This uncertainty increases the risk of over-applying or under-applying nutrients to the field.
The risk is greatest with nitrogen (N), which can easily move out of manure during storage and is a source of drinking water concerns. However, there are ways that producers can lower that risk. One of those ways is by getting manure tested.
Studies from Minnesota and elsewhere have shown how important it is to get manure tested rather than relying on published book nutrient values, says Gregory Klinger, Extension educator for the University of Minnesota.
Book values suggest a specific nitrogen credit for specific manure types. They are useful for planning where to spread your manure, but can lead to over- or under-application of nutrients if used as the basis for actual application rates.
Manure nitrogen content is highly variable. Consider the case of liquid dairy manure, which has book values of 31 or 32 lbs N/1,000 gallons in Minnesota. Different studies on lab-tested dairy manure have found that individual manure N contents are typically anywhere from 20 to 40 percent higher or lower than these book values.
With a book value of 32 lbs N/1,000 gallons, the nitrogen in your dairy manure could be anywhere from 19.2 to 44.8 lbs/1,000 gallons. That creates quite a risk of over- or under-applying nitrogen.
Agitating and testing manure reduces that variability. While there is still variability in the results you get when you test manure, it is lower than relying on book values. Studies suggest 10 to 30 percent for unmixed manure, but as low as three to seven percent for well-mixed or agitated manure.
That means if you have 24 lbs N/1,000 gallons in your manure and it has been agitated and analyzed, you could reasonably expect the measured results to be from 22.3 to 25.7 lbs/1,000 gallons.
Much better than the 19.2 to 44.8 lbs/1000 gallons range you could expect without testing. While dairy manure is the example used here, these trends are true of other manure sources as well. Just by mixing and analyzing your manure, the risk of over- or under-applying nitrogen goes down immensely.
If you can't agitate your manure, try to take a number of subsamples from across the manure stockpile and mix them. Studies show that 15 to 25 subsamples will get the variation below 10 percent. For manure with an actual nitrogen concentration of 24 lbs N/ton, this would mean the N content reported by the lab would likely be 21.6 to 26.4 lbs/ton.
Many soil scientists in the Midwest have noted that when nitrogen application rates are less than 25 pounds above or below the best rate for a field, it usually has a negligible effect on yields and profitability, regardless of form.
That means that you don't need to hit a magical number that is best for your field, you just want to get within 25 pounds of that number. Testing manure will minimize how much uncertainty there is in manure N concentrations and help you hit that goal.
It was the first step in an ongoing study by dairy scientists, engineers and agronomists to see how a cow's breed and forage consumption affect the greenhouse gases generated by her gut and her manure.
The U.S. dairy industry has set a goal of reducing its greenhouse gas emissions by 25 percent by the year 2020, and UW–Madison researchers are helping identify strategies to accomplish that. | For the full story, CLICK HERE.
Screw Press Separation and Centrifugation are the two established technologies currently being investigated for their impact and effectiveness in removing, off farm, large quantities of solids from farm slurries and digestates i.e. feedstock.
Separation of feedstock produces a solids fraction containing a high proportion of phosphorus (P) which is more economical to transport off farm for both agricultural and non-agricultural purposes.
This is especially important for Northern Ireland, since oversupply of P to grassland has increased soil P levels beyond crop requirement optimum, leading to increased risk of P runoff to water courses and a negative impact on water quality. | For the full story, CLICK HERE
Iowa State University researchers have completed testing of a key component of a new concept for disposing of animal carcasses following a disease outbreak.
The research someday may help producers facing animal disease emergencies, such as in 2015 when avian influenza resulted in disposal of millions of chickens and turkeys in Iowa and other states.
Jacek Koziel, associate professor of agricultural and biosystems engineering, said animal health emergencies occur around the globe each year due, not only to disease, but also to hurricanes, flooding, fire and blizzards.
These incidents often require the disposal of numerous animal carcasses, usually accomplished via burial. In research published recently in the scientific journal Waste Management, Koziel and his team analyzed a method that could help livestock, poultry and egg producers deal more efficiently and safely with crises that lead to sudden increases in animal mortality.
Koziel and his team focused their research on improving on-farm burial, the method most commonly employed for large-scale carcass disposal due to its low cost and ability to quickly reduce the spread of airborne disease and foul odors. But emergency burial can contaminate nearby water resources with chemical and biological pollutants, and many locations in Iowa are considered unsuitable for such practices by the Iowa Department of Natural Resources.
Buried carcasses also decay slowly, sometimes delaying use of burial sites for crop production and other uses for years, Koziel said.
To overcome these problems, the researchers studied a hybrid disposal concept conceived at the National Institute of Animal Science in South Korea following a massive outbreak of foot-and-mouth disease in 2011.
The method combines burial with aerobic digestion, a method commonly used for treating sewage in which air is pumped through the content to speed decomposition.
The experiment also included burial trenches lined with flexible geomembranes like those used to prevent seepage from landfills and wastewater treatment ponds to protect water quality. The researchers then injected low levels of air into the bottom of the trench to accelerate carcass decomposition and treat the resulting liquid contaminants.
The experiment tested the performance of the aerobic component of the hybrid method in a lab using tanks containing whole chicken carcasses, water, and low levels of oxygen that occasionally dropped to zero as would be likely in emergency burial trenches.
Results of the study showed low levels of oxygen accelerated carcass decay significantly, reducing carcass mass by 95 percent within 13 weeks, while similar tests without air produced no noticeable decay. The air and water used for the experimental method create an ideal environment for bacteria to break down the carcasses quickly, a "shark tank," as Koziel described it.
Chemical contamination in the liquid waste met U.S. Environmental Protection Agency criteria for safe discharge to surface waters. The hybrid method also eliminated two common poultry pathogens, salmonella and staphylococcus. Aeration also reduced odorous gases sometimes associated with mass burial.
Koziel said the the encouraging laboratory results could pave the way for follow-up field studies that will include evaluation of alternative geomembrane liners, aeration system designs and components, and performance testing of the complete hybrid disposal system.
The research was supported by funding from the Korean Rural Development Administration.
Constructed wetland technology, uses sand, plants, and a network of pipes, to drain the moisture out of the sludge and dries the remaining solids into a concentrated and far more valuable fertiliser. | READ MORE
The researchers are presenting their results today at the 255th National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world's largest scientific society, is holding the meeting here through Thursday. It features more than 13,000 presentations on a wide range of science topics.
The idea for the project germinated on Crete, where Alexander Bismarck, Ph.D., noticed goats munching on summer-dry grass in the small village where he was vacationing. "I realized what comes out in the end is partially digested plant matter, so there must be cellulose in there," he recalls.
"Animals eat low-grade biomass containing cellulose, chew it and expose it to enzymes and acid in their stomach, and then produce manure. Depending on the animal, up to 40 percent of that manure is cellulose, which is then easily accessible," Bismarck says. So, much less energy and fewer chemical treatments should be needed to turn this partially digested material into cellulose nanofibers, relative to starting with raw wood, he conjectured.
After working with goat manure, Bismarck, who is at the University of Vienna, Austria, his postdoc Andreas Mautner, Ph.D., and graduate students Nurul Ain Kamal and Kathrin Weiland moved on to dung from horses, cows and eventually elephants. The supply of raw material is substantial: Parks in Africa that are home to hundreds of elephants produce tons of dung every day, and enormous cattle farms in the U.S. and Europe yield mountains of manure, according to Mautner.
The researchers treat the manure with a sodium hydroxide solution. This partially removes lignin -- which can be used later as a fertilizer or fuel -- as well as other impurities, including proteins and dead cells. To fully remove lignin and to produce white pulp for making paper, the material has to be bleached with sodium hypochlorite. The purified cellulose requires little if any grinding to break it down into nanofibers in preparation for use in paper, in contrast to conventional methods.
"You need a lot of energy to grind wood down to make nanocellulose," Mautner says. But with manure as a starting material, "you can reduce the number of steps you need to perform, simply because the animal already chewed the plant and attacked it with acid and enzymes. You inexpensively produce a nanocellulose that has the same or even better properties than nanocellulose from wood, with lower energy and chemical consumption," he says.
The dung-derived nanopaper could be used in many applications, including as reinforcement for polymer composites or filters that can clean wastewater before it's discharged into the environment, Bismarck says. His team is working with an industrial consortium to further explore these possibilities. The nanopaper could also be used to write on, he says.
The researchers are also investigating whether the process can be made even more sustainable, by first producing biogas from manure and then extracting cellulose fibers from the residue. Biogas, which is mostly methane and carbon dioxide, can then be used as a fuel for generating electricity or heat.
"We need to know how feed affects methane production, but we also need to know how it affects other aspects of the farm operation, like daily gains in animals, milk production, and feed efficiency. Farmers want to help the environment, and they need to know what the trade-offs will be, which is why we took a holistic approach looking at the overall impacts," explains Dr. Karen Beauchemin, beef researcher from Agriculture and Agri-Food Canada (AAFC).
Researchers and farm system modellers from Agriculture and Agri-Food Canada, Agriculture Victoria (Australia), and the University of Melbourne, worked together to examine three feed supplements.
Methane inhibitor supplement 3-nitrooxypropanol (3NOP) could reduce costs and increase profits
3NOP is a promising commercial feed supplement that can be given to cattle to inhibit the enzyme methyl coenzyme M reductase – an enzyme responsible for creating methane in the animal's rumen (first stomach). After blocking the enzyme, 3NOP quickly breaks down in the animal's rumen to simple compounds that are already present in nature.
AAFC's Dr. Beauchemin studied the short- and long-term impacts of feeding 3NOP to beef cattle and shared her findings within the broader study.
"We now have clear evidence that 3NOP can have a long-term positive effect on reducing methane emissions and improving animal performance. We saw a 30-50% reduction in methane over a long period of time and a 3-5% improvement in feed efficiency," Beauchemin says.
Producing milk, gaining weight, and creating methane all take energy that a cow fuels by eating. Cattle eating a diet that contained the 3NOP supplement produced less methane. And, because there was less methane more energy could be used by the animal for growth. When using this supplement, cattle consumed less feed to gain a pound of body weight compared to control animals.
"What is also great is that the inhibitor worked just as effectively no matter what type of feed the cattle were eating," Beauchemin explains. "We don't know the actual market price of the supplement yet because it is still going through approvals for registration in Canada and the U.S. That will be important for farmers who want to calculate the cost-benefit of using 3NOP to reduce methane emissions from their cows and enhance profits."
The Story of Nitrate
Microorganisms in the cattle's rumen need nitrogen to be able to efficiently break down food for the animal to absorb. Nitrate is a form of non-protein nitrogen similar to that found in urea, a compound used in cattle diets. When nitrate is fed to cattle, it is converted to ammonia which is then used by the micro-organisms. During this process, nitrogen in the nitrate works like a powerful magnet that is able to hold onto and attract hydrogen. This leaves less hydrogen available in the rumen to attach to carbon to make methane, thus reducing the amount of methane produced.
Researchers in Canada found that adding nitrate to the diet of beef cattle reduces methane production by 20 percent in the short-term (up to three weeks), and after 16 weeks it still reduced methane up to 12 percent. In addition, feeding nitrate improved the gain-to-feed ratio. However, administering the correct dosage is extremely important, as too much nitrate can make an animal ill. So it is recommended this method should be used with care and caution.
Dr. Richard Eckard, a researcher from the University of Melbourne explained "I understand that in Canada, most forages are not that low in protein. But in the rangelands of northern Australia, the protein content in the forage is extremely low. It is possible that adding nitrate to Australian cattle feed may be able to improve the feeding regime from the current use of urea, but it depends on the price."
To supplement or not supplement with wheat, corn, or barley?
In the short term, wheat effectively reduced methane production by 35 percent compared with corn or barley grain; but, over time cattle were able to adapt to the change in feed and the methane inhibitory effect disappeared. Essentially, after 10 weeks, methane production was the same for corn, barley, and wheat.
The study also showed genetic variation in cows where about 50 percent of the cows that were fed wheat remained low in their methane emissions, even for as long as 16 weeks. However, the other cows adapted to the wheat diet and had methane emissions similar to, or even greater than those fed diets containing either corn or barley. Based on genetics, some cows are more adaptable than others and, in the long-term, it is more difficult to reduce the amount of methane they produce.
For dairy cows, Dr. Peter Moate, Dairy Researcher with Agriculture Victoria, was particularly intrigued about the link between milk fat, yield and methane emissions.
"We found that feeding cows wheat increased milk yield but fat levels decreased. For the farmer, it really depends on what they want to achieve in order to say whether this makes sense economically," explained Moate. "Overall, feeding wheat didn't have the long-term ability to reduce methane emissions, so it really couldn't be recommended as a best practice to achieve this type of goal."
"Our better understanding of feeding regimes will make a difference for farmers, but more importantly this research has really helped us understand more precisely the volume of greenhouse gases (GHGs) the industry is producing under different feed regimes. This is powerful information for policy makers," stated Beauchemin.
This is particularly true for countries that have implemented or are thinking about putting a price on carbon or a carbon trading scheme in place to reduce GHG emissions.
"By adopting different farming methods to reduce GHGs, farmers may be able to sell these "carbon credits" for revenue. But the key is to prove that these farming methods work and warrant being officially recognized for carbon credits. This work is one step closer in this process" explains Beauchemin.
While this project has wrapped-up, the work has not ended. Researchers in both countries unanimously agree that they will continue to help farmers and the industry find solutions to reducing their carbon footprint.
Scientists at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), working with the University of Arkansas and Glennoe Farms, hope this project, which brings together molecular biology, biogeochemistry, environmental sensing technologies, and machine learning, will revolutionize agriculture and create sustainable farming practices that benefit both the environment and farms.
If successful, they envision being able to reduce the need for chemical fertilizers and enhance soil carbon uptake, thus improving the long-term viability of the land, while at the same time increasing crop yields. For the full story, CLICK HERE.
"Water troughs appeared in our mathematical model as a place where water can get contaminated and a potential place where we could break the cycle," said Renata Ivanek, associate professor of epidemiology and the paper's senior author. The hypothesis was then tested in the field – with surprising results.
People commonly acquire infections from shiga toxin-producing E. coli through cow feces-contaminated beef and salad greens. The main shiga toxin-producing strain, E. coli 0157:H7, causes more than 63,000 illnesses per year and about 20 deaths, according to the Centers for Disease Control. Though cows carry and spread E. coli 0157:H7 when they defecate, the bacteria do not make them sick. For the full story, CLICK HERE.
Mitloehner is a professor and extension air quality specialist in the Department of Animal Science at the University of California, Davis. He is an expert on agricultural air quality, livestock housing and husbandry. Overall, he conducts research that is directly relevant to understanding and mitigating of air emissions from livestock operations, as well as the implications of these emissions for the health and safety of farm workers and neighboring communities.
"There is a lot of misinformation about how much animal agriculture actually contributes to the nation's greenhouse gas emissions and overall environmental impact," said Kay Johnson Smith, Alliance president and CEO. "With the industry's commitment to continuous improvement, Summit attendees will find Mitloehner's research enlightening and refreshing."
The University of Saskatchewan has been looking at the long term implications of using livestock manure to fertilize crops.
Dr. Jeff Schoenau, a professor with the University of Saskatchewan and the Saskatchewan Ministry of Agriculture Research Chair in Soil Nutrient Management, says typically only a portion of manure nutrients are available in the first year of application. For the full story, CLICK HERE.
The article reports the positive impact of long-term nutrient reductions on an important and valuable ecosystem in the Chesapeake Bay. Scientists indicate the resurgence of underwater grasses supports nutrient reductions from EPA's Total Maximum Daily Load (TMDL). This, along with conservation incentives, has resulted in a healthier Chesapeake Bay.
Jonathan Lefcheck, PhD, formerly of the Virginia Institute of Marine Science and now at the Bigelow Laboratory for Ocean Science, along with Gurbisz and 12 co-authors, shows that a 23 percent reduction of average nitrogen levels in the Bay and an eight percent reduction of average phosphorus levels have resulted in a four-fold increase in abundance of Submerged Aquatic Vegetation (SAV) in the Chesapeake Bay. This ecosystem recovery is an unprecedented event; based on the breadth of data available and a sophisticated data analysis, this is the biggest resurgence of underwater grasses ever recorded in the world.
The researchers employed advanced analytical tools to definitively show how the reduction of excess pollutants like nitrogen and phosphorus are the cause of this ecosystem recovery. To link land use and Chesapeake Bay status, researchers analyzed data in two different ways: one focusing on the cascade of nutrients from the land to the waterways, and one showing what happens to SAV once the nutrients are in the water.
Gurbisz said she participated in a series of workshops with scientists who study various aspects of SAV ecology. She said she helped develop the conceptual basis of the project and was excited that the work generated relevant results related to restoring the Chesapeake Bay.
The published findings are a collaborative effort between the following agencies: Virginia Institute of Marine Science, University of Maryland Center for Environmental Science, Environmental Protection Agency Chesapeake Bay Program, U.S. Geological Survey, National Socio-Environmental Synthesis Center, St. Mary's College of Maryland, Smithsonian Environmental Research Center, Maryland Department of Natural Resources, and Texas A&M University-Corpus Christi.
Through a four-year U.S. Department of Agriculture grant, Perkins and three colleagues will examine how producers' use of products to control parasites, known as parasiticides, has changed and how that has impacted the dung beetle population, soil quality and forage production. The National Institute of Food and Agriculture funding is part of the Bioenergy, Natural Resources and Environment Program, which focuses on the environmental sustainability of rangeland livestock production.
"Dung beetles are little drivers of ecosystem function," Perkins said. "They turn a big pile of dung into nutrients in the soil that can be taken up again by plants." Previous SDSU research looked at the biodiversity of dung beetles and other insects that populate dung pats. "We're adding onto that research and moving it all the way through to forage production," she explained.
Perkins, assistant professor. A. Joshua Leffler and professor Paul J. Johnson, an entomologist, will examine areas at the Ft. Pierre National Grasslands which are used by different livestock producers. Some producers use parasiticides to control parasites; others don't. "By conducting our research at Ft. Pierre, we are able to study areas that are adjacent to one another so the environmental variation among study areas is minimal," Perkins explained.
The researchers will measure the dung beetle population and examine how rapidly the dung is incorporated into the soil. They will measure nitrogen in the soil and plant production by weighing the biomass.
"Nitrogen availability is a key factor limiting forage production, and dung beetles are key organism in making nitrogen available to plants," Leffler explained. One doctoral student will also work on this portion of the project, with fieldwork beginning this summer.
However, what makes this project unique is collaboration with assistant sociology professor Jessica Ulrich-Schad. She will survey approximately 2,500 livestock producers to see whether they use parasiticides to control parasites in their livestock or not, whether that has changed over time and why. She will also ask how the parasiticides they are using have changed and what led to those changes. "Jessica is a critical member of our team. She helps us bridge the gap between the technical analyses and landowners and managers" said Perkins.
"We want to understand the drivers behind the use of these products," said Ulrich-Schad, who began exploring producer decision-making as a postdoctoral researcher at Purdue University. "We must get a better grasp of how farmers are making these decisions to know how we can encourage them to voluntarily use practices that are good for soil and water quality."
Through the survey, she will examine producers' awareness of how these parasiticides can impact dung beetle population, soil quality and forage production, as well as the roles that social networks play in the practices they use and the awareness they have. One doctoral student will work with Ulrich-Schad. Preliminary interviews with seven producers she characterized as innovators revealed that some are noticing a decrease in the dung beetle populations.
"When dung piles accumulate, fields become 'fouled'—livestock won't eat by the pile," Perkins explained. "We need the beetles to help break down the dung and keep the nutrients flowing and the plants growing." Research at other universities also shows that the presence of dung beetles can reduce the survival of parasite larvae in the dung pats.
Researchers at the University of Waterloo are developing technology to produce renewable natural gas from manure so it can be added to the existing energy supply system for heating homes and powering industries. That would eliminate particularly harmful gases released by naturally decomposing manure when it is spread on farm fields as fertilizer and partially replace fossil natural gas, a significant contributor to global warming.
"There are multiple ways we can benefit from this single approach," said David Simakov, a professor of chemical engineering at Waterloo. "The potential is huge."
Simakov said the technology could be viable with several kinds of manure, particularly cow and pig manure, as well as at landfill sites.
In addition to being used by industries and in homes, renewable natural gas could replace diesel fuel for trucks in the transportation sector, a major source of greenhouse gas emissions.
To test the concept, researchers built a computer model of an actual 2,000-head dairy farm in Ontario that collects manure and converts it into biogas in anaerobic digesters. Some of that biogas is already used to produce electricity by burning it in generators, reducing the environmental impact of manure while also yielding about 30 to 40 percent of its energy potential.
Researchers want to take those benefits a significant step further by upgrading, or converting, biogas from manure into renewable natural gas. That would involve mixing it with hydrogen, then running it through a catalytic converter. A chemical reaction in the converter would produce methane from carbon dioxide in the biogas.
Known as methanation, the process would require electricity to produce hydrogen, but that power could be generated on-site by renewable wind or solar systems, or taken from the electrical grid at times of low demand. The net result would be renewable natural gas that yields almost all of manure's energy potential and also efficiently stores electricity, but has only a fraction of the greenhouse gas impact of manure used as fertilizer.
"This is how we can make the transition from fossil-based energy to renewable energy using existing infrastructure, which is a tremendous advantage," said Simakov, who collaborates with fellow chemical engineering professor Michael Fowler.
The modelling study showed that a $5-million investment in a methanation system at the Ontario farm would, with government price subsidies for renewable natural gas, have about a five-year payback period.
A paper on modelling of a renewable natural gas generation facility at the Ontario farm, which also involved a post-doctoral researcher and several Waterloo students, was recently published in the International Journal of Energy Research.
The University of Saskatchewan has been conducting long term livestock manure application trials, in some cases on plots that have been studied for over 20 years, looking at the implications of using livestock manure at various rates with different application methods throughout Saskatchewan's major soil climatic zones.
Dr. Jeff Schoenau, a professor with the University of Saskatchewan and the Saskatchewan Ministry of Agriculture research chair in soil nutrient management, says the organic matter in manure, especially in solid manures, can directly benefit things like soil structure, water retention and so on.
"I think in terms of effect on the soil, especially with the solid manures where we're adding a fair bit of organic matter to the soil, we certainly see some beneficial effects show up there in terms of increased organic matter content, increased carbon storage. We see some positive benefits as well in water relations, things like infiltration," said Dr. Schoenau.
"We also need to be aware that manures also contain salts and so, particularly some manure that may be fairly high in for example sodium, we do need to keep an eye on the salt and sodium content of the soil where there's been repeated application of manure to soils where the drainage is poor. Generally what we've found is that the salts that are added as manure in soils that are well drained really don't create any kinds of issues. But we want to keep an eye on that in soils that aren't very well drained because those manures are adding some salts, for example sodium salts."
Dr. Schoenau says, when manure is applied at a rate that is in balance with what the crop needs and takes out over time, we have no issues in terms of spill over into the environment. He says that balance is very important, putting in what you're taking out over time.
What was done
Winter cereal rye planted as a cover crop has been shown effective in capturing nitrate before it leaches from the root zone. We conducted on-farm trials in central and southern Minnesota to determine if a rye cover crop would capture significant root-zone nitrate in the fall and spring but release it in time to maintain yield in the subsequent corn crop.
In the fall of 2015 and 2016, we partnered with 19 farmers (ten in 2015 and nine in 2016) to drill strips of cereal rye immediately after harvest of corn silage or soybean. After the rye was established and soil temperatures began to fall, we injected liquid dairy or swine manure into the cover crop and check strips. Three replications (with and without cover crop) were planted as wide or wider than the farmer's combine or silage chopper. The following spring, we sampled the cover crop for biomass and nitrogen content. We also soil sampled the cover crop and check strips to a 24-inch depth for nitrate. The rye was terminated, usually before reaching eight inches in height. In most cases, the rye was terminated with herbicide and tilled in. Corn was planted in the cover crop and check strips, usually with a small amount of starter nitrogen. We measured yield and nitrogen content of the corn at harvest.
Fall manure injection into cereal rye cover crop.
Fall manure injection into cereal rye cover crop.
Cereal rye at same location two weeks after manure injection
Cereal rye at same location two weeks after manure injection
Spring rye growth at the same site.
Spring rye growth at the same site.
Our results indicated
Spring Soil 24 inch Nitrate. Cover crop had 124 pounds of nitrate nitrogen per acre. No cover crop had 202 pounds of nitrate nitrogen per acre. The difference was 78 pounds of nitrate nitrogen per acre.
In both years, adequate growing season existed to establish the rye cover crop after either corn silage or soybean harvest, but above-ground fall growth was limited.
The rye was very resilient to manure injection, however, stand reduction was considerable at two sites where shank injectors or disk coverers were too aggressive.
Spring rye growth was good at most sites, with soil nitrate reduced under the cover crop compared to the check strips at all sites.
Rye growth and nitrogen uptake were greater in southern than central Minnesota.
Across sites, there was no significant difference in silage or grain yield between the cover crop and check strips.
Grain yield adjusted to 15 percent moisture. Cover crop yielded 199.5 bushels per acre whereas no cover crop yielded 201.2 bushels per acre.
Corn silage yield adjusted to 65 percent moisture. Cover crop yielded 20.7 tons per acre whereas no cover crop yielded 20.8 tons per acre.
Take home message
We concluded that, in central and southern Minnesota, it is feasible to establish cereal rye cover crop after corn silage or soybean harvest, inject liquid manure, capture root-zone nitrate with the rye, and deliver sufficient nitrogen to the subsequent corn crop.
Additional experiments are needed to determine any nitrogen recovery effect of no-till vs tillage termination, as well as supplemental nitrogen needs if the rye were terminated at a later maturity.
Authors: Les Everett, University of Minnesota Water Resources Center and Randy Pepin, University of Minnesota Extension
Reviewer: Melissa Wilson, University of Minnesota and Mary Berg, North Dakota State University
As part of research being conducted on behalf of Swine Innovation Porc, Canadian scientists are developing a precision feeding system that will tailor the ration to match the nutritional needs of each individual pig.
Dr. Candido Pomar, a research scientist with Agriculture and Agri-Food Canada, says by supplying one diet that meet the needs of the least productive pigs, the producer ends up overfeeding the more productive pigs.
“We have to look at nutrient requirements from two different points of view,” says Dr. Pomar. “One is when we are looking to a given animal or when we are feeding a group of animals the definition of nutrient requirements is very different. Feeding one pig at a given time is not the same thing as feeding a large group of pigs during a long period of time. We have to understand that estimating nutrient requirements, we are addressing the issue of one animal, why are we using that to feed groups of animals?”
“When you over supply the nutrients, you are using important resources that finally ends in manure so this is very expensive,” he adds. “Today the farmers are challenged to reduce feeding costs.”
“Feed costs represent 60 to 70 percent of the cost of producing a hog. So optimizing the level of nutrients, knowing how much the pigs need we can reduce costs. Reducing costs, we are [also] reducing the environmental impact because all the nutrients they giving in excess finish always in the same way, in manure.”
Dr. Pomar says early indications are that by personalizing formulations for each pig, we can produce the same amount of meat with 25 percent less protein, dramatically reducing feed costs.
Greenhouse gases contribute to the warming of our atmosphere. Carbon dioxide gets the most attention because so much is released as we burn fossil fuels. Nitrous oxide (yes, the “laughing gas” the dentist may give you) is also a powerful greenhouse gas. There isn’t nearly as much of it in our atmosphere as carbon dioxide: it makes up only about five percent of the greenhouse gases, compared to 82 percent for carbon dioxide. However, it is a much more potent greenhouse gas, with a global warming potential nearly 300 times greater than carbon dioxide.
About 40 percent of all nitrous oxide emissions come from human activities, and agriculture is by far the greatest source. About 90 percent of that contribution comes from soil and nutrient management practices like tilling and fertilizing. This means that changes in these practices have great potential to reduce nitrous oxide emissions from agriculture. But there is also the potential to make them worse.
That’s where manure injection comes into the story. Animal manure has been used as a fertilizer for thousands of years. It is an excellent source of nutrients for plants and helps build good soil. Manure slowly releases nitrogen, one of the primary elements that help plants grow. Because of this slow release, it does not have to be applied as often as commercial fertilizer.
Traditionally, manure has been spread, or broadcast, onto the fields. However, with changing weather patterns some areas have had heavier rains and more flooding. Many farmers are taking steps to avoid manure runoff that can affect the quality of lakes and streams nearby. One such step is manure injection, a relatively new way of applying manure. It helps keep the manure on the crops and on the fields. Manure injectors insert narrow troughs of liquid manure six to eight inches deep into the soil.
“Unfortunately, at that depth conditions are just right for producing nitrous oxide,” said Adair.
The soils are often wet and there is little oxygen. This leads microbes in the soil to change the way they convert organic matter into energy. This alternative process changes nitrogen into nitrous oxide as a byproduct.
Adair and her colleagues have been studying the potential of tillage and manure application methods to reduce nitrous oxide emissions. They are comparing conventional tilling versus no-till systems, and broadcast versus manure injection.
Through several farm and laboratory experiments, they have found the tillage method has little impact on nitrous oxide emissions. However, manure injection significantly increases nitrous oxide emissions compared to the broadcast method. This is especially true soon after injection. Warming soil in the spring and more winter thaw/freeze cycles in winters also seem to increase emissions. And when warmer winters are combined with manure injection, this multiplies the effect, leading to even more nitrous oxide emissions.
Adair says ongoing research may show the cause of winter and spring emissions and whether there are steps that can reduce them. Perhaps cover crops grown between main-crop seasons will be able to reduce wintertime nitrous oxide emissions. And perhaps the timing of manure injection is important.
“Injecting during dry periods seem to reduce emissions, and it may be that fall injection results in smaller emission pulses, but we don’t have enough evidence of the latter yet,” Adair explains. “Our work continues so we can find better answers for growers, and protect the environment.”
Adair presented this research at the October Annual Meeting of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America in Tampa, FL.
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International Symposium on Animal Mortality ManagementSun Jun 03, 2018 @ 8:00AM - 05:00PM
2018 World Pork ExpoWed Jun 06, 2018 @ 8:00AM - 05:00PM
Anaerobic Digester Operator Training – WisconsinTue Jun 19, 2018 @ 8:00AM - 05:00PM
2018 North American Manure ExpoWed Aug 15, 2018 @ 8:00AM - 05:00PM
2018 Canada's Outdoor Farm ShowTue Sep 11, 2018 @ 8:00AM - 05:00PM
Farm Science Review 2018Tue Sep 18, 2018 @ 8:00AM - 05:00PM