Journal of Nutrient Management – Quarter 1 - 2021

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Published by W.D. Hoard & Sons Co.

February | 2021

Journal of

Nutrient Management

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Worms do the dirty work Navigating manure analysis priorities Sorting out the solids



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Volume 2 | No. 1

Journal of


10 Worms do the dirty work

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Change on the horizon Organic matter is a measure of soil health Farmers need to lead the charge Packaging phosphorus for the future Steer clear of danger Navigating manure analysis priorities

20 22 26

Andy Dellava Jane Griswold

Sorting out the solids

Jenna Zilverberg

Training spreads out the benefits How do we find the true value of manure?

DEPARTMENTS First Thoughts . . . . . . . . . . . . 4 Policy Watch . . . . . . . . . . . . . 5 In the Field . . . . . . . . . . . . . . 6 Manure Minute . . . . . . . . . . . 13 On the Move . . . . . . . . . . . . 22 Fresh Paint . . . . . . . . . . . . . 24 Places to Be . . . . . . . . . . . . 25 Nutrient Insights . . . . . . . . . . 26

ON THE COVER Slow and steady, these alley scrapers push manure out of this southeastern Pennsylvania dairy barn where the Holstein herd is milked with automated milking systems. The manure solids are separated, dried, and reused as bedding in the freestalls. The farm’s remaining liquid manure is stored in a covered lagoon and then land applied onto crop fields. Photo by Andrea Haines, Union Bridge, Md.

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Journal of Nutrient Management (ISSN# 26902516) is published four times annually in February, May, August, and November by W.D. Hoard & Sons Company, 28 Milwaukee Ave. West, Fort Atkinson, Wisconsin 53538 Tel: (920) 563-5551. Email: info@ Website: Postmaster: Send address corrections to: Journal of Nutrient Management, PO Box 801, Fort Atkinson, Wisconsin 53538-0801. Tel: (920) 563-5551. Email: info@ Subscription Rates: Free and controlled circulation to qualified subscribers. For Subscriber Services contact: Journal of Nutrient Management, PO Box 801, Fort Atkinson, Wisconsin 53538, call (920) 563-5551, Copyright © 2021 W.D. Hoard & Sons Company. ALL RIGHTS RESERVED. Content may not be reproduced or used for any commercial activity without express written consent from W. D. Hoard & Sons Company.

February 2021 | Journal of Nutrient Management | 3


CHANGE ON THE HORIZON I Abby Bauer Managing Editor

t always feels strange to talk about heat abatement strategies for livestock during the winter when much of the country is dealing with weather that creates problems opposite of what heat stress does. However, if consideration is given to heat mitigation early enough, farms have time to make adjustments for the warmer months that will eventually return. Similarly, as I write this from our office in Wisconsin, a winter storm with snow, ice, wind, and bitterly cold temperatures is headed our way. And yet, global warming and climate change are on many people’s minds. Of course, these are not new concerns. Buzzwords such as greenhouse gases and methane emissions have been circulating for years, and scientists attribute the global warming trend seen since the mid-1900s to humans’ contribution to the greenhouse effect. While past attempts to put legislation into play to moderate climate change have been met with strong opposition, President Joe Biden has quickly pushed climate change mitigation to the forefront. The conversation has turned the corner from climate change to climate crisis, and the new administration has made it clear that legislation in this area is a top priority. In discussions about global greenhouse emissions, the finger often gets pointed at agriculture. At times, food production’s contribution to the problem may be overestimated, while other culprits seem to get a pass. Meanwhile, there are people all across the level of concern spectrum, from individuals who fear the worst about global warming to those who question its existence. Production agriculture is not optional; people around the world need food to eat. However, we can’t deny that cattle and crop production contribute to greenhouse emissions to some extent, and climate legislation is coming to agriculture, probably sooner rather than later. Now is not the time to sit back and see where the chips fall, if agriculture wants a say in what

this legislation looks like. That was the message that rang loud and clear during a panel discussion at the Sustainable Agriculture Summit held late last fall. The theme of that conversation was that farmers and others in agriculture need to lead this conversation; if not, the results will likely not be what we are hoping for. Read more about this discussion on page 8. Several panelists stated that climate change legislation must be economically beneficial for farmers; they also emphasized the need for it to be voluntary. There seems to be agreement on that front by at least some lawmakers. In a media call, Senator Debbie Stabenow, who is chair of the Senate Agriculture Committee, shared a few details about the proposed climate bill she is endorsing. “What we are talking about is a system that is voluntary and producer led,” Stabenow said. “The Growing Climate Solutions Act creates a producer advisory committee to USDA, which is very important.” To make sure climate legislation for agriculture is financially sustainable and voluntary, farmers need to be part of the planning process. Crop farmer Brandon Hunnicutt, who spoke during the panel discussion, said that we can either drive this train or be taken for a ride. With much at stake for not only this generation of farmers but also for generations to come, agriculture must find its seat at the table. In the end, I think we can all agree that change is coming, and the end goal is a future that has the same plentiful resources we enjoy today. Let’s embrace the opportunities that are before us, work through the good and the bad, take control of what we can, and make 2021 the best it can be. Until next time, Abby

Let us know your thoughts. Write Managing Editor Abby Bauer, 28 Milwaukee Ave. West, P.O. Box 801, Fort Atkinson, WI 53538; call: 920-563-5551; or email:

4 | Journal of Nutrient Management | February 2021


CALIFORNIA The California Department of Food and Agriculture (CDFA) awarded nearly $25.4 million in grants in 2020 to fund methane reduction projects across the state. The grants are part of the Dairy Digester Research and Development Program (DDRDP) and the Alternative Manure Management Program (AMMP). In all, 12 DDRDP projects totaling $16.5 million and 13 AMMP projects totaling $8.9 million are being funded. These projects will reduce an estimated 191,360 metric tons of greenhouse gases per year. They will also contribute $32 million in matching funds. Since 2015, 235 dairy families in California have participated in methane reduction efforts through these programs. In all, these projects eliminate the release of 2.3 million metric tons of greenhouse gases annually, which is the equivalent of removing more than 495,000 cars from the road.



The Innovation Center for U.S. Dairy announced a memorandum of understanding with the U.S. Environmental Protection Agency (EPA), which formalized a relationship that began in 2012. The memorandum opens doors for further collaboration in areas of mutual interest and allows the agency to gain a deeper understanding of and support for U.S. dairy farmers. “The MOU will explore mutually beneficial opportunities for dairy farms of all sizes, geographies, and practices to gain benefits from EPA resources, including research grants, educational training materials, and data,” said Innovation Center for U.S. Dairy President Barb O’Brien.

Four groups have joined together to advocate for productive changes that will protect water sources while supporting farmers. The groups are Clean Wisconsin, the Dairy Business Association, The Nature Conservancy in Wisconsin, and the Wisconsin Land and Water Conservation Association. The partners have four principles that will guide their efforts: 1. Ensuring clean drinking water. 2. Reimagining the CAFO program. 3. Supporting current conservation efforts and fostering innovation. 4. Improving the state’s non-point pollution from agricultural sources program.

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CALIFORNIA OREGON The Oregon Water Resources Commission voted unanimously to deny a request by Stand Up to Factory Farms, a coalition of environmental groups and others. Their petition asked for the establishment of a 5,000-gallon daily limit on water withdrawals by new or expanded Concentrated Animal Feeding Operations (CAFOs) in Umatilla and Morrow counties. Under the state’s livestock watering exemption, water can be diverted or pumped for livestock use without a water rights permit from the Oregon Water Resources Department, which the commission oversees. Members of the commission felt a petition was a not a good way to handle this problem and looks to coordinate with other state agencies that oversee CAFOs.

People living in Southern California can now pay a premium to receive some of their natural gas as biofuel generated from landfills and cow manure. California state regulators agreed to a three-year plan by Southern California Gas and San Diego Gas and Electric to sell what the utility considers renewable natural gas created from capturing methane from manure lagoons at dairy farms, landfills, or other places. Customers can pay a higher rate to have this biofuel blended into the natural gas piped into their homes and businesses. According to an article in Bloomberg, environmental groups are opposed to this idea, citing that it’s an effort by the utility companies to distract from the push to phase out natural gas in California. Their stance is that biogas does little to cut emissions or address the industrial impacts of dairy farming.

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February 2021 | Journal of Nutrient Management | 5


Cover crops and manure application are two ways to build soil organic matter.

ORGANIC MATTER IS A MEASURE OF SOIL HEALTH Soil organic matter metrics and emerging research can help farmers better manage their farm fields. by Amber Radatz, Matt Ruark, and Erica Gentry


oil health has become a common part of the discussion for cropping and nutrient management systems. While soil health is more conceptual, soil organic matter often enters the conversation as a way to measure progress toward soil health benefits. However, the two aren’t necessarily interchangeable. For farms engaging in soil health practices and discussions, it is valuable to understand the intricacies of soil organic matter and the way it will be used in the future for farm and environmental management. The science of soil health and soil organic matter is in its infancy. By providing a summary of

the state of the science, we hope it will help bring context as you come across new results.

What is soil organic matter? Soil organic matter (SOM) is a key component of both soil health and soil fertility, and there is renewed interest in building SOM for improved soil function. SOM (or soil organic carbon, which compromises the majority of total SOM) is included in nearly all lists of soil health metrics. For example, the Cornell Assessment of Soil Health includes SOM (via loss on ignition) as part of the basic package. Historically, nearly all farmers have at least one measurement

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of SOM on their fields as it is included in most standard routine soil fertility packages offered by soil test labs. Soil organic matter (ranging from 1% to 5% in most soils) is comprised of dead plants and organisms, as well as animal wastes, in various stages of decay. The majority of SOM exists in a stabilized form, historically referred to as humus. This highly stable material is the carbon that is bound to clay particles or found inside of soil aggregates. Soil aggregates are stable pieces of soil that are a mix of silt, clay, organic material, soil bacteria, and fungal hyphae. Some SOM exists on the outer edges of aggregates or outside the aggregate completely. This part of the organic matter is referred to as the active pool, which “turns over” during a single growing season. In other words, it’s the pool of organic matter from which plant-available nutrients are released. The active pool of SOM consists of permanganate oxidizable carbon (POXC) and mineralizable carbon (min-C). POXC can be measured by

What is the value? There are multiple potential benefits to boosting SOM. Two popular reasons are to elevate yield potential of the soil and supply nutrients to crops. A recent global analysis revealed that both corn and wheat yields rose with increases of SOM (in the upper 6 inches) up to 4%. For a more regional analysis, studies from Wisconsin and Minnesota Discovery Farms revealed similar trends using data from 218 farm fields (see figure). While there are certainly a lot of other factors to consider in order to improve corn yield, there appears to be evidence at both the global and regional level that there is agronomic value to building SOM. Using measures of SOM, especially total SOM, to guide nitrogen fertilizer recommendations can be complicated, and the strategies vary by state. There is evidence that POXC and min-C can be valuable measurements to guide decisions. Research at several universities across the country is being done to untangle the connection between these carbon measures and nitrogen rates to predict the degree to which a site will be

A cover crop of rye grows in the spring.

Soil organic matter organized by soil type Discovery Farms data from 218 sites 7 6 Organic matter (%)

a lab analysis that uses chemicals to oxidize carbon into CO2. Lab tests for min-C measure the amount of carbon consumed by soil microorganisms in a short period of time. Both POXC and min-C are popular biological soil health indictors that allow us to track progress in achieving soil health goals. They also help us to better guide nutrient management decisions on a shorter term basis than relying on total SOM measures alone.

5 4 3 2

Soil organic matter contains dead plants and organisms and animal wastes in various stages of decay.

1 0


Silt loam

Clay loam

responsive to nitrogen. Ultimately, the results will be used to develop regional recommendations for using these soil tests in nutrient management planning.

How can we build it? There are two key factors in building soil organic matter: adding more carbon into soil and protecting carbon after it’s applied. Improving carbon input into soil can come from crop residues, animal manures, and cover crops. This has been a very active area of research for several decades. Crop residues have been widely shown to be an important driver of SOM. Cropping systems with greater biomass returned to the soil, such as continuous corn rotations and rotations with alfalfa, build SOM. Manure additions to soil have been proven to elevate SOM over time compared to just N fertilization alone. General trends in long-term cover crop research show that increases in organic matter can be obtained with long-term cover crop use. Bigger gains in SOM can be realized when more cover crop biomass is grown and for more consecutive seasons. Protection of SOM comes with a

reduction in tillage. Reducing or eliminating tillage helps allow soil aggregates to form and stabilize, protecting the carbon that was added to the soil. Tillage breaks up soil aggregates and enhances the oxidation rate of residues. Allowing this process to happen without soil disturbance lets stable aggregates form, thus securing more carbon in the soil. Increasing carbon inputs with manure or cover cropping is very system specific. Factors like soil texture, weather, crop rotations, and history of tillage and manure all play important roles. Wisconsin and Minnesota data show that soil texture is a driving factor, as soils with higher clay content are able to store more carbon than sandier soils. Collectively, building soil organic matter (as well as active carbon pools and soil health) is a long-term game. But there is an abundance of evidence that improving SOM is both possible and advantageous for productivity. We certainly don’t want to suggest building SOM will be easy — incorporating manure, cover crops, and reduced or no-tillage into cropping systems come with challenges. Ultimately, though, it is a worthwhile endeavor. ■ The authors are with the University of Wisconsin-Madison Division of Extension’s Discovery Farms program.

February 2021 | Journal of Nutrient Management | 7

Farmers need to lead the charge The most effective climate change legislation would be driven by those within agriculture. by Abby Bauer, Managing Editor

s the new administration settles into the White House, it’s clear that climate and the environment are high on their list of priorities. While not everyone agrees on the seriousness of climate change, the cause, or its impact on the future, it is a concern of many that is not going to just go away. In fact, many conversations have shifted from the verbiage of climate change to climate crisis, and legislation that affects agricultural producers will inevitably become a reality. Just two weeks after the election took place, Jamie Powers, the senior manager for agricultural engagements with the nonprofit program Rural Investment to Protect our Environment (RIPE), moderated a panel discussion during the Sustainable Agriculture Summit. The conversation focused on what would make climate legislation successful.

Voluntary and viable “Regardless of the election results, many agricultural producers sense that climate legislation is headed their way,” Powers said. “What role should agriculture play in climate solutions?” The first comments from the panel came from Eunice Biel, who owns a dairy and crop farm with her husband, her son, and his family in southeastern Minnesota. Biel said they have used many conservation practices over the years. “Farmers and ranchers understand

the importance of conserving natural resources and mitigating climate change. Their livelihoods depend on it,” she said. However, she indicated that these practices often require significant time, money, and expertise. “That’s why programs that provide financial and technical assistance for conservation efforts are so vital, and so popular,” she said in reference to the Natural Resources Conservation Service (NRCS) within USDA. Marty Matlock, a professor of ecological engineering at the University of Arkansas, also gave a nod to USDA’s conservation programs. “We have 2.3 billion acres of land in the contiguous U.S. Of that, over 900 million acres are in private farm ownership. If we are going to achieve any sort of continent-scale improvement in conservation, we are going to have to engage private landowners in a way that is viable,” he stated. “That’s why USDA’s implementation of compliance through voluntary engagement is so powerful, and it has been working.” He used soil erosion as an example. “Soil erosion has been declining dramatically for the last 40 years in row-crop areas. We are not done yet; we still have too much erosion. Every farm knows erosion is bad,” he said. “But reducing it is a possibility when we start engaging conservation programs and expanding our partnerships.” Matlock has been working with ag

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communities around the nation for 20 years to identify opportunities for improving land conservation, production efficiency, and farm profitability. “You have to have all of those things if you are going to have a sustainable agricultural enterprise,” he said. He emphasized farmers’ important role in protecting our natural resources and compensating them for that work. “We need to pay our farmers for what they give us,” he said. “It’s a simple, simple principle.”

It became political Despite the growing need for climate change legislation, establishing forward progress has been very difficult for lawmakers. Clare Sierawski, who worked for a number of years as a legislative aide on a variety of governmental efforts in climate change and agricultural policy, shared her insight on this topic. “There are a number of reasons why previous attempts to pass climate legislation have failed,” she said. “The first and biggest is that climate change has become a truly divisive, partisan issue.” She said some elected officials won’t even bring the topic up in conversation because they think their constituents will oppose it. “In a country as deeply divided as ours is between Republicans and Democrats, you need people from both parties to push for legislation or nothing is going to

happen,” she shared.” She believes the second barrier to climate legislation has to do with the cost. “We’ve all been convinced that climate legislation is going to come at a big cost,” she explained. “While transitioning away from fossil fuels will come at a cost in the near term for some, it can also create serious economic opportunities, and the cost of inaction most certainly will outweigh the cost of action.” To overcome these barriers and move forward, Sierawski said, “We need to change the players and reframe the approach.” She feels it will take a commitment from farmers to get this done. “We need ag producers to take the reins and make ag climate legislation work for them. We need legislation that is led by middle America. We need legislation that will create real benefits; benefits worth fighting for by farmers and ranchers,” she stated. “There haven’t been any attempts to

date to design climate legislation that puts the agriculture community front and center. That’s the missing piece,” she emphasized.

Farmers at the helm Nebraska crop farmer Brandon Hunnicutt agreed with Sierawski’s comments. He farms with his family at Hunnicutt Farms where they grow corn, soybeans, and popcorn, using various methods and technology to reduce inputs and protect soil, water, and air quality. “We need to lead this charge. It’s an opportunity that comes around maybe once in a generation,” he shared. “All the stars have aligned at this moment in time for us to push for the legislation to not only help farmers but help the climate crisis we are in.” Hunnicutt said farmers have opportunities for government payments, but those that center on climate change have been missed. He feels there is a

need to compensate farmers who are already using climate-friendly practices along with incentivizing more farms to do so in the future. The first challenge for farmers to enact change, Sierawski said, is collaboration. “You need the ag community to agree that it’s going to fight for it,” she said. Farmers across the country are in different situations and face their own unique challenges. However, future policies could impact all farmers, and climate legislation designed with farmer input would be better than legislation that has little ag input at all. Hunnicutt encouraged his fellow farmers to step up to the plate. “As farmers, we need to take the lead. We need to be the ones who are driving this conversation. It’s coming,” Hunnicutt said. “It’s either coming at us, or we are going to drive the train and make sure we get the legislation we want and need.” ■




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Dairy Farmers of Washington

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A Washington dairy turns manure into compost and usable water with the help of some little underground creatures. by Abby Bauer, Managing Editor


hen looking for a way to reduce the amount of wastewater being trucked from his central Washington dairy, Austin Allred came upon a fairly simple solution: a worm-powered water treatment system. Growing up on his family’s potato farm near Royal City, Wash., Allred worked on a local dairy during high school. In 2009, Allred and his dad, Jerry, partnered with the owners of that farm, Royal Dairy, and then purchased the farm from them in 2016. Today, Royal Dairy is home to 6,000 milking cows, a herd of mostly Jerseys. Freestall barns house about 60% of the herd, while the rest of the milking cows, dry cows, and heifers are kept on open lots. The farm was designed so that all of the flush water from the freestall barns and vacuumed manure from the drylots ended up in a large storage basin, which would flow into an even larger settling lagoon. Allred said a pipeline system was in place for irrigation, but the water from the lagoon was too dirty to use effectively, causing the sprinklers to plug up often. They also didn’t have enough acres available to use all of the water through irrigation. That meant the dairy was trucking millions of gallons of wastewater or “green water” out of the lagoon each year. Depending on nutrient test results, it would take an average of 4,000 acres to dispose of properly, and most of those acres were a distance from the dairy, Allred said. Also, most of the water used to flush the freestall barns came out of the lagoon as well. Flushing with this dirty water had a negative impact on herd health and milk quality. Just a year after he purchased the dairy, Allred identified the need to do something different.

pilot project in 2017 that handled just 10,000 gallons of wastewater daily. Allred said he played around with that biofilter for a year and then installed a much larger system that could utilize more of the dairy’s water per day. The exception was the flush water, which was still coming out of their green water storage. Happy with the results, in 2020 he finalized the system, which can now handle 750,000 gallons of green water per day, most of which is recycled and reused multiple times.

Where the worms live

Today, the dairy’s manure first goes through solid separation. The separated solids are composted and then land applied or used as bedding. The green water is destined for the BIDA System, which is located on a 10-acre footprint next to the farm’s manure

A huge liability “Any dairy farmer that trucks green water can relate to where I was at,” he said in a presentation during the virtual Sustainable Agriculture Summit. “Having multiple trucks hauling water 5 or 6 months a year was not fun, and the liability connected to that is huge.” Allred considered manure storage to be the biggest liability on the dairy, and that was a major consideration as he looked for a solution to meet his nutrient management needs. He found the answer to his problem while attending World Ag Expo in Tulare, Calif. It was there where he first talked with BioFiltro, a wastewater filtration company, about their Biodynamic Aerobic (BIDA) System, which uses worms within a passive aerobic system to clean wastewater. With some initial skepticism, he started out by installing a

February 2021 | Journal of Nutrient Management | 11

Austin Allred, who operates a 6,000 cow dairy in central Washington, recycles water using an aerobic filtration system.

Dairy Farmers of Washington

lagoons. It travels through a pipeline by gravity or with pump assistance when needed. The wastewater is irrigated across the top of the concrete containment basins that are 5 feet deep. Each basin has drainage cells along the floor, a 1.5-foot layer of crushed rock, and a layer of wood chips on top. It is within this wood chip layer that the dirty work takes place, and worms are key to getting the job done. As the worms burrow through the shavings, they make channels that help evenly distribute nutrients and water throughout the system. Their guts are rich in the microbes needed to remove the contaminants in the water they digest. Each worm excretes 10 pounds of castings each year, which maintains the microbial activity of the system. The waste, or vermicastings, are also a highly beneficial soil amendment that is sought after as a fertilizer. Every year and a half, the shavings layer and vermicastings from Royal Dairy’s system are removed and sold to nurseries. An estimated 4.5 cubic yards of castings are generated per cow per year. It takes just four hours from when the water enters the system for it to seep through the worms and microbe media

and then head out of the containment basins through exit pipes as an irrigatable tea water that can also be used to flush the barns. The ability to clean the water so quickly also reduces odors that develop when manure and wastewater sit untreated in a lagoon. Allred said the system runs effectively all year long, with just a few changes needed when it is really cold out to assure the water pipes don’t freeze. As for the worms, Allred said they are very self-sufficient. They simply need to be fed with the green water. Each worm has a lifespan of about six years, and Allred noted that the worms reproduce very fast, so each worm may add 400 to 600 worms to the workforce each year. The only time new worms need to be added is when the shavings and vermicompost layer is removed and replaced.

Successful results

Royal Dairy is one of just a handful of farms currently using this biofilter system. Since it began operating, Allred has achieved an 89% lifetime removal average of total suspended solids, total nitrogen, total volatile solids, and total phosphorus. Further value may come in the form of selling carbon credits, which the farm recently became verified to do.

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Allred has deemed two main benefits of using the BIDA system. The first is that they are able to flush their barns with the cleaner tea water, not green water like they used to. “This has been a big win for health of the animals and it improved our somatic cell count,” Allred said. The second is that the dairy does not have to use trucks to haul away nearly as much green water. “That has been a huge victory,” said Allred. The biofilter is also successful at removing 90% of the methane produced by manure. An uncovered lagoon can create 7 to 9 tons of methane per cow per year; through vermifiltration, the amount of methane per cow can be brought down to just 1 ton annually. “I think as a farmer, good environmental stewardship is innately important to all of us,” said Allred. “We do the best we can, make improvements, and make sure we can always graduate to the next level of sustainability.” For Royal Dairy, worms were the secret ingredient to turn their green water into cleaner water that can be used in several ways. With less methane being released and fewer trucks on the road, the environmental benefits go beyond the dairy’s borders, too. ■


WHEN ARE POULTRY LITTER NUTRIENTS AVAILABLE? As for crop availability, the authors explained that N is primarily in the organic form in poultry litter, up to 80%. Organic N needs to mineralize before becoming available to crops. Studies have shown that approximately 45% to 55% of the total N becomes available to the plant the first year of application. Reduction of N availability may occur when the litter is aged or has gone through some level of composting. Ammonium volatilization is usually higher on warm, windy days, but incorporation can reduce this loss and potential runoff losses. On the flip side, a large fraction of manure P is available immediately after application, between 50% and 100%. Similarly, nearly 100% of K is



nlike commercial fertilizers that can be mixed to achieve a desired nutrient content, manure comes with fixed nutrient ratios. These ratios often don’t align perfectly with the needs of field, and this can lead to over or under application of certain nutrients, including nitrogen and phosphorus. In a University of Minnesota Extension Crop News article, extension educator Chryseis Modderman posed the question, “Should you apply manure based on nitrogen needs or phosphorus needs?” The answer, she wrote, depends on the soil and the manure test results. If a field is already high in phosphorus, a farmer may decide to apply manure on a phosphorus-based rate to avoid further build up. If phosphorus levels are low, a nitrogen-based rate would work well as long as it won’t elevate phosphorus levels too high. Even though phosphorus is less mobile than nitrogen, Modderman explained there is still a risk of loss through runoff and erosion. To avoid phosphorus build up, she shared two strategies. One is to apply the nutrient at a phosphorus-based rate. An alternative method is to apply manure at the nitrogen-based rate, but then not apply any more manure to that field until the excess phosphorus has been utilized.

available with proper application. Moisture content and nutrient concentration can be highly variable, depending on production conditions, storage, and handling methods. The authors reminded farmers that laboratory analysis is the best way to determine the level of nutrients in the litter. Litter analysis (lb./ton)


oultry litter can serve as a significant source of crop nutrients for states near large poultry producing areas. Peter Tomlinson and Dorivar Ruiz Diaz of Kansas State Research and Extension shared details about litter content and how it can be used in a K-State Agronomy eUpdate newsletter. Their analysis of 213 poultry manure samples showed the variation that exists in poultry litter. While the average pounds of nitrogen (N) per ton of litter was 56, there was a range of 12 to 92 pounds per ton. The spread was even greater for phosphorus (P), which averaged 53 pounds per ton but varied from 7 to 165 pounds. Potassium (K) samples fell between 6 and 72 pounds per ton, with 46 pounds as the average.

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February 2021 | Journal of Nutrient Management | 13

Packaging phosphorus for the future Recent developments in the manure phosphorus extraction (MAPHEX) system bring it one step closer to on-farm use. by Clinton Church


airy and swine manure is typically in slurry form and contains nutrients and organic material that are beneficial to crops. Unfortunately, the concentration of nutrients in dairy manure is too low to make transportation of bulk manure over large distances economically viable. For this reason, dairy manure tends to be applied to fields near where it is generated, and over time, soil phosphorus (P) concentrations often become in excess of crop demands. Furthermore, because P runoff from agricultural operations plays an important part in eutrophication and removal of oxygen from water in streams and other water bodies, farmers face mounting pressure and regulation to not apply manure to those soils. A manure phosphorus extraction system, named the MAPHEX System, was jointly developed by USDA-ARS and Penn State University. It was designed to be a solution for the P overloading that happens when unnecessary P is added to agricultural soils. It is scalable such that it can be used as a mobile system, and it has shown high versatility in treating dairy manure from farms that vary widely in herd size, bedding type used, and methods of manure treatment and handling. The system is capable of removing greater than 90% of the P from dairy manure but at a cost of about 6.25 cents

The MAPHREX System uses a four-step process to remove nearly all of the phosphorus from a wide range of manure types. per gallon. Cost is clearly a roadblock to widespread adoption of the MAPHEX System, so a major part of our recent efforts has been to reduce these costs.

How it works The full system, as used to treat dairy manure (see figure), has four stages: Stage A — Liquid/solid separation is done using an auger or screw press to remove solids larger than 1 mm. Stage B — Liquid/solid separation takes place using a decanter centrifuge to remove solids larger than about 30 micrometers (µm). Stage C — This stage involves chemi-

14 | Journal of Nutrient Management | February 2021

cal treatment, typically ferric sulfate. Stage D — Final liquid/fine solid separation occurs using an AutoVac filtration unit with diatomaceous earth (DE) as a filtrate material.

Cutting the costs By combining the following three measures, we have demonstrated significantly lower treatment costs of just less than 1 cent per gallon of manure treated: 1. Using lower cost chemicals as alternatives to ferric sulfate. A series of experiments were conducted to show that the MAPHEX System could use many different chemical

ments to remove phosphorus from dairy manure. In all cases, greater than 90% P removal efficiency was achievable. 2. A method for the diatomaceous earth to be regenerated and reused. We employed an ashing procedure to recover the DE for re-use as filtration media on the AutoVac. We found that DE could be reused up to three times by simple ashing without appreciable reduction in flow rate. We further found that once the flow rate fell to 75% of the original flow rate, the DE could be regenerated to an original flow rate with simple acid washing. 3. An alternative for the final separation step. We found that if the effluent from the decanter centrifuge, which operates at about 2,500 times gravity, was directed to a disc-stack centrifuge, which operates at about 12,000 times gravity, the resulting effluent was 75% P-free compared to the original raw manure. This is a sufficient P reduction level for most farms. Furthermore, directing the fluid reject from the disc stack centrifuge to the AutoVac resulted in a stackable solid.

Benefits beyond dairy Would the system also work on swine operations? A pilotscale study showed that the MAPHEX System can remove greater than 96% of the phosphorus in swine manures. It strongly suggests that, once scaled up, the essentially P-free effluent could be beneficially used for fertigation (the injection of fertilizers, soil and water, amendments, and other products into an irrigation system) without further loading the receiving soils with P. This scaling up has the potential to reduce storage volumes to mitigate overflow problems during large storms. Furthermore, this study suggests that capital equipment costs for swine manure could be as low as $150,000. Treatment costs would range from 0.9 to 3.6 cents per gallon without DE regeneration, and it could be as low as 0.4 to 1.44 cents per gallon with DE regeneration.

Uses for manure fractions The MAPHEX System is capable of removing greater than 95% of the phosphorus from a wide range of manure types while retaining greater than 90% of N in the effluent for the beneficial use by the farmer. This resulting effluent could be immediately used for fertigation, as most of the negative aspects of raw manure (including P and solids content) have been reduced. Since most of the solids (and all solids greater than 1 µm) are removed, the effluent from the system could be applied as irrigation through a sprinkler system. The solids removed by the stages of the MAPHEX System also have beneficial uses. Bulk solids (typically about 80% of total solids) removed by the screw press have been shown to contain relatively low amounts of P (9% to 17% of total P) and are often valuable for farmers to use as composted bedding material. The AutoVac solids (about 10% of total manure solids) contain considerably higher amounts of P (40% to 50% of total P) and are combined with the DE filtrate material. The best use for them is to be ashed in order to regenerate and reuse the DE. The centrifuge solids also comprise about 10% of total solids and contain higher amounts of P (40% to 50% of total P). These high-P solids also have multiple potential end users.

Manure Slurry A. Auger Press


B. Centrifuge

Liquids Bulk Solids Chemical Treatment

Medium sized solids C. Chemical Treatment Tank Liquids D. AutoVac Filtration Unit

Treated effluent Fine solids and diatomaceous earth

For dairy farmers, concentrating manure P into a more compact form cuts their fuel costs considerably, allowing them to economically transport P to fields farther from the dairy that need it. This allows the much greater volume of liquid effluent to be applied to fields close to the dairy that, over the course of time, have come to have higher levels of P but still need N. This option does not remove P from the watershed, but it does result in improved P allocation for crop use. Reports from dairies that have an operating centrifuge indicate that the centrifuge solids are a highly sought-after commodity by nurseries and mushroom farmers. Local organic farmers may find the composted solids from the centrifuge to be an ideal organic soil amendment as well. The composted and bagged centrifuge solids can also be sold in garden centers, the same way composted manure is. The solids could also be useful for energy generation. Once centrifuge solids are dried to about 30% moisture, they make an ideal feedstock material. This option also concentrates the phosphorus into a very dense form (residual ash) that can serve as a compact form of phosphorus and trace element fertilizer. A simplified unit that could handle 125,000 gallons per day and remove 50% to 60% of P from manure is currently in the engineering phase. The future goal is to obtain license patents for these two systems so they can be built commercially and be available for farms to use. ■

The author is a chemist with the USDA Agricultural Research Service’s Pasture Systems and Watershed Management Research Unit, University Park, Pa.

February 2021 | Journal of Nutrient Management | 15

A fence provides a physical barrier to keep people from falling into a manure lagoon.

Steer clear of danger Follow these five tips to help keep you and your crew safe during manure application and handling. by Liz Matzke fter a busy fall of harvest comes another manure application season. It is also the time of year when there is an uptick in accidents and deaths related to manure storage. From 1960 to 2016, there were over 150 deaths from manure storage gas exposure, with half of these accidents occurring on dairy farms. Unfortunately, one in five of these incidents involved the death of a second person who was trying to provide help. Amy Schmidt, an associate professor of biological systems engineering and animal sciences at the University of Nebraska-Lincoln, outlined five tips for a safe and successful manure application process in a University of Nebraska Extension dairy webinar. 1. Fence in manure storage areas. “I have been to a number of farms where the manure pit is very much

exposed,” described Schmidt. Exposed lagoons can make it easy for people to accidentally fall or drive into them. Fences and guardrails help to give a lay of the land, especially during dusk and dawn, when the sunlight makes it difficult to see. It also provides a physical barrier for distracted drivers. Always have a fence around your manure storage. Numerous lagoons have liners, which make climbing out after falling in nearly impossible. By having a fence and posting visual warnings, these accidents can be prevented. 2. Recognize the risks of hydrogen sulfide. The single biggest concern to manure application is deadly gases, and chief among them is hydrogen sulfide (H2S). “You really have no idea if the concentration of hydrogen sulfide is deadly unless you are measuring it,” said Schmidt.

16 | Journal of Nutrient Management | February 2021

At its lowest concentration, H2S smells like rotten eggs. With a concentration of 5 parts per million (ppm), symptoms include nausea, tears, and headache. When you double that concentration, someone can experience fatigue, headache, irritability, and dizziness. Once levels reach 50 to 60 ppm, coughing and eye and throat irritation become problematic. Over 100 ppm, a person will have eye and respiratory tract irritation including fluid in the lungs. When levels reach 300 to 500 ppm, victims will stagger, collapse, and can die within 30 minutes. Once over this threshold, death can occur even more quickly. “We tend to think that gases are only an issue in confined spaces with limited ventilation,” explained Schmidt, but that is hardly the case. Weather can play a factor as well, and she shared one example of this. “There was fog near the ground and the gas was released while the pit was agitating. Since hydrogen sulfide is heavier than air, the gas concentrated around the area, killing the farmer and 16 animals.” Schmidt encouraged farmers to invest in personal protection equipment, like a H2S monitor and a ventilator. She also

advised, “At minimum, make sure you have someone else outside of the manure storage area who can pull you out if there is trouble. You want to have a harness or rope so they can get you out of the area quickly without them entering.” 3. Conduct proper training. Training everyone on your farm to recognize the signs of gas exposure and how to get help can be lifesaving. Key signs for gas exposure include a sense of being hot and clammy, loss of motor skills, fast heartbeat, tightness in the chest, panting, nausea, vomiting, and anxiety. “If you are feeling this way, you need to get out of the area as soon as possible and into the fresh air. Schmidt explained, “There might have already been damage, but if you get outside, someone is more likely to find you and get you help.” But recognizing the symptoms is only half the equation. Employees also need to know how to get help. It is important that everyone knows the farm address to tell emergency responders and can accurately describe the location on the farm. Finally, it is important to stress that no one enter the manure storage to attempt a rescue; wait for help to arrive. 4. Recognize the potential for methane pockets. In swine manure systems, there are usually slotted floors with manure storage underneath, leading to limited oxygen content. Anerobic microbes break down carbon in these pits and create methane foam. Methane is highly flammable and can asphyxiate someone at a concentration of 50% or above. “It’s important to inspect storages for foam regularly; it can pop up overnight,” stated Schmidt. Agitation of the pit can help break down the foam, but it needs to be done with caution, and make sure the equipment does not create sparks. 5. Heed equipment warning signs. We have all seen the warning stickers posted on tractors and equipment. While we may glance over them, they provide an important reminder. Tractor power takeoffs (PTOs), guard shields, and deadman switches are in place for our protection. In less populated areas, it may take longer for emergency personnel to arrive, and rescue services may not be as sophisticated. It is equally important to make sure employees understand how to use equipment and are assured they will receive help if they ask for it. Often,

employees are hesitant to ask for help out of fear of being fired or taking up even more time during an already busy day. But long hours and time crunches lead to accidents; an estimated 80% of these accidents are a result of carelessness. “It is important to stop and think,” Schmidt emphasized. These five tips can be lifesaving on the farm during the fall and spring manure

application seasons, and every life counts. “If sharing these tips can prevent injuries or deaths, then I am hopeful that message is received,” said Schmidt. ■

The author is a freelance writer from Monroe, Wis. She owns Denim Works LLC.

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Navigating manure analysis priorities Look at a manure analysis report piece by piece to get the most from the results. by Scott Fleming

t times, interpreting manure analysis reports may seem to practically require a doctorate degree. Confusing is just the tip of the iceberg of obstacles one might face when navigating through the ocean of information. As a Certified Crop Advisor (CCA), I have seen numerous reports from various laboratories, and even I may become disoriented when reading a manure analysis. Much of this confusion stems from the diverse report formats across laboratories. Terminology also challenges the reader as it differs across reports, even though it discloses the same information. One valuable approach for interpreting a manure analysis report is to break it down into individual components. When we look at each part of the report on its own, the whole becomes a lot more manageable.

The most important analytes All manure reports will include the following basic analytes in some format. Depending on the analysis package, additional elements may be included. Typical add-ons are micronutrients such as manganese, zinc, and boron. Moisture: This component determines how manure will be handled and how it will behave in the environment. It also dictates if results will be given in nutrients per ton or nutrients per 1,000 gallons. Nitrogen (N): This nutrient is a key contributor to plant growth, and it is especially important early in the growing season. Nitrogen content can

This sample manure analysis report shows just a portion of the data that can be used by farmers to make cropping decisions. be difficult to determine because it is expressed in many ways. Manure also contains multiple forms of nitrogen such as organic, inorganic, and total Kjeldahl nitrogen (TKN). The number to focus on is total nitrogen, remembering that not all nitrogen is available the first year it is applied. The nitrogen content of manure will also vary by application method. Manure that is injected, incorporated, or surface applied will have different forms of nitrogen available for the crop. This is due to volatilization that takes place when the nitrogen sits on the soil surface. Phosphorus (P): The phosphorus within the proverbial “NPK” group provides energy for the plant by aiding in photosynthesis. Phosphorus also plays a key role in root development and reproduction. Potassium (K): This element assists water movement in the plant and helps

18 | Journal of Nutrient Management | February 2021

create strong stalks and stems. Sulfur (S): This is often the forgotten nutrient. Sulfur almost made the list of primary macronutrients when they were first discovered. Sulfur aids in nodule development, nitrogen fixation, and improved winter hardiness in legumes. It is also believed to play a role in nutrient density.

Prioritize the nutrients Nutrients are applied to crops for different reasons. If the goal is to meet a grass crop’s needs, nitrogen is the most important analyte in a manure analysis. Depending on manure application rules, the manure can then be applied at a rate to meet the nitrogen demand. When applying manure as a nitrogen source to a grass crop, you should also review the sulfur content of the manure. While sulfur additions were not necessary several decades ago, it is now a vital nutrient addition due to

reduced atmospheric deposition. While the manure is not applied to meet the crop’s sulfur demand, the sulfur in the manure should still be credited against the crop’s sulfur demand. Applying manure based on a phosphorus management strategy is becoming more prevalent — as opposed to doing so in order to meet crop demands. The phosphorus management methods vary from state to state, but they all rely on knowing crop removal and applying the same or less than crop removal. Another strategy for manure application is to look at the analysis and determine where that manure would fit best within the system. For instance, if the manure contains high volumes of nitrogen but low volumes of phosphorus, it would fit well on a grass crop. If the manure is low in nitrogen, it may be a good fit for topdressing alfalfa fields. If the manure is high in phosphorus content, it is best applied on fields with a low soil test phosphorus result.

What is it worth? Placing a value on manure can be even more difficult than interpreting the analysis report. The simplest method places value on only the nitrogen component. To establish a value based on nitrogen, a “nitrogen cost” is required. The easiest means is to determine the cost of 1 unit of commercial nitrogen, then multiply the commercial nitrogen price by the nitrogen content of the manure. This will give you the value per 1,000 gallons or per 1 ton of manure. Remember, nutrients per unit is determined by the moisture content of the manure. You could also value the manure based on its total macronutrient content. This method is similar to valuing it based on nitrogen, but it would include nitrogen, phosphorus, and potassium. If using this method, you could also include the sulfur content of the manure. This method of valuing manure could also include all of the nutrients available for analysis. While incorporating those additions is probably a bit extreme and

definitely time consuming, all of the nutrients in manure carry value. Reviewing and digesting a manure report can be tricky, but if you break the report down into its individual components, it becomes more manageable. Review each piece of the report on its own and consider its contribution to the manure’s benefits before taking on the icy waters of the entire report. The decision-making process can then move on to prioritizing decision making based on each analyte. This will, in turn, help determine where and how to best utilize the manure to achieve maximum value. Navigating manure analysis reports can prove overwhelming at the start, but achieving familiarity with the individual components will help avoid a Titanic-sized mistake. ■

The author is a nutrient management specialist and sampling director at Rock River Laboratory in Watertown, Wis.

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Sorting out the solids A centrifuge improves flushed liquid dairy manure separation efficiencies for solids and nutrients. by Lide Chen


ome dairies prefer to use flush systems for manure handling because of their ease of mechanization and low labor requirements. Flushing manure results in large amounts of lagoon water that are often applied via irrigation systems to adjacent cropland during the growing season.

The main challenges Solids and nutrients in liquid manure pose challenges to manure handling processes. There are at least three challenges and concerns to consider. First, liquid manure with a high solids content flows into a storage lagoon where some of the solids settle at the bottom of the lagoon, resulting in reduced lagoon capacity. Eventually, the solids at the bottom of the lagoon need to be removed to increase the storage space, which is a costly financial burden for dairy producers. Second, liquid manure with high solids and nutrients (especially phosphorus) limits the land application rate, which means larger areas are needed to apply the same amount of liquid manure. This results in transporting large volumes of liquid manure longer distances, which steadily raises costs. Third, liquid manure with high solids has greater potential to plug pumps, transfer pipes, and sprinkler nozzles. It requires more power to pump the same volume and higher pressure at the pump, thus elevating the risk of ruptured seals and manure spills. Separating solids and nutrients from liquid dairy manure is a big challenge being

Centrifuge-separated solids (left) contain finer particles than screen-separated solids (right). faced by the dairy industry. Many dairy producers are familiar with the benefits of solid-liquid separation and have incorporated solid-liquid separation into their manure management systems. Most of them use primary solid-liquid separation technologies such as settling ponds, inclined screens, rotary screens, and screw presses. Even though the inclined screens are simple and effective for capturing larger particles, their removal efficiencies are generally less than 40% of total solids, 10% to 20% of total nitrogen (TN), and 10% to 20% of total phosphorous (TP). Centrifuges separate solids from liquid using spinning forces that permit removal of fine solids and nutrients more efficiently than inclined screens. In this case study, we intended to measure the separation efficiency of a centrifuge running on a commercial dairy

20 | Journal of Nutrient Management | February 2021

in order to generate science-based information that will help dairy producers make informed decisions regarding the adoption of centrifuges on their farms.

An Idaho case study A year long manure sampling and sample-analysis were conducted on a commercial dairy. The dairy consisted of about 4,000 milk cows housed in both open lots and freestall barns. Sixteen manure lanes were flushed three times each day. The flushed liquid manure first passed through two inclined screens, working in parallel, and then a centrifuge for removing solids. Each month, three samples were collected from the screen-separated solids and the centrifuge-separated solids, respectively. These samples were immediately sent to a commercial lab for nutrient analysis.

The centrifuge tested in this study can remove much finer particles and their associated nutrients after the first separation of solids and nutrients by the screens at the dairy. The centrifuge-separated solids had higher N, P, and K concentrations than those from the screen-separated solids. The one-year averaged P concentration in the centrifuge-separated solids was about two times that of the screen-separated solids. The added centrifuge not only reduced the land area needed for lagoon water applications and reduced frequency and costs of cleaning storage lagoons. It also generated nutrient rich solids that could be composted and marketed as a value-added product. The result was reduced overall manure handling costs and better manure nutrient use. ■ The author is an associate professor at the University of Idaho.

7 Pounds per ton


■ Centrifuge ave. (lb./ton on as received basis) ■ Screen ave. (lb./ton on as received basis)

5 4 3 2 1 0




Apr May



Sep Oct Nov

Figure 2: Total nitrogen (TN) in centrifuge and screen separated solids

Pounds per ton

Consolidate the nutrients

Figure 1: Phosphorus (as P2O5) concentration in centrifuge and screen separated solids

16 14 12 10 8 6 4 2 0

■ Centrifuge ave. (lb./ton on as received basis) ■ Screen ave. (lb./ton on as received basis)




Apr May



Sep Oct Nov

Figure 3: Potassium (as K 2O) in centrifuge and screen separated solids

7 6 Pounds per ton

This is what we learned: 1. Separated solids Seven loads of solids (one load equaled about 25 cubic yards or 12 to 15 tons) were separated by the two screens; meanwhile, about three loads of solids were separated by the centrifuge every day (see photo). Notice that the screen-separated solids are mostly undigested fibers while the centrifuge-separated solids are finer particles. 2. Nutrients in separated solids Phosphorus (P, as P2O5), total nitrogen (TN), and potassium (K, as K 2O) concentrations in the screen separated and the centrifuge-separated solids are shown in the figures. It came across that P concentration in the centrifuge-separated solids is much higher than that in the screen-separated solids. Year-long averages of P, TN, and K concentrations in the centrifuge-separated solids were 3.81 pounds per ton, 8.99 pounds per ton, and 4.42 pounds per ton, respectively. This was compared to the average concentrations of 1.96 pounds per ton of P, 7.68 pounds per ton of TN, and 4.20 pounds per ton of K in the screen-separated solids.

■ Centrifuge ave. (lb./ton on as received basis) ■ Screen ave. (lb./ton on as received basis)

5 4 3 2 1 0




Apr May



Sep Oct Nov

February 2021 | Journal of Nutrient Management | 21


TRAINING SPREADS OUT THE BENEFITS A survey of manure haulers and brokers demonstrated that education positively influenced the knowledge of industry professionals. by Robert Meinen

Figure 1: Distribution of years certified (dashed line marks the average) HAULER 2

HAULER 3 Number


15 10 5 0 1








10 5

9 10 11 12


Years of certification












9 10 11 12





9 10 11 12

Years of certification




5.5 2.5

7.5 5.0 2.5


0 0









9 10 11 12

Years of certification

manure haulers and brokers in Pennsylvania conducted in 2018 demonstrated that education of industry professionals positively influences worker knowledge. This should, in turn, transfer to field-level decisions that are advantageous on agronomic, economic, and environmental levels. Enabling workers with science-based knowledge can have widespread impacts.

What they learn All levels except Hauler 1 have a continuing education requirement. Hauler 1s were not included in our results since surveys were distributed at educational events that group rarely attends.

22 | Journal of Nutrient Management | February 2021


0 0



egislated mandatory certification of custom applicators in Pennsylvania began in 2006 with a unique five-level educational format. The three levels of manure haulers included: 1. Those that only transport but do not land apply manure (Hauler 1). 2. Those that can both transport and land apply manure under the supervision of an owner or manager (Hauler 2). 3. Those who can perform all duties of the other levels and also supervise other haulers (Hauler 3). Two manure broker levels were also designated: Those that take ownership and determine the end utilization of the manure but cannot create Pennsylvania’s Nutrient Balance Sheet (NBS) (Broker 1), and those that receive additional certification to write the NBSs (Broker 2). The Pennsylvania NBS determines application rates and setbacks for farms that import manure. Educational requirements expand with each certification category. Those in the Hauler 1 category complete a verification checklist to ascertain their understanding of important manure transport and stacking principles. A Hauler 2 must study a detailed workbook and successfully complete a proctored certification exam. Other categories require attendance at a certification training followed by successful examination. A survey of certified commercial






Years of certification

The legislation prescribed certification competency criteria includes: • Laws and regulations • Application setbacks • Record keeping • Nutrient behavior and management • Conservation practices • Handling safety and spill response • Biosecurity • Odor and fly nuisance issues At the time of the survey, a total of 808 individuals were certified in the state. The survey asked about knowledge of key certification components, and 171 acceptable surveys were returned. Scores ranged from 28% to 100% correct, with an average across all

Table 1. Summary results from the survey

Certification level* Manure Hauler Level 2 Manure Hauler Level 3 Manure Broker Level 1 Manure Broker Level 2 Total or average for all four categories

Years certified 4.02 7.96 9.94 8.46 6.43 (average)

Test score (% correct) 75.46 78.99 83.95 83.93 78.69 (average)

Work with both liquid and solid manure 23 20 6 5 54 (total)

Work with liquid manure only 35 21 5 5 66 (total)

Work with solid manure only 21 5 7 18 51 (total)

Farms worked on annually 49.4 30.8 51.4 26.4 38.5 (average)

*Manure Hauler Level 1 was not represented at the educational events where surveys were distributed.

levels of 78.7% correct. Scores seemed to rise with the rigor of certification education requirements. An analysis of covariance with score as the response and certification level, role (employee or owner), supervision (supervised or supervisor), number of years certified, type of manure worked with, and number of farms worked with annually as factors and covariates demonstrated that certification level was statistically significant (p value = 0.022). Survey results are presented in Table 1. Across all certification levels, the average length of certification was 6.4 years. However, as demonstrated by the dashed lines in Figure 1, Hauler 2s were only certified for about four years on average, while owner/managers and brokers were certified for eight years or longer. Of all respondents, 84 respondents were supervised by others and 87 supervised others, while 90 identified themselves as employees and 81 as owners/managers. Expected testing scores for those that were supervised

was around 76.5%, while expected scores for supervisors were 81%. Similarly, those listing themselves as employees had an expected score around 76%, compared to 81% for those listing themselves as owners/managers. Less experience and slightly lower testing scores of employees is reasonable, if not expected. This highlights the importance of supervisory roles in the industry.

Broader benefits The table outlines responses to questions concerning whether the individual worked with solid manure, liquid manure, or both. In the Hauler 2 category, 44.3% worked with liquid manure only, which is indicative of services provided to dairy and swine farms. Companies that service liquid systems are more likely to have employees that operate only liquid application equipment. Just five of 46 Hauler 3s (10.9%) worked only with solid manure. Most individuals that handle only solid manure commercially in the state engage in brokered

transfer of poultry or equine manure that is often exported and applied away from the farm where it was generated. This advanced solid manure brokering industry is highlighted by the 18 of 28 Broker 2s (64.3%) who work only with solid manure. Many of these individuals work with or for poultry farms and provide NBSs to farms that import the solid poultry manures. The survey also demonstrated that professional manure handlers work across a wide landscape. The average worker serviced 38.5 farms annually. It stands to reason that practical education that empowers individual field-level decision-making, based both on the latest science and state policies, can have far-reaching positive impacts on farm production and nutrient conservation. ■

The author is a senior extension associate for Penn State University.



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February 2021 | Journal of Nutrient Management | 23

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 DAIRYPOWER BRINGS ITS AERATION SYSTEMS TO NORTH AMERICA Dairypower Equipment, an Irish designer and manufacturer of manure aeration and handling equipment, is now serving the North American market. Suitable for the hog, beef, and dairy industries, the Smart Manure Aeration System is designed to keep manure in a liquid, pumpable state year-round. High-volumes of low-pressure air are pumped through the manure from the base of the storage facility to mix the manure, eliminating the build-up of toxic, volatile gases and the need for tractor agitation. The system creates an aerobic environment that reduces odors

24 | Journal of Nutrient Management | February 2021

and dangerous gas emissions, while increasing manure nitrogen levels by up to 70%. Farmers can purchase less fertilizer, and the manure is ready to pump and spread when they are without agitation, resulting in better air quality and a safer environment. Multiple aeration systems have been installed across North America. Dairypower’s expanding dealer network (including their newlyformed partnership with Agri-Plastics and Agri-Comfort) is ready to help serve and support dairy, beef, and hog farmers. To learn more, go to or call toll-free at 888-231-3575.




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February 2021 | Journal of Nutrient Management | 25




ver 40 years ago, I told a client not to put any fertilizer on his corn crop — zero — after a liberal application of poultry manure. Five months later, and after a record corn yield at the time, I was asked, “How did you know?” Was it an educated guess? The truth is, I didn’t know then — but I do now. Fast-forward 10 years from that event, and we were setting up manure “brokers” who would sell poultry manure to crop farmers at a profit. Manure brokering is standard business today around the country, but it took a lot of research and field trials to get there. Value is whatever someone will pay for an item. The key is to prove the item’s worth. Here are some of the things I’ve done to validate manure’s advantages over the years.

Find the nutrient content The most obvious way is to test manure for nitrogen (N), phosphorus (P), and potassium (K) so you can translate numbers to a crop farmer’s language — they know what fertilizer is worth. However, they may be skeptical of the nutrients’ availability. Nitrogen has its own challenges depending on how the manure was managed, but with new soil testing methods, we know much more N can be available than was previously estimated. Phosphorus and potassium are another matter. I have done replicated plots looking at various rates of manure versus fertilizer compared to no nutrients and timing of application. These were accompanied by soil testing in four periods: fall before applications, early spring after applications, early summer in growing

corn, and then fall after harvest. What I discovered was astounding. Manure nutrients showed very significant availability in the growing season, which then tapered off after harvest. This “bump” was not observed from fertilizer. It makes logical sense. Manure nutrients are sequestered in an organic matrix. As the soil warms up, the microbes do their thing by decomposing organic matter and releasing nutrients. This is analogous to a chelated fertilizer. I will go on record saying manure nutrients are more available than fertilizer. That should add to the value calculation. Because of this sequestering action, there are also environmental benefits, which will be the subject of another article.

Additional elements There are many important secondary and trace elements in manure, such as calcium, magnesium, sulfur, zinc, and iron. Manure is derived from grain (feed), and grain is a seed. I consider seeds as food packages for seedlings until their roots are established. As a consequence, most, if not all, nutrients important to plant growth would be contained in manure — and perhaps a few we don’t recognize as being that important. Just like N, P, and K, these other nutrients can be monetized. It’s a fact that some soils may already provide some of these nutrients, so claiming their full value may be site specific. Anyone who farms in this century knows how valuable organic matter is in the soil. This is perhaps manure’s greatest asset. It provides food for earthworms and microbes, lowers soil bulk density, increases water holding

26 | Journal of Nutrient Management | February 2021

capacity and aggregate stability, and enhances beneficial microbial diversity. It is invaluable — and yet a challenge to assign a dollar value. Though we may have difficulty charging for organic matter, it certainly adds significant value. Unprocessed poultry manure and other solid manures, like from beef feedlots in drier climates, can be an easy sell. The higher the water content, the more diluted the nutrients become on an equal weight basis. Though the nutrient value remains true, the expenses of more specialized handling equipment and additional transportation costs will debit the total value. Various treatments can partition water from most nutrients, and there are circumstances where the water itself can have real value when irrigated on a growing crop at critical times.

Worth the work Raw manure has “baggage,” but crop farmers with sharp pencils overcome that. My rule of thumb is that resistance to use manure comes when it is priced above 50% the equivalent price of chemical fertilizer nutrients. Further processing of manure lightens the load, but those expenses must be added to the selling price to be justified. What I know for sure is that manure improves crop yields over an equivalent of chemical fertilizer. The net result is manure’s true value. ■

The author is the president of Menke Consulting LLC, an agronomic and environmental consulting firm in Greenville, Ohio.

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