Five years after EWG’s first analysis, manure still overloads Minnesota

Massive quantities of manure from food production in Minnesota pollutes drinking water, posing a significant health risk. Livestock facilities in the state generated almost 49 million tons of manure in 2024, a new EWG analysis finds.

It’s a long-running problem that EWG highlighted in a 2020 investigation. Five years after that report, this new analysis finds only a slight downtick in the number of animal facilities, from 23,725 in 2019 to 23,503 in 2024, and a similarly small decrease in the amount of manure they produce. The waste they generate is equivalent to almost 8.5 tons of manure yearly for every Minnesotan.

But cattle production has become more concentrated at the largest facilities, which have increased in number by over 12 percent. Many meat and animal products sold in the U.S. come from livestock raised in animal facilities, which produce hundreds or thousands of hogs, poultry or cattle in concentrated barns or feedlots.

The enormous amounts of manure these facilities generate are often applied to nearby farm fields as a fertilizer, since the nitrogen and phosphorus it contains are nutrients that feed crops. But manure and its components can wash off farm fields, leach through soil into drainage systems that empty into nearby streams, or get into groundwater.

Nitrogen can form in drinking water as nitrate, and consuming this water can increase the risk of birth defects and cancer. Manure runoff can also create potentially toxic algae blooms in recreational waters when nutrients are applied in excess of crops’ uptake capacity. EWG has previously reported on algae toxins in bodies of water throughout Minnesota.

Changes at the federal and state level could help tackle this problem. At the federal level, much less conservation funding should go to structural practices for animal feeding operations, or AFOs. These practices include waste storage facilities and covers for manure pits, which encourage more production and waste.

At the state level, Minnesota could more strictly regulate AFOs to reduce the risk of animal manure polluting water. One option is to regulate facilities that fall below the Environmental Protection Agency’s threshold for Clean Water Act discharge permits.

Risk of nitrogen overload

At the largest livestock facilities, known as concentrated animal feeding operations, or CAFOs, the risk of over-application increases. That’s because there is limited cropland nearby, and transporting the waste elsewhere is often difficult and expensive.

EWG also analyzed which fields near AFOs likely received manure in 2024. Analysis found hot spots – areas most at risk for overapplication of manure.

The analysis found nine counties that are hot spots for nitrogen overload. This happens when nitrogen from manure, combined with nitrogen in fertilizer sold in the county, exceeds crop recommendations by more than 40 percent.

Nitrogen overload can be a particular problem in “vulnerable groundwater areas,” as defined by the Minnesota Pollution Control Agency, or MPCA. In these areas, nitrate applied to farm fields through fertilizer or manure can easily get through soil and pollute groundwater. In 2024, 6,480 animal feeding operations were located within a vulnerable groundwater area. (See Figure 1.)

Figure 1. Minnesota counties and vulnerable groundwater areas at risk of nitrogen overload

Map of Minnesota showing vulnerable groundwater areas and counties overloaded with nitrogen in purple.

^{Source: EWG, from MPCA vulnerable groundwater area dataset}

Water contamination threatens Minnesota’s drinking water, recreational water and public health. Consolidating animal production in large CAFOs intensifies that risk.

Huge amounts of manure

EWG’s analysis finds that Minnesota had 23,503 animal feeding operations in 2024. These facilities house up to 1.03 million dairy cattle, 1.6 million beef cattle, 10.8 million hogs and 58.7 million turkeys and chickens, which together produced over 48.9 million tons of manure that year.

Cattle make up most operations in the state and account for over 64 percent of manure, while swine are 27 percent and poultry 8 percent. (See Figure 2.)

Figure 2. Cattle operations produce most of the manure in Minnesota

Pie chart showing livestock distribution: Cattle 64.4%, Swine 27.4%, Poultry 8.2%.

^{Source: EWG, from Manure Characteristics Midwest Plan Service, or MWPS, 18 Section 1, 2004, Second Edition}

Stearns, Todd, Goodhue, Fillmore and Winona counties (in order of most to least) had the most animal feeding operations in 2024, representing 25 percent of all facilities in the state. (See Figure 3.)

Most livestock facilities in the state are small, but the large facilities produce a disproportionate amount of manure. We used the EPA’s CAFO definitions for this report. Small facilities have fewer than 300 animal units, medium facilities have between 300 and 999, and large have 1,000 or more animal units.

An “animal unit” is defined as an animal equivalent to 1,000 pounds live weight. For example, a single animal unit would be one beef cattle, 2.5 hogs or 125 chickens. So large facilities, or CAFOs, have at least 1,000 beef cattle, 2,500 hogs or 125,000 chickens.

While 78 percent of facilities were small, they produced just 24 percent of manure. Medium facilities made up only 18 percent of all operations but produced the largest share of manure, at 43 percent. Four percent of facilities were large but generated 33 percent of manure.

Figure 3. Map of Minnesota’s animal feeding operations in 2024 by animal type and county

Map of Minnesota showing animal types by location: beef (blue), dairy (yellow), poultry (orange), swine (red).

^{Source: EWG, from MPCA feedlot dataset}

Cattle production is getting more concentrated in the largest facilities in Minnesota. There were 22 more large cattle facilities in 2024 than in 2019 – a 12 percent increase in CAFOs with 1,000 or more animal units. The number of large swine facilities stayed the same, while the number of large poultry facilities decreased slightly.

For both cattle and swine, the average number of animal units per facility also increased in 2024 for the largest facilities – some of the biggest CAFOs are getting even bigger. The average number of animal units per facility increased by 257 between 2019 and 2024 in the case of large cattle facilities. The average went up by 24 animal units per facility for large swine operations.

Regulation falling short

In Minnesota, large animal feeding operations must have either an EPA Clean Water Act National Pollutant Discharge Elimination System permit or a state-based State Disposal System permit to operate.

The permits require these large operations to create and submit to the state a manure management plan showing which farm fields livestock operators plan to apply their manure to each year. Permitted facilities must also follow certain land application restrictions to protect vulnerable groundwater areas.

Management plans aim to prevent multiple facilities from applying manure to the same fields, applying manure above the agronomic rate, or both.

These plans are far from perfect and poorly enforced, which is why manure overapplication is still common near large facilities in many areas of the state. But manure management plans, along with the other regulations that apply to large facilities, do rein in some of the worst potential pollution.

Facilities that house between 300 and just under 1,000 animal units do not need a water pollution permit. Minnesota requires only that they get a construction permit. So these medium-sized facilities are not subject to other rules that could protect water quality and public health, such as those that apply to large CAFOs.

In Minnesota, 983 facilities housed between 750 and 999 animal units – just a few hundred units under the 1,000 level that requires regulation. These facilities still produced a lot of manure, as they are 14 percent of all facilities in the state, but are barely regulated. And among these, there were 374 operations that were between 950 and 999 animal units - just 50 animal units short of the large CAFO designation. So almost 400 facilities are polluting at levels close to the amounts from large facilities, but are not regulated in the same way, though they should be.

Manure application hot spots

EWG simulated which individual fields could safely accept manure, based on their distance from the feedlot and the amount of nitrogen recommended for growing crops. Nitrogen rates were based on MPCA guidelines and University of Minnesota fertilizer recommendations.

In areas with a dense concentration of livestock, almost all crop fields are needed to achieve safe use of manure produced by nearby feedlots. In a few isolated areas, there is too much manure to dispose of within a reasonable distance.

EWG’s simulation likely understates the risk of this overload, because we assumed every field within 5 miles of a cattle or hog feedlot and 25 miles of a poultry feedlot is available to take manure, while in most real situations, manure does not travel that far.

There are nine county hot spots for nitrogen overload, where nitrogen from manure combined with nitrogen in fertilizer sold in the county exceeded crop recommendations by more than 40 percent. (See Table 1.)

Table 1. Counties with nitrogen overload

County	Percent nitrogen recommendation met by fertilizer sold	Percent nitrogen recommendation met by applied manure	Percent nitrogen recommendation met by manure and fertilizer combined
Cass	84.1	74.5	158.7
Carlton	84.1	72.1	156.2
Morrison	84.1	69.9	154.0
Martin	89.4	61.2	150.7
Winona	100.9	49.6	150.6
Hubbard	84.1	61.4	145.5
Rock	77.6	66.2	143.9
Clearwater	126.8	15.9	142.7
Stearns	84.1	57.6	141.7

^{Source: EWG, from Manure Characteristics MWPS-18 Section 1 Midwest Plan Service, 2004, Second Edition and MPCA feedlot dataset}

Research shows that much of the nitrogen considered lost to the atmosphere during manure storage and application ends up redeposited on the land nearby, adding to the potential overload. The concentration of feedlots leaves little or no room to adapt to year-to-year changes in cropping patterns and fluctuating manure composition. It also increases the risk of overloading fields with phosphorus.

Many counties with nitrogen overload, highlighted in Figure 4 below with black outlines, are within the Central Sands and Southeast regions of Minnesota. These two regions have a high percentage of land with the MPCA vulnerable groundwater area distinction.

Figure 4. Areas in Minnesota with nitrogen overload from manure

Map of Minnesota showing counties with nitrogen overload, eligible cropland, and manure satisfaction areas.

^{Source: EWG, from MPCA feedlot dataset}

When manure is applied to meet the nitrogen recommendation for crops, phosphorus is often overapplied. This nutrient imbalance is worse for poultry and cattle manure. Phosphorus overload in Minnesota is common – a problem since phosphorus is a major driver of toxic algae blooms.

Algae blooms in recreational water sources can pose a health hazard for humans and pets, not to mention the ecosystem harm. When applying manure at a nitrogen fertilizer rate, the phosphorous content of the manure often exceeds plant need.

The state’s newly updated permitting regulations will determine when large facilities in vulnerable groundwater areas can apply manure to nearby fields. But out of the 6,480 operations in a vulnerable groundwater area, only 161 are above the 1,000 animal unit threshold.

Almost five times that number (791 facilities) fall into the medium category – with more than 300 animal units but fewer than 1,000 animal units. The rest of the facilities do not have rules about how much manure they can apply to vulnerable fields or when. And 53 of these facilities have slightly fewer than 1,000 animal units. So they produce a lot of manure in vulnerable groundwater areas without being subject to the large CAFO rules.

Reforms to help reduce pollution

Minnesota has long struggled with nitrate in drinking water, especially in the Southeast portion of the state. This region has karst soils that water and contaminants can easily leach through, making groundwater more vulnerable to nitrate contamination. Private wells in the region and in other areas of Minnesota have levels of nitrate in their drinking water that are dangerous for the people who rely on them.

EWG joined the Minnesota Center for Environmental Advocacy in 2023 to petition the EPA to work toward fixing the groundwater nitrate contamination crisis in this region.

Livestock facilities also damage air quality, emitting pollutants like ammonia, hydrogen sulfide and particulate matter. This air pollution can cause respiratory illnesses like asthma and bronchitis in people living nearby. And studies show that people who live within a few miles of an AFO have increased rates of mortality from respiratory and cardiovascular problems.

Food production should not imperil water quality and public health.

Reform of federal conservation programs to reduce how much money goes to structural practices for animal feeding operations would be a good first step. The Department of Agriculture’s Environmental Quality Incentives Program, or EQIP, is one of the largest federal conservation programs. This program requires half of all funding to go to farmers for livestock practices. It sent over $1.3 billion to farmers in 2024.

Reforms could include:

Exempting states from the requirement that 50 percent of EQIP dollars go toward livestock production.
Lowering the payment limit from $450,000 to $250,000 to prevent a few large producers from monopolizing EQIP funds.
Barring the largest CAFOs from receiving funding for upgrading or installing infrastructure equipment.

Additionally, the state of Minnesota should change how it regulates AFOs to reduce the risk of pollution of water with animal manure, adopting these policies:

Permitted, large facilities should be required to monitor subsurface discharges to see how much nitrate ends up in water. There is currently no way to make sure these operations do not violate Minnesota’s water quality standards.
Facilities that are under 1,000 animal units but still produce huge amounts of manure, such as those between 750 and 999 animal units, should be required to get a State Disposal System permit.

We’re in this together

Donate today and join the fight to protect our environmental health.

Donate

Methodology

Special thanks to Sarah Porter, previously with EWG

Introduction

Adequately addressing water quality issues in Minnesota requires a better understanding of the relative contribution of the major nutrient sources and their distribution.

Consolidation of animal operations has created landscape scenarios in which large quantities of manure are produced in geographically clustered areas. Losses of nitrogen, or N, and phosphorus, or P, the two primary nutrients in manure, can contaminate surface water and groundwater. This leads to a wide range of environmental and economic consequences.

The following EWG analysis attempts to improve our understanding of the relative contribution of commercial fertilizer and livestock manure to nutrient loading in Minnesota.

EWG used geospatial techniques to quantify the capacity of the landscape to uptake manure nutrients while identifying areas of manure saturation in the state.
Commercial fertilizer sales data were combined with manure-sourced nutrient estimates to assess nutrient application relative to crop fertilizer recommendations at the statewide and county level.

Animal feedlots

The Minnesota Pollution Control Agency, or MPCA, maintains a database of feedlots¹ in the state housing 50 or more animal units. Animal units, or AU, are used to compare differences in the production of animal manure among livestock types (1 AU equals 1,000 pounds of animal weight).² The MPCA publishes this feedlot registration as a geospatial dataset that EWG downloaded from the Minnesota Geospatial Commons on September 17, 2024.

The dataset included general information for 23,503 active operations housing a dominant livestock group, including poultry (layers, broilers and turkeys), swine, and beef and dairy cattle.

Modeling landscape capacity For manure nutrients

EWG employed a GIS program developed by Porter and James³ to spatially model the capacity of neighboring cropland to incorporate manure nutrients. Detailed estimates of manure and nutrient excretion were made for all 23,503 active feedlots in Minnesota.

Nitrogen loss was accounted for during manure storage and handling and upon application to determine the amount of manure nutrients available for land application on an annual basis. The N requirement of agricultural fields was estimated using six-year crop rotations and commonly used guidelines on fertilizer recommendations for agronomic crops. Manure was applied to fields to meet the N requirement of growing crops. P was applied at the same time according to the calculated N to P ratio of each feedlot.

Lastly, manure nutrients were combined with county-level commercial fertilizer sales to allow for an estimate of nutrient supply relative to crop requirements at a county level.

Estimating nutrients from feedlots

Animal counts listed for each facility represent the maximum number of animals that may be housed at that location and may not accurately reflect the actual number of animals at any given time. This is particularly true for smaller operations. To account for this, animal counts were reduced for facilities below 300 animal units using the following adjustment factors: 90 percent for dairy and swine, 70 percent for beef, 80 percent for turkey and 85 percent for chickens.

The amount of manure, N, and P excreted annually from each active feedlot was calculated using book values from the Midwest Planning Service, or MWPS, 18 Second Edition (2004).⁴ Each type of animal in the Minnesota feedlot database was matched to an animal type from the MWPS (see Table 2) to calculate daily excretion values for manure, N and P. MWPS values were averaged when an exact match to an animal type could not be made.

Daily excretion amounts were multiplied by 365 days to estimate annual excretion amounts. Although the MWPS is commonly used to estimate manure nutrient content, book values provide estimates only. The actual characteristics of manure can vary by 30 percent due to genetics, diet and farm management.

A study by Porter and James (2020)³ applied the average of MWPS finishing swine categories (weights from 150 to 300 pounds, with an average of 220 pounds) to all medium swine in the Minnesota feedlot database. However, the MPCA routinely assigns a 150 pound weight to medium swine, assuming a grow-to-finish operation with pigs averaging between 55 and 300 pounds.

As the manure and nutrient values for a 220 pound hog are approximately 40 percent greater than values for a 150 pound hog, these differences can be significant, particularly for the state’s dominant swine production system. EWG ran the model using values representing the low end (150 pounds for all grow-to-finish swine) for nutrient values.

But manure nutrient contents can vary widely among all livestock types.⁵ Ideally, a sensitivity analysis using different parameters would provide a full range of manure application scenarios.

Porter and James (2020)³ assessed the sensitivity of this approach to changes in N application rate and travel distance in Minnesota. They found that the extent of land area receiving manure, as well as the potential risk of overapplication, will expand and contract depending on which parameters are used, although the spatial patterns remain consistent.

When varying manure-haul distance and N application rate, Porter and James (2020)³ found that total N applied in Minnesota (from both manure and commercial fertilizer sources) was between 110 percent and 155 percent of recommendations.

Table 2: Minnesota manure and nutrient excretion values (in pounds/animal/day) as adapted from MWPS-18, 2004.

Animal type	MWPS animal type	Manure	N	P
Dairy cattle, large	Combination lactating (305 days) and dry cow (60 days) (1,400 lb)	142	0.92	0.203
Dairy cattle, small	Combination lactating (305 days) and dry cow (60 days) (1,000 lb)	101	0.65	0.145
Dairy heifer	Average of 750 and 1,000 lb dairy heifer	53	0.265	0.0396
Dairy calf	Average of 150 and 250 lb dairy calf	16	0.085	0.007
Beef steer/stock	Finishing cow (1,100 lb)	54	0.4	0.053
Beef feeder/heifer	Average of finishing cow (750 lb) and cow in confinement	64.5	0.31	0.057
Beef cow/calf pair	Sum of cow in confinement and beef calf (450 lb)	140	0.55	0.119
Beef calf	Average of 450 and 650 lb beef calf	58.5	0.245	0.048
Swine, large	Average of all swine > 300 lbs	13.4	0.113	0.034
Swine, medium	Average of 150 to 300 lb finishing swine (Porter and James, 2020)	11	0.128	0.02
150 lb finishing swine (MPCA)	7.4	0.09	0.0132
Swine, small	Average of 25 and 40 lb nursery swine	2.5	0.025	0.004
Turkey, large	Male turkey (20 lbs)	0.74	0.0111	0.003
Turkey, small	Female turkey (10 lbs)	0.47	0.0078	0.002
Layer, large	Layer (3 lbs)	0.15	0.0026	0.0004
Layer, small
Broiler, large	Broiler (2 lbs)	0.19	0.0021	0.0006
Broiler, small
Chicken liquid manure	Layer (3 lbs)	0.15	0.0026	0.0004

^{Source: EWG via Midwest Plan Service}

Many cattle feedlots in Minnesota use a combination of confinement buildings and pasture. Manure that is excreted in a pasture is assumed to be unrecoverable. As-excreted amounts of manure, N and P were reduced by 50 percent for all cattle operations below 300 AU and with a “pasture” flag in the feedlot database. This factor was applied to beef and dairy cattle operations in the state and significantly reduced the manure contribution from smaller cattle and dairy operations, particularly in areas with large amounts of pasture and other grasses or hay.

Much of the N excreted in manure is lost to the atmosphere, primarily as ammonia, during manure storage, handling and field application. Although not accounted for in this study, there is evidence that much of this volatilized N is redeposited to the land surface within 1 kilometer of the confinement.⁶ The amount of N loss depends on several factors, including the type of manure and how it is stored and applied.

Nitrogen loss from each facility during storage and application was estimated using guidelines⁷ developed by the University of Minnesota Extension and the Minnesota Department of Agriculture, or MDA. A 2014 survey of Minnesota’s 2014 corn crop⁸ was used to inform the prevalence of various manure application methods, with details provided in Porter and James (2020).³ Values for N loss used in this study are shown in Table 3. Annual N excretion amounts were reduced by the percent N loss during manure storage and handling, then subsequently reduced by the percent N loss during application.

Although the inorganic N in manure is available to crops immediately, the organic N portion acts as a slow-release fertilizer, becoming available to the crop throughout the growing season and up to several years following application.⁹ Nitrogen availability in this study was considered to be the sum of manure N available to the crop during the first, second and third years after application.⁷ Similar studies¹⁰ estimating the contribution of manure nutrients to meet crop N needs have also used the sum of three-year availability. Additionally, Sawyer and Mallarino (2008)⁹ suggest that 90 to 100 percent of swine manure N is available to the crop in the first year after application.

Some second-year N may be taken up by soybeans in a corn-soybean rotation, but it is assumed that all N used by soybeans is obtained entirely through N fixation. This assumption may lead to a modest overestimate of manure N application relative to crop needs, as research has generally indicated that if mineral nitrogen is present in the soil, the plant will use this nitrogen to support its growth and development.¹⁰

Using methods in this study and across all animal types, an estimated 26 percent of the manure N applied each year will become available during the second year following application (compared to 68 percent in year one and 6 percent in year three). Methods presented in this study would benefit from future accounting of the proportion of year two N availability that will be taken up by soybeans.

Many areas with high livestock densities are trending toward continuous corn rotations, however, which requires taking credits for second year manure nutrients. Additionally, a problem in temperate climates such as Minnesota is that mineralization of residual organic N may occur at times when crops are not present or are small, such as in the spring or fall, which can lead to increased leaching of manure N rather than uptake by growing crops.

In response, some states are recommending that fields reduce manure application rates to the point that total manure N applied is approximately equal to projected crop demand, particularly for those with a history of regular manure additions.¹¹

As-excreted amounts of phosphorus pentoxide, or P₂O_5, were multiplied by .44 to convert them to elemental P. The amount of manure P applied annually from each feedlot was assumed to be the same as that excreted, assuming that P loss is negligible for all but open-lots and lagoons.¹²

Purdue University suggests that 20 to 40 percent of P can be lost to runoff and leaching from an open lot, though much of this can be prevented using runoff collection systems. Additionally, 50 to 85 percent of lagoon P may settle to the bottom and be unavailable until agitated, at which point P in lagoon sludge can be applied to cropland.¹²

In contrast to potential N loss to the atmosphere, P loss from animal operations will directly enter the land environment, posing a risk to water resources through runoff or buildup of soil P over time.

Table 3: Nitrogen loss during manure storage and field application

Animal type	% N loss during manure storage	% N loss during manure application
Dairy	35%	15% if >= 300 AU, 30% if < 300 AU
Beef	35%	25% if >= 300 AU, 30% if < 300 AU
Swine	20%	15%
Poultry	35%	20%

^{Source: EWG via University of Minnesota Extension and Minnesota Department of Agriculture}

Estimating field nutrient needs

EWG obtained field boundaries with crop rotation history from the Agricultural Conservation Planning Framework, or ACPF, database¹³ and used them to estimate the average annual nutrient requirement for each field in the state. The ACPF toolbox provided six years of land cover history, from 2018 to 2024. EWG used the ACPF ManureMap Toolbox to identify fields where manure was likely to be applied, based on proximity to feedlots and crop nutrient needs. Using six years of crop history, nitrogen and phosphorus rates were determined using the toolbox.

Commercial fertilizer sales

EWG obtained county-level commercial fertilizer sales from the MDA 2018-2023 Crop Year Fertilizer Sales Reports.^{14,15,16,17,18}Fertilizer sales for each county were averaged for the five years to normalize sales figures for each county. Then average fertilizer sales for counties in each Minnesota BMP region¹⁹ were combined and reallocated based on the average N need determined by the ManureMap Toolbox.¹³

Manure allocation process

EWG modeled manure allocation from the point of production to neighboring agricultural fields, using the methods detailed in Porter and James (2020).³ Briefly, the program runs as a series of manure application loops, moving outward from each feedlot. Manure is applied based on the average annual N requirement of each field. As manure is applied to meet the N requirement of each field, P is also applied using the ratio of N to P that was individually calculated for each feedlot.

Each loop starts with a selection, for each feedlot provided, of the single nearest field, based on a straight-line distance measure, with an average annual N requirement greater than zero. A simulation of manure application subtracts the amount of N required by the field from the available N of the feedlot. Tracking accounts for the amounts of N and P applied during each loop of manure application. Once a field has met its total N requirement, it is no longer eligible to receive N from any feedlot. Once a feedlot has disposed of all its manure, it is removed from the analysis.

Results

Manure production

The methods described in this report show that Minnesota’s 23,503 active animal operations produce an estimated 48,991,052 tons of manure annually. For comparison to human population, Spellman and Whiting (2007)²¹ report an estimated 0.518 tons of waste generation per person per year, which puts the Minnesota animal-to-human waste equivalent at approximately 94.6 million people. That is over 16 times the 2024 estimate of Minnesota’s population, 5.79 million humans.

Contribution by size of operation

The manure generated on an annual basis is broken down by size of operation in the 2020 report and this report (see Table 4): small (fewer than 300 AU), medium (300 to 1,000 AU) and large (more than 1,000 AU). Operations larger than 1,000 AU account for only 4 percent of operations while producing nearly a third of the manure statewide. Although this is significant, operations between 300 and 1,000 AU account for nearly half of all manure produced statewide, which suggests that manure management for medium-size operations deserves additional focus.

Table 4: Percent of statewide manure production by operation size

Size of operation	Percent of all facilities	% of total manure	% of total manure
(2020 report, 150 lb finishing hog)	(2024 report, 150 lb finishing hog)
< 300 AU	78%	27%	24%
300 – 1,000 AU	18%	43%	43%
>= 1,000 AU	4%	30%	33%

^{Source: EWG via the MPCA and Midwest Plan Service}

Contribution by animal type

Table 5 lists the total allowable number of animals in Minnesota by animal type, along with the breakdown of facilities by dominant animal type and their percentage contribution to statewide manure N availability. In contrast to manure produced, N availability is the primary determinant of the amount of land area needed for manure application from each animal type.

Table 5: Percent of statewide applied manure nitrogen by animal type

Animal type	Number of animals	% of facilities	% of total applied manure N
(from MPCA registration)
Dairy cattle	1,321,621	17%	31%
Beef cattle	2,631,361	57%	32%
Swine	11,336,178	19%	28%
Poultry	58,949,312	3%	8%
Other	349,713	3%	.1%

Manure allocation

Nitrogen

Using the calculations described in this report, an estimated 404,095 tons of N are excreted annually by all animal feedlots in Minnesota. Nearly half of this N (172,734 tons) is considered lost to the atmosphere during manure storage and upon field application. What remains is an estimated 231,361 tons of manure N to be applied to cropland in Minnesota each year.

There is ample cropland in the state requiring N fertilizer, with 19,784,374 acres (281,756 fields) having an annual N requirement greater than zero, based on a six-year crop rotation, with a total annual N requirement of 836,304 tons. On a statewide scale, this suggests that manure can satisfy over 27 percent of the crop N requirement in any given year.

Results from the ManureMap Toolbox show manure application to 4,684,390 acres. Manure nutrients can fully satisfy crop fertilizer N needs on these acres.

Commercial fertilizer sales

Commercial fertilizer sales data may not accurately reflect fertilizer use in the county where it was sold. The MDA reports that clustering sales data from neighboring counties can reduce this geographical bias, and that statewide sales data is considered very accurate.

To account for this geographic bias, farm-use fertilizer sales for both N and P₂O₅ were summed within the state of Minnesota’s Agriculture Best Management Practice (BMP) regions,^{14,15,16,17,18}then redistributed back to counties based on each county’s respective share of N and P fertilizer requirement within that BMP region. P₂0₅ sales were multiplied by 0.44 to convert to elemental P.

Differences in soil parent material and climate have resulted in the development of a unique set of nitrogen BMPs for each region,¹⁹ which guided the assumption that fertilizer use will be similar for counties within each BMP region. The reallocation of fertilizer sales resulted in substantial differences between original and reallocated sales at a county level. (See Table 6.)

Table 6: High-risk counties for excess nitrogen from manure plus commercial fertilizer

Minnesota county	% Commercial fertilizer N	% manure N	% of total N Need
Cass	84.1	74.5	1.587182
Carlton	84.1	72.14	156.2
Morrison	84.1	69.9	154.0
Martin	89.4	61.2	150.7
Winona	100.9	49.6	150.6
Hubbard	84.1	61.4	145.5
Rock	77.6	66.2	143.9
Clearwater	126.8	15.9	142.7
Stearns	84.1	57.6	141.7

^{Source: EWG via the 2019-2023 MPCA fertilizer sales reports, MPCA, and Midwest Plan Service}

Although results suggest major N overapplication in some counties, the number of crop acres must also be considered. Percent N overapplication may be more pronounced in counties with less cropland, and absolute tons of N excess may be less than in counties with more cropland but a lower percentage of N overapplication.

Animal operations and manure pressure in vulnerable groundwater areas

Minnesota maintains a shapefile of “vulnerable groundwater areas”²⁰ where nitrate can more easily move through soil and into groundwater. There are over 100,000 fields within these vulnerable areas and the model output indicated that almost 33,000 received manure. The Central Sands and Southeast karst regions are especially concerning as those are the areas where we see concentrations of both manure feedlots and vulnerable groundwater areas.

A total of 6,480 facilities are located within the vulnerable groundwater area borders. Another 6,044 are within a mile of a border, meaning over half of the feedlots in Minnesota are within 1 mile of an area of vulnerability. For feedlots within 3 miles of vulnerable groundwater areas, the number grows to 18,355, or 78 percent of the feedlots. Figures 5 and 6 show the CAFO and medium-sized facilities within the vulnerable groundwater areas, along with the vulnerable groundwater areas themselves.

Figure 5. Large facilities by animal type within MPCA vulnerable ground water areas

Map of Minnesota showing primary animal types and vulnerable groundwater areas.

^{Source: EWG via MPCA}

Figure 6. Medium facilities by animal type within MPCA vulnerable ground water areas

Map of Minnesota showing primary animal types and vulnerable groundwater areas with color-coded dots.

^{Source: EWG via the MPCA}

Conclusion

As the animal agriculture industry grows, questions about the capacity of the landscape to uptake manure nutrients will become increasingly relevant.

At a minimum, state agencies should evaluate alternative management scenarios using a cumulative, spatial approach such as that presented in this report.

Additional focus should be placed on total fertilizer application from both commercial and manure sources in areas with high livestock density, which will require improved spatial information on fertilizer application at a sub-county level. Such analyses are necessary to allow for future adaption of livestock and cropping systems in Minnesota that may be necessary to address increasing water quality concerns.

References

¹ Minnesota Pollution Control Agency. Feedlots in Minnesota; St. Paul, Minnesota, 2019. Available Online from the Minnesota Geospatial Commons: https://gisdata.Minnesota.gov/dataset/env-feedlots.

²Office of the Revisor of Statutes, State of Minnesota. Minnesota Administrative Rules; Chapter 7020, Animal Feedlots; Minnesota, 2019. Available Online: https://www.revisor.Minnesota.gov/rules/7020/.

³Porter, S.A.; James, D.E. Using a Spatially Explicit Distribution Model to Assess the Contribution of Animal Agriculture to Minnesota’s Agricultural Nitrogen Budget. Agronomy. 2020, 10(4), 1–15.

⁴Lorimor, J.; Powers, W.; Sutton, A. Manure Characteristics; MWPS-18, Section 1; Midwest Plan Service: Ames, Iowa, 2004.

⁵ Wilson, M. Manure Characteristics. University of Minnesota Extension: St. Paul, Minnesota, 2018. Available Online: https://extension.uMinnesota.edu/manure-land-application/manure-characteristics.

⁶ Loubet, B.; Asman, W.A.H.; Theobald, M.R. Ammonia deposition near hot spots: processes, models and monitoring methods. Atmospheric Ammonia. 2009, 205–267.

⁷ Minnesota Department of Agriculture; University of Minnesota Extension. Nutrient and Manure Management Tables; St. Paul, Minnesota, 2012.

⁸ Minnesota Department of Agriculture. Commercial Nitrogen and Fertilizer Selection and Management Practices Associated with Minnesota’s 2014 Corn Crop: St. Paul, Minnesota, 2017

⁹ Sawyer, J.E.; Mallorino. Using Manure Nutrients for Crop Production; Iowa State University Extension: Ames, Iowa, 2016. Available Online: https://store.extension.iastate.edu/product/Using-Manure-Nutrients-for-Crop-Production

¹⁰ Andersen, D.S.; Pepple, L.M. A County-Level Assessment of Manure Nutrient Availability Relative to Crop Nutrient Capacity in Iowa: Spatial and Temporal Trends. Trans. of the ASABE. 2017, 60, 1669–1680.

¹¹Pettygrove, G.S.; Heinrich, A.L.; Crohn, D.M. Manure Nitrogen Mineralization. University of California Cooperative Extension: University of California, Davis, California, 2009. Available Online: http://manuremanagement.ucdavis.edu/files/134367.pdf.

¹² Sutton, A. L.; Jones, D.D.; Joern, B.C.; Huber, D.M. Animal manure as a plant nutrient resource. ID-101. Cooperative Extension Service, Purdue University, West Lafayette, Indiana. 1999

¹³ North Central Region Water Network. Agricultural Conservation Planning Framework. 2019. Available Online: https://acpf4watersheds.org/.

¹⁴ Minnesota Department of Agriculture. 2019 Crop Year Fertilizer Sales Report. St. Paul, Minnesota, 2019.

¹⁵ Minnesota Department of Agriculture. 2019 Crop Year Fertilizer Sales Report. St. Paul, Minnesota, 2020.

¹⁶ Minnesota Department of Agriculture. 2020 Crop Year Fertilizer Sales Report. St. Paul, Minnesota, 2021.

¹⁷ Minnesota Department of Agriculture. 2022 Crop Year Fertilizer Sales Report. St. Paul, Minnesota, 2023.

¹⁸ Minnesota Department of Agriculture. 2023 Crop Year Fertilizer Sales Report. St. Paul, Minnesota, 2024.

¹⁹ Lamb, J.; Randall, G.; Rehm, G.; Rosen, C. Best Management Practice for Nitrogen Use in Minnesota. University of Minnesota Extension: St. Paul, Minnesota, 2008.

²⁰ Minnesota Pollution Control Agency feedlot program Vulnerable Groundwater Areas Public View layer- 2025 https://services2.arcgis.com/7QMLozViUIV7KGFq/arcgis/rest/services/MPCA_Feedlot_Program_Vulnerable_Groundwater_Areas_Public_View/FeatureServer

²¹ Spellman, F.R.; Whiting, N.E. Environmental Management of Concentrated Animal Feeding Operations (CAFOs). CRC Press, 2007. 1–496

Topics

Learn about these issues

Midwest

In the Midwest, we’re working to make agriculture sustainable. The way farmland is used and managed has profound effects on our health, through the water we drink and the food we eat. But with simple changes, farming can actually be part of the solution.

Search

Key Issues

Women's Health

Food Chemicals