September 22, 2017, Ames, IA – I often get asked: “What does the future of the manure industry look like?”

I typically give a little thought and reply: “A lot like it does now. We’ll continue to try to get better at finding ways to more quickly and accurately apply the manure nutrients so we can better capture the fertilizer value.”

I say this because I mean it; manure can be a great fertilizer resource on a farm and when we think about it, livestock production is a critical component of sustainability as the majority of nitrogen, phosphorus, and potassium we feed ends up in the manure and needs to be recycled.

Today I’m going to stop and consider this number a little for you – we are going to focus on liquid manure in Iowa. There is somewhere around 10 billion gallons of manure produced annually (give or take a billion here or there depending on rainfall and the accuracy of my animal populations, the production systems I assume farmers are using, and general variation). It’s a bit hard to fathom this number but I’m going to try a couple ways. The first is if we think of a 40-acre field the manure would be 767 feet tall, or just a little more than the 801 Grand (previously The Principal Building, which as far as I can tell is the tallest building in Iowa). Of course, Iowa really has around one million acres so if we tried to put or manure on all of them each acre would only get around 500 gallons (or you know a little less than 0.02-inches).

As interesting as that is, today I wanted to take a look at slightly different topic, manure application logistics. So we know we are working with approximately 10-billion gallons of manure and if we look in the fall we have approximately 75-days between October and mid-December and then another 30 days of potential application in the spring. So, we are looking at somewhere around 105 application days in a given year (give or take depending on the exact day we start applying and the number of days unsuitable due to soil and weather conditions). That means to get all our manure applied, we need to apply somewhere in the neighborhood of 100-million gallons per day.

So, what does the typical logistics of application look like?

If we think about a drag-line system, when it’s flowing we are probably in the neighborhood of 1,500 gpm for a flow rate; however, there is some setup time involved as we move to new fields. Just for fun, let’s figure that we are somewhere around 50 percent efficient with this system, that is it is running half the time and being reset the other half of the time. If this is true, we’d average around 750 gpm or about 45,000 gallons per hour. Assuming 12-hour days (some companies run longer but I need some time to clean and move from farm to farm) we’d need about 18,500 days to finish all the manure in Iowa. Luckily, there are lots of companies out there to help with this big task.

Similarly, if a manure tanker is used – let’s just say it is a 7300-gallon tank and we get it 95 percent full with each load – and we are hauling three loads an hour, then every hour we are moving 20,000 gallons. To finish hauling all the manure in Iowa in those 105-days, we’d need somewhere around 400 manure spreaders going not stop 12 hours a day.

Luckily, Iowa farmers and commercial manure applicators have recognized this challenge and continuously are purchasing new and better equipment to help ensure they are moving manure from farm to field as cost effectively and responsibly as possible.

For more posts by Dan Andersen, visit his blog – The Manure Scoop.
Published in Other
For years, Fair Oaks, Ind.-based Prairie’s Edge Dairy Farms, LLC, had been trying to find the right technology to remove phosphorus from its manure. Little did Carl Ramsey, farm manager, know that search would lead to a new manure-based fertilizer.
Published in Dairy
August 30, 2017, Ohio - When hay is harvested nutrients are removed from the field. A ton of alfalfa removes approximately 13 pounds of phosphorus (as P2O5) and 50 pounds of potash (as K2O). According to the National Agricultural Statistics Service, Ohio harvested 2.6 tons per acre of alfalfa in 2016.

Many hay fields are not pure alfalfa. The acidic soils of the southern and eastern parts of the state make it difficult to maintain an alfalfa or clover stand so a mixed stand of grass and alfalfa/clover is common. Stands in older fields are often just mostly grass. A grass hay crop will remove just as many nutrients per ton as an alfalfa crop. The big difference is that the annual yields from grass hay fields are usually about 1.3 tons per acre lower than alfalfa fields.

Livestock manure can be used as a fertilizer source to replace nutrients removed through hay harvest. Pen pack beef manure will contain approximately 7.9 pounds of nitrogen (mostly in the organic form), 4.4 pounds of phosphorus (P2O5) and 6.6 pounds of potash (K20) per ton according to OSU Extension bulletin 604. Note that these are older book values and your actual farm manure nutrient levels can vary depending upon the animal's ration, the amount and type of bedding material used and how manure is stored and handled. The recommendation is to sample and test manure at least on a yearly basis. This will provide a more reliable indication of the actual nutrient content of the manure on your farm. For more information about how and when to sample manure, Penn State Extension has a good publication available on-line at

Let's assume a livestock producer wants to use pen pack beef manure to replenish the nutrients in a hay field where he harvested three tons per acre of hay. Since alfalfa and grass hay both remove similar amounts of nutrients per ton, we can assume the three tons of hay removed per acre contained 39 pounds of P2O5 and 150 pounds of K2O. If pen pack beef manure was used to replenish these nutrients, 8.8 tons per acre would be sufficient to replace the phosphorus. However, a rate of 22.7 tons per acre would be needed to replace the potash. The 22.7 ton per acre manure application rate would result in almost 100 pounds of P2O5 being applied per acre, far more than was removed in the three tons of hay.

A farmer would need to be cautious about using this practice repeatedly and growing the soil phosphorus level. It takes about 20 pounds of phosphorus applied to a field to raise the soil test level one pound per acre or two parts per million. So if the soil test level is low, the additional phosphorus from the manure would not raise the soil phosphorus level much in a single year.

The key to using livestock manure to replace the nutrients removed through hay harvest is to get even distribution of the manure across the entire field. Having mowed hay fields as a teenager, where bedded pack manure was applied, I would strongly urge an even distribution pattern across the field. Avoid large clumps that will plug the mower or interfere with regrowth.

If you are unsure how many tons per acre your solid manure spreader applies there is a simple way to make a determination. Make a heavy plastic piece that is 56 inches by 56 inches. Fasten it to the ground with weights on the corners and apply manure across the plastic. Fold up the plastic and weigh the manure captured. Many people use a bathroom scales for this. One pound of manure captured on the plastic is equivalent to one ton of manure applied per acre. Thus, if you captured 10 pounds of manure the application rate was 10 tons per acre.

It is common for county extension offices to have farmers ask; "Can manure be applied between cuttings"? The answer is "yes". Farmers commonly use liquid swine and liquid dairy manure between cuttings to replace soil nutrients and "boost" regrowth of the forage crop in northwest Ohio. There is the potential to damage the crowns of the forage plants but most farmers seem to like the results of the manure application. Solid manure could also be applied between cuttings instead of waiting until fall to apply the manure. The manure application should take place as some as the hay is baled.

Liquid beef manure is also being used to replace nutrients in hay fields. Liquid beef manure we have sampled has contained 40 pounds nitrogen (about half in the organic form and half in the ammonium form), 35 pounds of phosphorus (P2O5) and 30 pounds of potash (K20) per 1000 gallons of product. Applied with a drag hose, this can be an excellent fertilizer for a forage.

A final cautionary note regarding manure application to forage fields: If manure is coming from a herd with animals infected by Johne's disease, that disease can be transmitted by manure to healthy cattle. According to a publication from the US Dairy Forage Research Center at Madison Wisconsin and authored by Michael Russelle and Bill Jokela, the Johne's bacterium can survive on hay. Therefore, those authors' recommendation is that in herds with Johne's, manure should not be applied as a topdressing on fields that will be harvested as dry hay.
Published in Other
All farmers strive to be good stewards of the soil in their fields and the surrounding environment, but they need both solid research and the right tools to optimize their success.

Phosphorus is obviously of particular concern to crop farmers.

“The harmful algae blooms occurring in Lake Erie appear to be from increasing amounts of dissolved phosphorus reaching the lake,” says Glen Arnold, associate professor and field specialist in Manure Nutrient Management Systems at Ohio State University Extension. “The phosphorus in livestock manure is less likely to reach surface waters than the phosphorus in commercial fertilizer, as the phosphorus in livestock manure is slower to become soluble once applied to fields.”

However, Arnold notes that the over-application of livestock manure can raise soil phosphorus to very high levels and result in the element being lost through both surface runoff and through subsurface drainage tiles.

Arnold believes finding new ways of applying manure to growing crops and incorporating the manure more effectively could better assure the phosphorus stays put. His research on the application of manure to growing crops first started with topdressing wheat plots in Putnam County, Ohio, in 2004.

“We wanted to capture value from the nitrogen in manure and open up new windows of application for farmers, instead of them usually applying large amounts of manure in the fall after harvest,” he explains.

Arnold and his team approached swine farmers with finishing buildings for the wheat plot experiments, as swine manure has more nitrogen per gallon than dairy or beef manure. The Putnam County Extension Office and Soil & Water Conservation District collaborated on planning, flagging the replicated plots, field application and harvesting, with plots either receiving urea fertilizer or swine manure. When the results were analyzed, wheat yields under the manure treatments were equal to or greater than the urea treatment most of the time.

By 2009, Arnold, his colleagues and county extension educators in nearby counties were using swine manure to side dress corn plots.

“We removed the flotation wheels from a manure tanker and replaced them with narrow wheels so the manure tanker could follow the tractor down the cornrows,” he says. “The yield results were very positive as the manure treatments were similar to the commercial fertilizer treatments. During unusually dry growing seasons, the manure treatments out-yielded the commercial manure treatments. The same occurred during unusually wet growing seasons as well.”

In addition to the swine-finishing manure side dress plots, during the past year the team tried liquid beef manure and liquid dairy manure, enhanced with commercial nitrogen, to side dress corn plots.

“We used a manure tanker and Dietrich toolbar,” Arnold says. “The beef manure plots performed as well as the swine manure plots. The dairy manure plots also preformed very well, which opens many possibilities for dairy producers to sidedress corn in the years ahead.”

At this point, the team has also completed a third year of side dressing emerged corn with swine manure in Darke County, Ohio, using a drag hose. The drag hose was pulled across the emerged corn through the V3 stage of growth, and the manure incorporated during application using a seven-row VIT unit. Over three years, the corn side dressed with manure averaged 13 bushels per acre more than corn side dressed with urea ammonium nitrate.

In terms of cost differences between urea and manure, Arnold notes that farmers have to eventually land-apply the manure regardless of whether it’s applied to a growing crop or not.

“Capturing the nitrogen value pays for the cost of applying the manure,” he says.

He also believes a drag hose is faster, more efficient and alleviates soil compaction concerns compared to using a manure tanker. Drag hoses also provide flexibility in that the manure can be applied anytime from the day the crop is planted through the V3 stage of corn growth, a six-week window in Ohio if the corn is planted in late April.

In these experiments on application of manure during the growing season, Arnold and his colleagues never measured phosphorus runoff, but he says that if manure is applied in the fall, more than 50 percent of the nitrogen is generally lost, and the tillage to incorporate the manure at that time causes more soil erosion than application during crop growth.

Farmers do have to watch over-application of manure to growing wheat as it will lead to the wheat field blowing flat in June in Ohio. On corn, Arnold says there is nothing to stop a person from over-applying but the extra nitrogen would be wasted.

All-in-all, Arnold believes the application of manure to growing crops works very well. He says the farmers who have participated in the on-farm plots have been pleasantly surprised at how well livestock manure has worked as a sidedress nitrogen source for corn and as a top dress to wheat.

“In addition to providing nitrogen for the corn crop, the manure can also provide the phosphorus and potash needed for a two-year corn-soybean rotation without applying excess nutrients,” he says.

In order to convince as many livestock producers as possible of the economic and environmental advantages of applying more manure to growing crops and applying less manure after the fall harvest season, Arnold and his team will allow farmers to see results first-hand. Because he’s found that farmers who participated in the sidedress plots using a manure tanker are very interested in using a drag hose, Arnold has obtained funds from several companies to build two 12-row drag hose sidedress toolbars. He expects to have them available for loan during the 2017 growing season.

“The plan is to loan the toolbars to both livestock producers and commercial applicators,” he says. “We hope to loan them out to more than a dozen participants this summer.”

Published in Applications
August 17, 2017, Fruitland, IA — All farmers know that crops need nutrients to grow, particularly carbon. That's why they spread manure or compost on their fields. But compost fades fast — half of its carbon degrades in five to eight years.

In recent years, biochar has been hailed by some as an alternative to manure or compost, but  biochar is expensive and poor quality biochar can increase the soil's acidity, damaging crops. READ MORE 
Published in Applications
June 8, 2017, Charleston, WV – West Virginia’s Department of Agriculture says plans have been written for managing fertilizer and other nutrients on 90,000 acres in the state’s eight-county Chesapeake Bay drainage region.

Agriculture Commissioner Kent Leonhardt says West Virginia is furthest along among the bay’s watershed states toward the goal, which helps restore land for productive use. READ MORE
Published in State
Beef and dairy farmers obviously want to keep as much nitrogen as they can in the soil after they apply any type of manure to their fields, but there aren’t many recommendations out there about whether more N is retained through applying raw dairy manure or digestate (from anaerobic digesters).
Published in Other

January 18, 2017 – The Livestock and Poultry Environmental Learning Center has partnered with the Manure & Soil Health team to present four roundtables aimed at improving knowledge and understanding about the role of manure in soil health.

The four, hour-long roundtables will consist of a panel discussion with two to three experts who will be asked to summarize their current understanding of each roundtable topic. Each panel will also include a practitioner who will share perspective on critical information needs of farmers and advisors and field experiences relative to use of manure. Panels will be moderated to encourage interaction with audience. Roundtable participants will be invited to ask questions of panelists and share expertise and experience through polling pods and a chat box.

All of the roundtables start at 11 a.m. CT (noon ET) and in the following order:

  • Feb. 9, 2017 – Manure & soil health testing (Dr. Bianca Moebius-Clune, Donna Brandt, Russell Dresbach, Geoff Ruth)
  • Feb. 16, 2017 – Manure & soil biology (Rhae Drijber, Michele Soupir, Dr. Jonathan Lundgren)
  • Feb.23, 2017 – Manure & soil erosion, runoff, and losses (Nathan Nelson, John Gilley, Mike Kucera, Andy Scholting)
  • March 9, 2017 – Manure & cover crops (Tim Harrigan, Barry Fischer, Heidi Johnson, Sarah Carlson)

Attendees are asked to register for the dates that correspond to the topics they are interested in. After registering, a confirmation email containing information about joining the meeting will be sent.

If a microphone and speakers are available on the computer being used, phone line participation is not needed. For those new to Zoom, three short videos may prove helpful:

Published in Other

December 8, 2016, Rossburg, OH – When Ohio farmer Tom Harrod first heard about sidedressing hog manure, he was skeptical.

He went to a county extension program after talking to some farmers about their use of hog manure on growing corn, then he decided to give it a try. After achieving good yields without using commercial fertilizer, he became sold on the practice. Now, Harrod says, it’s driving profits in his operation. READ MORE

Published in Swine


Each year, more than 14 million tons of chicken litter is generated in the U.S. Studies have shown that using poultry litter to fertilize crops can be as effective as using synthetic fertilizers.

In a new study, researchers at the USDA’s Agricultural Research Service have calculated how much chicken litter farmers need to apply to cotton crops to maximize profits.

“Most research focuses on the amount of poultry litter needed to maximize crop yields,” says Haile Tewolde, lead author of the study. “We wanted to know if aiming for maximum yield always makes economic sense for farmers.”

Tewolde and his colleagues found that it doesn’t. Using less chicken litter than what was needed to maximize crop yields actually increased profits for farmers. Profits increased even though crop yields were lower.

It might appear that higher crop yields would lead to higher profits. But using more fertilizer also increases costs for farmers. The researchers predicted that once an optimal amount of fertilizer had been applied to crops, any more would raise costs more than profits.

The study was conducted in two farms in Mississippi. Researchers applied varying amounts of chicken litter as fertilizer on replicated plots then compared yield and profitability. They also compared the use of synthetic fertilizers and chicken litter.

They found that chicken litter applications over a certain level did not result in net economic gains. Instead, it led to economic losses even though yields were somewhat higher.

Maximum cotton yields were achieved by applying between 9,000 to 12,000 pounds of chicken litter per acre. In contrast, applying about 7,000 pounds of chicken litter per acre each year was enough to maximize profits.

The researchers also confirmed studies that showed chicken litter to be as effective – sometimes more so – than synthetic fertilizers.

If farmers can use less poultry litter and still maximize profits, pollution can be managed more effectively.





Published in Poultry

October 25, 2016, Boonsboro, MD — “Nutrient management is alive and well in Maryland,” according to University of Maryland Extension agent Jeff Semler. One aspect of nutrient management is manure injection, which was featured during a recent field day at Debaugh Dairy Farm in Boonsboro.

The field day was funded in part by a grant from the Chesapeake and Atlantic Coastal Bay’s Trust Fund, and attracted more than 150 people, most of them farmers. READ MORE

Published in Dairy

October 13, 2016, There are more chickens in the United States than people in the entire world. Raising huge numbers of chickens generates large quantities of waste. This waste includes feces, feather, and bedding materials – collectively called chicken litter.

Each year, more than 14 million tons of chicken litter is generated in the U.S. Other poultry – such as turkeys, ducks, and geese – also contribute litter. Poultry litter is often recycled as manure by farmers. Studies have shown that using poultry litter to fertilize crops, such as cotton, can be as effective as using synthetic fertilizers.

In a new study, researchers at the U.S. Department of Agriculture’s Agricultural Research Service have calculated how much chicken litter farmers need to apply to cotton crops to maximize profits.

"Most research focuses on the amount of poultry litter needed to maximize crop yields," says Haile Tewolde, lead author of the study. "We wanted to know if aiming for maximum yield always makes economic sense for farmers."

Tewolde and his colleagues found that it doesn't. Using less chicken litter than what was needed to maximize crop yields actually increased profits for farmers. Profits increased even though crop yields were lower.

It might appear that higher crop yields would lead to higher profits. But using more fertilizer also increases costs for farmers. The researchers predicted that once an optimal amount of fertilizer had been applied to crops, any more would raise costs more than profits.

The study was conducted in two farms in Mississippi. The researchers applied varying amounts of chicken litter as fertilizer on replicated farm plots. Then, they compared yield and profitability between the seven plots. They also compared the use of synthetic fertilizers and chicken litter.

They found that chicken litter applications over a certain level did not result in net economic gains. Instead, it led to economic losses even though yields were somewhat higher.

Maximum cotton yields were achieved by applying between 9,000 to 12,000 pounds of chicken litter per acre. In contrast, applying about 7,000 pounds of chicken litter per acre each year was enough to maximize profits.

The researchers also confirmed studies that showed chicken litter to be as effective – sometimes more so – than synthetic fertilizers.

Poultry litter contains high levels of nitrogen, an important nutrient for plants. It also contains other minerals needed by crops, including phosphates and potash. Using poultry litter as manure also recycles a waste product and can benefit the environment.

However, using too much poultry litter can cause environmental pollution. Nitrogen and phosphorus in the poultry litter can dissolve in runoff from storms. These dissolved nutrients can pollute surface and ground waters. If farmers can use less poultry litter and still maximize profits, pollution can be managed more effectively.

"Ten to 15 years ago it was not common to use poultry litter as fertilizer for row crops such as cotton," says Tewolde.

Today, there is increasing acceptance of poultry litter as fertilizer, including in commercial farms. But research on the use of poultry litter as fertilizer is not often geared towards maximizing profit in larger, commercial farms.

"This is the first comprehensive study looking at chicken litter use and profitability in commercial farms," says Tewolde. "We are the first to identify ways to calculate optimal rates of applying chicken litter manure and maximize earnings at this scale of farming."

One benefit of conducting the study on commercial fields is that "farmers can start applying our findings straightaway," says Tewolde.

Though the study was conducted in Mississippi, it has wider implications.

"The approach we use to determine optimal rates of chicken litter application will be applicable in other cotton-growing areas around the country," says Tewolde.

Tewolde's research has been featured in Crop Science.

Published in Poultry

October 21, 2016, Columbus, OH – A new app from Ohio State University allows growers to compare the effectiveness of different management decisions within fields. The aim, in part, is to improve water quality throughout the state.

Called Ohio State PLOTS, the free app allows growers, as well as consultants and others who support growers, to design replicated plot layouts by creating on-farm trials that can compare hybrids, seeding populations, fertilizer rates and nutrient management systems, among other practices and inputs, said John Fulton, precision agriculture specialist for Ohio State University Extension.

The app allows users to digitally compare various treatments within their fields to determine the best management plan for their fields, before extending financial or labor resources, he said.

Fulton, who is also an associate professor in the Department of Food, Agricultural and Biological Engineering in Ohio State’s College of Food, Agricultural, and Environmental Sciences, said the app was designed as a tool to help improve water quality in Ohio by allowing users to fine-tune nutrient management more accurately and reliably for a farm operation and by encouraging on-farm studies.

“The app is a means where growers can set up trials specific to nutrient management to allow them to see what management decisions best impact their farm and offer the best financial and fertility decisions,” he said. “Users can fine-tune their nutrient management and maximize profits, all while minimizing environmental concerns.

“The app is a great way to help growers ensure their farm remains productive and profitable, as well as aiding in making smarter choices for cleaner water.”

The app, which is available for both Apple and Android devices, includes a random number generator that removes human error when developing plot layouts. The app allows users to define an experiment that compares various response parameters such as yield, stand counts, crop health and varieties, Fulton said.

“The app statistically analyzes these parameters,” he said. “Without having to be a statistician, users can review the mean or average comparisons within the summary report and determine the best fit for their farm management strategy.”

The report details information the user has entered regarding a specific trial, notes and photos they’ve taken throughout the growing season, and statistically analyzes parameters, Fulton said. The report can be shared with crop consultants and agronomists through the app. Users can also choose to keep the report private and stored in the cloud or exported as a CSV file to be used in programs such as Excel and Access, he said.

“The app does the statistical setup and analysis for you,” Fulton said. “It helps growers in implementing nutrient management strategies that are a win for their business operations and a win for environmental practices.”

The app can be downloaded free by searching for “Ohio State Plots” in the App Store and Google Play Store. More information on the app can be found at

Published in Other

October 12, 2016, Bismark, ND – I would like to look past harvest today and discuss manure application and valuation to give you something to ruminate on while sitting in the combine.

Rate of manure application will vary depending on crop nutrient needs, soil type, and the manure nutrient concentration and availability. READ MORE

Published in Beef

September 29, 2016, Washington, DC – A new $2 million grant from the U.S. Department of Agriculture (USDA) – awarded to a multidisciplinary team from the University of California, Davis, University of Minnesota, University of Maine, the USDA Agricultural Research Service's Beltsville Agricultural Research Center, USDA's Economic Research Service Resource and Rural Economics Division, the Produce Safety Alliance, and The Organic Center – will address one of the most pressing issues for the organic community: how to use manure effectively in organic farming in ways that foster healthy soil and minimize risks to food safety.

Announced recently by the USDA with funding provided by its Organic Agriculture Research and Extension Initiative (OREI), the grant (exact amount $1,999,848) will support research examining the relationship between manure use in improving soil health and food safety, concentrating on organic fresh produce production.

The new grant implements a research plan developed by UC Davis, The Organic Center, and the Organic Trade Association (OTA) during their 2016 OREI planning grant. The long-term goal of the project is to provide critical information for guidelines on risk mitigation of foodborne pathogens for organic and sustainable agriculture.

"With this grant, we can now engage in specific research using the knowledge base that we've built, and The Organic Center welcomes our role in helping to get the word out about this vital issue," said Dr. Jessica Shade, director of science programs at The Organic Center.

The impetus for these grants has been the ongoing implementation process of the Food Safety Modernization Act (FSMA) by the U.S. Food and Drug Administration to improve food safety. In new rules implementing the FSMA regulations, changes were proposed relating to the use of compost and manure and the required interval that untreated manure could be applied and crops harvested. This is of particular importance for the organic sector, as many certified organic producers rely on animal-based soil amendments such as manure and compost to improve soil fertility and quality instead of chemical fertilizers.

Several studies have shown that the use of manure and compost has multiple positive environmental impacts: increased soil health, higher soil biodiversity and reduced erosion. The improved soil health and microbial diversity in organic soils have the potential to control the presence of soil pathogens, which can impact food safety. But little research has examined the specific wait periods between manure application and crop harvest required to control pathogens, and how pathogen presence interacts with healthy soil.

"By developing an innovative, customized risk-assessment based on good agricultural practices used within the organic industry related to raw manure and soil health, the project will benefit organic farmers and consumers by providing strategies to maintain the value of raw manure soil amendments while limiting food safety risks," said Professor Alda Pires, one of the team's principal investigators from UC Davis.

For more information on The Organic Center and the science behind organic food and farming, visit

Published in News

September 14, 2016, Fort Atkinson, WI – The University of Wisconsin Discovery Farms Program has been looking at nitrogen efficiency by tracking all sources as it cycles through the growing season from the soil to the corn plants.

Megan Chawner has worked with this study, evaluating farms in five different regions of Wisconsin, including the Rock River Basin. READ MORE

Published in News


It’s summer and temperatures often break the 100 degree Fahrenheit mark. No doubt, we still have a few days before fall when the temperatures will go beyond 100.

Why would I be thinking about temperature and nitrogen management at the same time? My simple answer is that manure nitrogen can be a valuable crop nutrient when conserved and managed. Temperature plays a part in that.

The crude protein concentration in diets is formulated to provide nitrogen and amino acids for animal production and growth. Diets with concentrations greater than needed result in animals excreting more nitrogen. Diets with concentrations less than needed may result in reduced production (less milk made or lower growth rates). Targeting formulations to animal needs has the greatest potential to optimize nitrogen use efficiency.

Data from feed inventory analysis on seven commercial dairies in California identified that 16 to 27 percent of total nitrogen in feedstuffs delivered to the facility were recovered in milk and animal tissue (growth). The other 84 to 73 percent of nitrogen was assumed excreted. For 100 pounds of nitrogen fed to these dairy herds (all replacements were reared on-site), roughly 73 to 84 pounds would be excreted.  

What happens to the excreted nitrogen? That depends on the animal housing and manure collection/storage process. Most of the nitrogen excreted by dairy animals is in the organic form. Let’s look at the highlights of the nitrogen cycle. Organic nitrogen needs to be mineralized to ammonium, a plant available form of nitrogen. It’s not particularly mobile. It clings to negatively charged particles including clay. It may also off gas to the atmosphere as ammonia. Or, ammonium may be converted to nitrite and nitrate through nitrification. Nitrate is also plant available. Unfortunately, since nitrate has the same negative charge as most soil particles, it does not cling to soil particles. In fact, it leaches easily when excess rain or irrigation water is applied. Nitrate may be fully denitrified and leave the solid/liquid system as N2 gas. This colorless, odorless gas makes up about 78 percent of the air we breathe. Microbes and enzymes present in the soil are responsible for nitrogen metabolism.

Most nitrogen in manure is in the organic fraction. The fact that it’s organically bound is great for the soil, as organic amendments are a great way to help build up soil organic matter content. However, the timing of availability of organic nitrogen is not as predictable as we’d like it to be in order to manage crop nutrient needs based on organic nitrogen applications.

Urea is the next largest form of nitrogen excreted in cattle urine. Urea is no stranger in farming. In fact, synthetic urea is used as a fertilizer. When entering the dairy manure stream, urea is often hydrolyzed to ammonium (if in a moist or wet environment) and then either volatilized as ammonia or it stays in solution. Ammonium in liquid manure is plant available. Ammonium will volatilize. Volatilization increases as pH, temperature, and wind speeds increase. Site-specific conditions, including management, impact how much ammonia is volatilized. When liquid manure is managed to conserve nitrogen, the next step is to manage it to minimize losses. Ammonium can undergo nitrification to nitrate after land application. Matching application timing and rate to crop needs is key to be efficient with nitrogen incorporation into plant matter and not lost to the environment. The nitrification process requires an oxygen rich environment [note: very few dairy lagoons in California would promote nitrification within the lagoon]. Ammonium may also remain adhered to soil particles. Under our hot summer conditions, urea in open lots may not hydrolyze as the moisture rapidly dissipates. Urea that hydrolyzes in open lots will likely volatilize as ammonia.

Rapid drying of open lot feces and urine has the greatest potential to conserve nitrogen. Keeping corrals dry and well managed will minimize pockets of wet material. Some operators harrow daily to break up clods and aid in drying. This is helpful to reduce fly populations as well as conserve urinary nitrogen. Management of solid manure through active composting is great to reduce microbial populations present, however it will result in loss of ammonium as piles are turned and rewetted. Flush systems regularly collect feces and urine from concrete lanes and transfer the material to a liquid storage/treatment structure. Urea is hydrolyzed and ends up in the liquid system as ammonium. The amount of this volatilized to the atmosphere will depend on wind speed, pH, temperature, and exposure surface. If you actually smell ammonia at the bank of a lagoon, you might want to check the pH and see what modifications are possible to lower the pH to something closer to seven.

First, identify what you expect the technology to accomplish (its job description) before you ask any questions about the technology. If you want a technology that removes solids from a liquid waste stream there are many different types and they all function a bit differently. If this is your focus, carefully evaluate your bedding source, amount used and particle size length. Experience shows us that particle length of different bedding sources varies, resulting in big differences in how separators or technologies work from dairy to dairy. Alternatively, if you want a technology that reduces the amount of nitrogen you emit to the atmosphere from your manure treatment/storage area, then perhaps you’re considering monitoring and management of pH, temperature, and wind speed. Transferring nitrogen from the liquid to the solid phase opens up greater opportunities for nitrogen exports.

Carefully identify the job description and expectations (manure function, employee labor, etc.) of any new management practice or technology before you consider it for your facility. Do your due diligence with air and water regulatory agencies before considering purchase and installation.

Yes, the nitrogen cycle is complex. Yes, nitrogen is very important to manage in order to maintain groundwater quality. Yes, there are things one can do. First, talk with your dairy nutritionist to be sure you’re not over feeding nitrogen to your animals. Second, evaluate manure handling to optimize nitrogen conservation once excreted. Keep solids in corrals dry in summer. Regularly flush lanes to collect and contain urea/ammonium nitrogen. Third, talk with your crop consultant about organic nitrogen variability.

Dr. Deanne Meyer is a livestock waste management specialist in the department of animal science at the University of
California – Davis.




Published in News

June 22, 2016, Ames, Ia – Based on current research results from Iowa and neighboring states, the Using Manure Nutrients for Crop Production publication (PMR 1003) was recently updated to reflect new manure nutrient availability ranges for crop production.

Beef cattle and dairy nitrogen availability ranges are now 30 to 50 percent of the total nutrients applied, and phosphorus ranges are 80 to 100 percent of total nutrients applied. These ranges increased slightly from 40 percent to 50 percent for the upper end of the nitrogen range and 60 percent to 80 percent for the low end of the phosphorus range.

Manure nutrient availability values are important when it comes to manure application, since the manure rate to supply crop available nutrients is calculated based on the specific manure source being used.

“For manure nitrogen and phosphorus, there is usually a mix of organic and inorganic materials that varies among manure sources, production systems, bedding, storage systems and handling,” said John Sawyer, professor and extension soil fertility and nutrient management specialist at Iowa State University. “These ranges account for the variety of factors that can affect nitrogen and phosphorus availability to crops.”

Additional text describing the table of manure nutrient availability values was added, along with the new URL for the revised Corn Nitrogen Rate Calculator website.

The Using Manure Nutrients for Crop Production publication includes information about manure nutrient availability for crops, manure nutrient supply, manure nutrient application recommendations, adjusting for manure nitrogen volatilization, and more. You can download the revised document online for free at the Extension Store.

Published in Swine

May 9, 2016 – Including manure in your nutrient-management plan comes with benefits and drawbacks. Weighing the economics, community relations, and other considerations can help you decide if it’s going to be useful in your operation.

Depending on the species, manure will be valued from $6 to $35 per 1,000 gallons of manure, says Kevin Erb, University of Wisconsin Extension specialist. READ MORE

Published in Dairy

May 6, 2016, Balaton, MN – The nearly 8,500 tons of manure Jon Greenfield’s 1,000 head of Black Angus cattle produce annually is a valuable nutrient resource for his crops. The brown gold not only contains nitrogen, phosphorus, potassium, and other nutrients but also adds organic matter to the soil. In turn, this can amend soil structure, aeration, soil moisture-holding capacity, and water infiltration.

For years Greenfield, who grows 1,400 acres of corn and soybeans in Balaton, Minnesota, has been applying a flat rate of manure across his fields. READ MORE

Published in Beef
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