (2022). Envisioning the manureshed: Toward comprehensive integration of modern crop and animal production. Journal of Environmental Quality, 51(4), 481, p. 483. [“Further, variability in manure quality between and within livestock operations challenges manure’s predictability as a fertilizer. So too does inconsistency in testing procedures… Manure nutrient ratios often do not match those required by crops… Manure can serve as a vector for pathogens (plant and animal) as well as for weeds… measures generally come at costs not associated with commercial fertilizers.”]
  2. Lim, T. et. Al (2023) Increasing the Value of Animal Manure for Farmers, USDA ERS, AP-109, pp. 2-12. [“The low quantity of nutrients per ton, relative to commercial fertilizers, results in time-intensive and costly transportation. Depending on the weather, in any year, farmers may have a few days with suitable conditions that allow them to prepare fields, spread fertilizer, and plant. Crop planting takes priority, so to save time, farmers may choose commercial fertilizers rather than manure. Second, manure as excreted and after storage has a nitrogen-to-phosphorus ratio that does not align with most crops’ nutrients requirements… Manure nutrient levels vary within and across farms, so manure must be tested to be used efficiently. Manure tests measure the nitrogen and phosphorus in manure samples and have typically required sending samples to a laboratory.”]
  3. Waller, D. M., et al., (2021). Shifts in precipitation and agricultural intensity increase phosphorus concentrations and loads in an agricultural watershed. Journal of Environmental Management, 284, 112019, p. 2. [“Because manure spreading typically occurs within an economic hauling radius (<3–10 miles under most Wisconsin permits), CAFOs have an incentive to overapply manure to save on transport and distribution costs….Large manure lagoons must be emptied or managed regularly, creating incentives to spread manure at times and at levels that may not be optimal for crop production…”]
  4. Zhang, H., & Schroder, J. (2014). Animal manure production and utilization in the US. In Applied manure and nutrient chemistry for sustainable agriculture and environment (pp. 1-21). Dordrecht: Springer Netherlands, p. 9. [“For example, the N:P ratio of most poultry litter and feedlot manure is close to 2:1, but most crops require an N to P ratio of 8:1. Therefore, while N and some P are used by the crops, most of the excess P stays in the soil.”]
  5. Ribaudo, M., et al., (2003) Manure Management for Water Quality: Costs to Animal Feeding Operations of Applying Manure Nutrients to Land. USDA ERS No. 824, p. 21. [“There are several potential drawbacks to land application of manure that could discourage greater use on cropland. These factors include uncertainty associated with the nutrient content and availability, high transportation and handling costs relative to commercial fertilizer, soil compaction from spreading equipment, dispersion of weed seeds, concerns about added regulatory oversight, and public perception regarding odor and pathogen issues.”]
  6. U.S. EPA (2013) Literature Review of Contaminants in Livestock and Poultry Manure and Implications for Water Quality, EPA 820-R-13-002, p.1. [“Manure often contains pathogens (many of which can be infectious to humans), heavy metals, antimicrobials, and hormones that can enter surface water and ground water through runoff and infiltration potentially impacting aquatic life, recreational waters, and drinking water systems.”]
  7. Keplinger, K. O., & Hauck, L. M. (2006). The economics of manure utilization: model and application. Journal of Agricultural and Resource Economics, 414-440, p. 415. [“When supplies of manure become large, its value falls and an incentive is created to apply manure at rates exceeding crop requirements or to otherwise dispose as inexpensively as possible, despite negative externalities. Consistent with externality theory, degradation of public resources (air and water) has occurred in regions of the country with high concentrations of livestock.”]
  8. Keplinger, K. O., & Hauck, L. M. (2006), Figure 2, p. 427.

The combination of manure’s negative value and the lack of enforceable regulations[1,2] makes manure dispersal and its accompanying nutrient pollution a rational economic choice for factory farm operators.[3,4]

Nutrient pollution from animal agriculture – factory farm manure and fertilizers on feed crops – is undoubtedly the single largest cause of impaired U.S. waterways along with many other negative impacts.[5]in Livestock and Poultry Manure and Implications for Water Quality, EPA 820-R-13-002.

  1. Rosov, K., et al. (2020). Waste nutrients from U.S. animal feeding operations: Regulations are inconsistent across states and inadequately assess nutrient export risk. Journal of Environmental Management, 269, 110738.
  2. U.S. EPA (2022) EPA Legal Tools to Advance Environmental Justice, Pub. No. 360R22001, p. 75. [“Many CAFOs are not regulated and continue to discharge without NPDES permits because successive court decisions have severely limited EPA’s ability to require CAFOs to obtain an NPDES permit.”]
  3. Del Rossi, G., et al., (2023). The economics of nutrient pollution from agriculture. Annual Review of Resource Economics, 15(1), 105-130, p. 107. [“In short, rather than seeing this as economically suboptimal, nutrient pollution from agriculture should be considered as a standard environmental externality. Agricultural enterprises optimize their private net benefits and ignore the social costs from nutrient pollution in the environment.”]
  4. Kleinman, P. J., et al., (2020). Managing animal manure to minimize phosphorus losses from land to water. In Animal manure: Production, characteristics, environmental concerns, and management, 67, 201-228, p. 219. [“Many options exist to better manage manure, and, more specifically, P in manure, to minimize their impact on water quality. However, doing so requires comprehensive approaches that consider factors far beyond the direct handling of manure and require decisions that may compete or conflict with other priorities, most notably profits and time management.”]
  5. See, Nutrient Pollution and Animal Ag Overview

Manure management on factory farms includes:

Unmanageable volumes – A typical pig factory farm with 30,000 pigs generates more than 900 tons (1.8 million pounds) of manure per week, about equal to the weekly human waste from a small city of 80,000 people.[1,2]

Storage infrastructure – Building, maintaining, and improving manure storage infrastructure is a major expense for factory farms. Manure lagoons leak, pipes break, and unusual weather events cause major disruptions.[3,4]

Dangerous gases threaten human and animal health – Concentrated manure on factory farms generates enormous amounts of dangerous gases that can sicken or kill animals and workers.[5] Expensive ventilation systems have to run 24/7 to remove heat and gases. Mortalities for animals and humans are common.[6]

Contaminants including pathogens – As the EPA notes, the long list of manure contaminants includes “pathogens (many of which can be infectious to humans), heavy metals, antimicrobials, and hormones that can enter surface water and ground water through runoff and infiltration potentially impacting aquatic life, recreational waters, and drinking water systems.”[7]

Transportation – Manure is heavy and transportation costs are high.[8] To move the weekly manure generated from a typical pig farm of 30,000 pigs would require about 30 transport loads with a very large 30-ton spreader, with significant costs for machinery and labor.[9]

Land Management – Most factory farm operators must own, rent, manage, or contract with nearby cropland for the express purpose of dispersing their manure.[10]

  1. See, Pig Factory Farm Sizes
  2. Kellogg, R. L., et al. (2014). Estimates of recoverable and non-recoverable manure nutrients based on the census of agriculture. USDA Natural Resources Conservation Service. [Calculation: A typical pig farm holds about 30,000 pigs, which is about 3,300 “animal units” generating about 14.7 tons of manure per year for each AU. 3,300 * 14.7 / 52 = 933 tons of manure per week. For animal units, see Table 1, p. 4 (using 9.1 for “Hogs for Slaughter.”) For manure generated per AU, see Table 5, p. 33. Human waste = 80,000 x 3.33 lbs. x 7 = 932 tons.]
  3. Rudko, N. et al. (2023). Development of a point-source model to improve simulations of manure lagoon interactions with the environment. Journal of Environmental Management, 325, 116332, p. 2. [“Moreover, it is well known that lagoons interact with groundwater and can cause elevated
  4.  Harris, R. A., et al., (2021) Microbial Contamination in Environmental Waters of Rural and Agriculturally-Dominated Landscapes Following Hurricane Florence. ACS EST Water, 1, 9 2012-219, Abstract. [“These results suggest that improved swine and human feces management should be explored to prevent microbial contamination in surface water, especially in regions where extreme rainfall may increase due to climate change.”]
  5.  Aneja, V. P., et al., (2009). Effects of Agriculture upon the Air Quality and Climate: Research, Policy, and Regulations. Environmental Science & Technology, 43(12), 4234–4240, p. 4236. [“Animal production results in emissions of hundreds of identified VOCs (volatile organic compounds)… Hydrogen sulfide, a major emission from animal agriculture, is a colorless, potentially lethal gas released from swine manure decomposition.”]
  6.  Nour, et al. (2019). Development of methodology to document and code farm-related injuries and fatalities involving manure storage, handling and transport – with summary of 2017 incidents. Journal of Agromedicine, 24(1), 90–100, p. 92.
  7.  U.S. EPA (2013) Literature Review of Contaminants in Livestock and Poultry Manure and Implications for Water Quality, EPA 820-R-13-002, p.1. [“Manure often contains pathogens (many of which can be infectious to humans), heavy metals, antimicrobials, and hormones that can enter surface water and ground water through runoff and infiltration potentially impacting aquatic life, recreational waters, and drinking water systems.”]
  8. Waller, D. M., et al., (2021). Shifts in precipitation and agricultural intensity increase phosphorus concentrations and loads in an agricultural watershed. Journal of Environmental Management, 284, p. 112019. [“Because manure spreading typically occurs within an economic hauling radius (<3–10 miles under most Wisconsin permits), CAFOs have an incentive to overapply manure to save on transport and distribution costs.”].
  9. Pik Rite Inc. Manure Spreaders https://www.pikrite.com/spreaders/
  10. EPA (2012) NPDES Permit Writers’ Manual for CAFOs, EPA-833-F12-001, p. 4-3. [“The land application area means all land under the control of the CAFO owner or operator, including where the CAFO owns, rents, or leases the land to which manure from the production area is applied. 40 CFR § 122.23(e)(3). It includes situations where a CAFO determines when and how much manure is applied to fields not owned, rented, or leased by the CAFO.”]

For economic viability and for regulatory purposes, factory farm operators must own, rent, manage, or contract with nearby cropland for the express purpose of dispersing their manure.[1-4]

For operators designated by the EPA as CAFOs, sufficient land must be “under the control” of operators through ownership, rentals, leases, contracts, or easements.[5,6] Nutrient management plans are to include site-specific terms for manure land application.[7]

The USDA reports that nationally 78% percent of manure is applied to land controlled by farmed animal producers.[8]

Despite these contracts and regulations, USDA scientists note that, “Farms with confined animals generally have inadequate cropland to assimilate nutrients produced and are characterized by excess nutrient applications on cropland they control.”[9]

  1. Miralha, L., et al., (2021). Spatiotemporal land use change and environmental degradation surrounding CAFOs in Michigan and North Carolina. Science of the Total Environment, 800, 149391. Highlights and p. 2. [“Lands near CAFOs changed to cropland, likely to meet manure application needs … To meet state and federal waste management regulations, CAFO operators must either acquire or rent sufficient land nearby for applications, or transfer or sell manure to nearby farms”]
  2. Kleinman, P. J., et al., (2020). Managing animal manure to minimize phosphorus losses from land to water. In Animal manure: Production, characteristics, environmental concerns, and management, 67, 201-228 p. 205. [“Increasingly, in vertically integrated industries with a high degree of strategic coordination (e.g., poultry and swine), new operations are not even designed to land apply manure that is produced and manure export may be required in a contract.”]
  3. Deviney, A., et al., (2020). Sustainable swine manure management: A tale of two agreements. Sustainability, 13(1), 15. [“Additionally, as the number of farms in a region increases, the availability of local land to irrigate or spread manure on decreases. This trend is further exacerbated by competition for manure spreading acres with other livestock production …”]
  4. USDA (August 2018) Nutrient Management Practices on U.S. Dairy Operations, 2014 National Animal Health Monitoring System, Report 4, p. i. [“Overall, 90 percent of operations applied manure to land either owned or rented.”] (under USDA dairy)
  5. EPA (2012) NPDES Permit Writers’ Manual for CAFOs, EPA-833-F12-001, p. 4-3. [“The land application area means all land under the control of the CAFO owner or operator, including where the CAFO owns, rents, or leases the land to which manure from the production area is applied. 40 CFR § 122.23(e)(3). It includes situations where a CAFO determines when and how much manure is applied to fields not owned, rented, or leased by the CAFO.”]
  6. Boessen, C., & Massey, R (2003). Securing manure spreading rights through easements. Univ. of Missouri. [“With a manure easement, a landowner conveys to a livestock producer the right to spread manure on a specified tract of land for a specified period of time.”]
  7. U.S. EPA (2012) NPDES Permit Writers’ Manual for CAFOs, p. 4-3. [“The NMP must identify each field where land application will occur. The CAFO regulations require each field included in the NMP to be a site-specific term of the permit.”]
  8. Lim, T., et. al., (2023) Increasing the Value of Animal Manure for Farmers, USDA ERS, AP-109, p. 16. [“For all crops, 78 percent of manure is applied to land controlled by the animal producer…”]
  9. Ribaudo, M., et al. (2017). The potential role for a nitrogen compliance policy in mitigating Gulf hypoxia. Applied Economic Perspectives and Policy, 39(3), 458-478, p. 12.

Yes, and sometimes it is even acknowledged as such.[1]

By the time the manure is land-applied, it has very low nitrogen levels, the key crop nutrient required.[2] About half the time, manure is applied in addition to the full application of chemical fertilizers.[3-5] Most of the time, manure is not incorporated into the soil, ensuring runoff.[6]

In summary, land application is usually a method to get rid of a waste product.

  1. Capel, P. D., et al., (2018)  Agriculture—A River runs through it—The connections between agriculture and water quality, U.S. Geological Survey Circular 1433, 201, p. 116. [“Applying manure to fields also is a practical method for disposing of animal waste, but manure typically contains metals, antimicrobials, hormones, bacteria, and pathogens.”]
  2. U.S. EPA (2002) Non-Water Quality Impact Estimates for Animal Feeding Operations, pp. 1-2. [“Nitrogen losses from animal manure as ammonia can easily exceed 50 percent.”]
  3. Lim, T., et al., (2023) Increasing the Value of Animal Manure for Farmers, USDA ERS, p. 12. [“USDA ARMS data indicate that only 44 percent of farmers who applied manure to corn also reduced commercial fertilizer applications to corn because of manure applications.” About 80% of manure is applied to corn.]
  4. Hellerstein, D., & Vilorio, D. (2019). Agricultural resources and environmental indicators, 2019, USDA, p. 77 and Table 2-14-2 on p. 78. [“About 43 percent of all dairy operations adjusted their fertilizer nutrients, compared to 31 percent of hog operations and 14 percent of broiler operations.” In other words, about two-thirds of operations applied the full application of chemical fertilizers, despite adding manure nutrients.]
  5. Leytem, A. et al., (2021). Cycling Phosphorus and Nitrogen through Cropping Systems in an Intensive Dairy Production Region. Agronomy (Basel), 11(5), 1005, p. 10. [“This suggests that not only are manure nutrients undervalued but they are not likely included in calculating nutrient budgets, which can lead to overapplication of N and P, particularly on fields receiving manure.”]
  6. Lim, T., et al., (2023), p. 22 and Figure 9. [“For all types of manure, surface application with or without incorporation is the most frequently used method of application… Less than 30 percent of surface-applied manure is incorporated into the soil.”]

If manure management practices were limited by stringent and enforceable regulations, the costs of production for factory farms would rise significantly, retail prices would rise, and demand would slightly fall due to higher prices.[1]

However, viewed through the wider lens of the overall costs to society, total costs would fall. Currently the high costs of water pollution, like all negative externalities, are being borne by non-consenting third parties.[2]

As one report notes: “Once released to the environment, N and P are costly to control.”[3] Like all pollution, the impacts can be mitigated at a much lower cost before the pollutants leave the source.[4]

  1. Marc Ribaudo, et al., (2003). Manure Management for Water Quality: Costs to Animal Feeding Operations of Applying Manure Nutrients to Land. USDA ERS, Report 824, p. iii. [“If all CAFOs meet the nutrient standards outlined in the new regulations, increases in production costs could be felt throughout the food and agricultural system.”]
  2. See, Animal Ag Externalities
  3. Del Rossi, G., et al., (2023). The economics of nutrient pollution from agriculture. Annual Review of Resource Economics, 15(1), 105-130, p. 122.
  4. Pretty, J., et al., (2001). Policy challenges and priorities for internalizing the externalities of modern agriculture. Journal of environmental planning and management, 44(2), 263-283, p. 269. [“An important principle is that it is more efficient to use limited resources to promote practices that do not damage the environment than to have to spend them on cleaning up after a problem has been created.”]

Yes, in some ways. Both products have extremely low rates of recycling. Post-consumer plastics are recycled at rates under 10% in the U.S.[1] The nutrients in manure are recycled (effectively applied to croplands) at a similar rate.[2]

The reasons why nutrients in manure don’t get recycled are similar to the reasons why plastics don’t get recycled.[3,4]

It is cheaper to create new product (chemical fertilizer or new plastics) than recycle the old.
The new product is better suited to production needs.
The makeup of the old product is unpredictable; there are different types of plastics and inconsistent nutrient levels in manure.
The costs associated with handling the old product – aggregating, storage, transportation – cannot be offset by the value of reuse.
Enforceable regulations are lacking.
Both products are widely dispersed across the nation.

  1. Milbrandt, A., et al., (2022). Quantification and evaluation of plastic waste in the United States. Resources, Conservation and Recycling, 183, 106363, Abstract. [“Of the estimated 44 Mt of plastic waste managed in 2019 domestically, approximately 86% was landfilled, 9% was combusted, and 5% was recycled.”]
  2. See, Total Manure Nutrient Pollution
  3. Vogt, B. D., et al., (2021). Why is recycling of postconsumer plastics so challenging? ACS Applied Polymer Materials, 3(9), 4325-4346.
  4. U.S. EPA (April 15, 2025) Plastics: Challenges. https://www.epa.gov/plastics/challenges

Manure & Other Outputs