Manure Manager

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Integrated planning for optimal manure disbursement

Manureshed research can help with placement of future livestock operations.


October 12, 2021
By Ronda Payne

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Application of swine manure is expected to be most efficient when close to the animal source. Photo courtesy of Robb Meinen

North Americans might be eating more plant-based foods, but meat products will continue to be a staple of everyday diets. The required growth in livestock production to meet this future demand for domestic and export meat products brings with it a corresponding growth in manure produced.

 Statistics help tell the story. The per capita American meat consumption in 2020 was 225 pounds according to Statista. UN World Population Prospects indicates the North American population is expected to grow by approximately 14.5 percent from 2020 to 2050. Even if plant-based diets continue to increase in acceptance, there will still be an increased demand for livestock operations and thus the need for necessary improvements for optimal manure use and environmental health.

 Dealing with manure is a farm operator’s issue. However, it is also a regional, national, international and global issue. Robb Meinen, senior extension associate with Penn State’s department of animal science has been part of a team of experts exploring how better management of manuresheds can improve the distribution of nutrients naturally occurring in livestock production. 

 “A simple definition of a manureshed starts with any location where manure nutrients are generated,” he explains. “In much of our work we have utilized country-level analysis to consider trends in manuresheds, which is because much of the data used to assess manuresheds are available on a country basis.”

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 Despite this country-level data, manuresheds themselves are made up of regions known as source areas where the manure nutrients are produced and sink areas are those where manure nutrients can benefit crops. Meinen says this can be applied at a range of scales from farm-level to regional and beyond. So, at its simplest, a laying hen operation would be seen as a source area while a sweet corn and pumpkin farm could be a sink area. Thus, the manureshed is the available manure from the laying hen farm and the total area of crops it can provide adequate nutrients to within economical transportation confines. 

 Exploring the most efficient balance of nutrients and distribution is the purpose of the study. This isn’t a light task when one considers: the number of livestock operations, the amount of manure produced, the volume of nutrients from those various types of operations, the demands of crop growth and the economical and viable transportation of the nutrients. This data then needs to be combined with the expected growth in livestock operations and whether there are enough manureshed sinks to take up the additional nutrients within the efficient transportation radius. 

 “Both nitrogen and phosphorus can be considered in the manureshed discussion. Once that nutrient supply is defined based on items such as species of animal, number of animals and expected nutrient output per animal, we can estimate how much cropland area is needed to assimilate those nutrients,” he says. “This idea is not very different than typical nutrient management planning and considers crop types and production that is typical in the area where the manure is produced.”

 It takes a great deal of expertise to consider these ins and outs and the team Meinen is part of brings together international minds. 

 “There are over 70 scientists involved across a wide range of disciplines. The work is part of the USDA Long-Term Agroecosystem Research (LTAR) Network focusing on manuresheds,” he says. “Most team members work for the USDA-ARS, but a number of specialists from universities and Agriculture and Agri-Food Canada have been invited to provide expertise.”

 He notes that these team members, who had their first meeting in February 2020, bring everything to the table from data analysis and nutrient cycling to manure management and water quality expertise. There are also experts in agronomy, animal industry, animal nutrition, soil, greenhouse gases, social ecology and more. With that kind of diversity it would seem there would be nothing to surprise them, but he says, there can be. 

 “I really like that if the group cannot answer a question, then they invite a scientist that has specific expertise to explore that question,” he says. “It’s a large exercise to consider many aspects of manure nutrient distribution, but ultimately stakeholders… have to work together to implement the changes that the manureshed project will highlight.”

 An example of this is in the manuscript on which he is the lead author. It highlights that the growth of the swine industry may lead to locating hog farms in sink areas due to the low nutrient, high liquid nature of swine manure and its transportation inefficiencies. Alternatively, poultry manure with its drier texture and high nutrients can be moved efficiently to crop sink areas without a relocation of animals. 

 Producers may wonder how a vast think-tank and studies like this can benefit their operation and, in the short term, Meinen notes there may not be extensive impacts. However, when these same operations add additional animals or new livestock operations open up down the road, manureshed analysis can assist with the surplus nutrients in terms of balanced distribution. 

 “Someone’s nutrients are most likely going to have to move to lands that can act as a nutrient sink,” he explains. “There are countless scenarios here, but it means a change for someone in the neighbourhood can be expected. Manure redistribution to new lands is likely and chances are the manure nutrients can replace historic fertilizer nutrient application.” 

 Therefore, wise regional planning will encourage new swine operations to locate in manureshed sinks rather than in areas where there are already other hog farms that are fulfilling the immediate nutrient needs of the area. Additionally, he suggests that smart expansion can be an integrated approach that includes placement of feed mills in regions with crop farmers (manureshed sinks) and potential sites for livestock operations.

 “It’s a big picture idea that could be supported by agencies and integrators, but I allow that it requires very strategic economic planning,” he says. 

 He explains that in areas where swine and poultry operations co-exist, there can be complications with how the nutrients are moved from source regions to sink regions. These are important considerations as the animal agriculture industries expand. Do animal commodity associations and other regulatory bodies have the right to work with municipalities to help determine placement of new livestock operations? What could this type of smart growth look like? 

 “I don’t think it is possible to find a one-size-fits-all solution,” he says. “Expanding manuresheds might make sense, for example with the poultry broiler industry because it may make logistical sense to have animals close to the harvest plant and broker manure to distant lands where the nutrients are needed.

On the other hand, relocating animals to a nutrient sink area also relocates associated manure nutrients to that area where the N and P resources are needed.”

 There are also animal health benefits to be had. With swine manure’s limited transportation efficiencies, hog farms can have greater isolation from one another as currently seen in parts of Pennsylvania.

 “Such isolation limits risk of disease transfer, which in turn positively impacts animal welfare, farm efficiencies and profitability,” he says. “Another important consideration is whether the producer at the new contracted location has a need for the manure nutrients produced at the farm. Manure nutrients enhance profitability of the farm’s cropping operations by replacing costs of commercial fertilizer and positively influencing soil health.”

 Meinen says the heart of the issue is water quality. 

 “All of the farm-by-farm work with nutrient management planning that we do across the nation does a good job of distributing nutrients properly on a local level, but we know that improvements can still be made,” he says. “Some local areas already have more manure nutrients than local cropland can assimilate in the long-term.”

 Similar to how fossil fuel companies have started to take part in alternative energy options like Shell’s electric vehicle charging, he would like to see fertilizer companies take part in nutrient distribution solutions. 

 “It’s a complicated puzzle for sure,” he says. “Some areas will always be better suited for animal production and other areas better suited for crop production, especially with existing infrastructure. It is long understood that cycling manure nutrients back to cropping areas in lieu of introducing fertilizer nutrients into those areas is the ultimate solution to many of our water quality issues associated with agriculture.” •