Animal agriculture often endures criticism from our neighbors and consumers relative to sustainability. But when it comes to management of carbon and nutrients, animal agriculture has a positive story to share.  Many environmental and sustainability organizations promote the importance of a “circular economy” for increasing sustainability.  Farmers should help our neighbors and consumers recognize agriculture’s long term practice of implementing this circular economy. This article will help you understand and share information about agriculture’s circular economy for nitrogen (N), phosphorus (P), carbon (C), and other nutrients as well as the Nebraska Advantage for sustainability.

The Circular Economy

Many environmental organizations, businesses, and governmental organizations champion the benefits of the circular economy for improving sustainability (World Economic Forum discussion of circular economy is one of many web discussions on this topic).  The circular economy is in contrast to our traditional linear approach to production of most products (Figure 1).  Our linear economy assumes that the source of raw materials in unlimited and that there will be a safe environment in which one can store our manufactured products once they reach an end to their useful life.

The linear economy places some difficult burdens on our children and grand-children. For example, the growing Nebraska “mountain” of landfilled products on the north side of Lincoln is one monument to our linear economy. The linear economy is also plagued by leaks into the environment and unintended consequences for current and future generations to manage. A circular economy focuses on reuse of products (e.g. newspapers recycled into paper) as a preference over extracting new resources (e.g. fossil fuels) and as a system that minimizes leaks of resources into the environment.

Animal Agriculture’s Circular Economy

Integration of animal and crop production represents an excellent example of the application of the circular economy to manage N, P, C and other nutrients (Figure 2).  Agriculture recycles these critical nutrients from animal feed to animal proteins to manure to soils and back to animal feed. Nutrients are added to the farm when animals, feed and fertilizer are purchased (purple input arrow).  These inputs must offset the nutrients leaving the farm as meat and milk (purple output arrow) as well as any nutrient losses in the system (e.g. nitrogen lost into the air or feeds that spoil).  

Our circular economy for agriculture has become more complex over the last several decades (Figure 3).  Animal feeding operations (AFOs) purchasing of feeds from off-farm sources and agriculture’s diversion of corn into energy production are two examples of those increased complexities. Agriculture’s circular economy for nutrients has required establishing new recycling loops for ethanol by-products and manure nutrients transferred to neighboring crop farms to be established. Additionally, cattle and pigs have historically been an important means of recycling wastes of many food industries, thus diverting those products from landfills to meat and milk production.  Whether recycling of nutrients is completed within a single business or involves multiple businesses, this circular agricultural economy for N, P, and C is an environmentally sound approach, typically advanced in many ways beyond that implemented by most non-agricultural industries. 

Telling Agriculture’s Sustainability Story

Here are a few important messages to share with your neighbors and consumers about agriculture’s circular economy.

• Modern agriculture systems recycle nitrogen, phosphorus, carbon, and other nutrients in a continuous loop involving animal feeds, animals, manure, and soil, an excellent example of a circular economy as opposed to a more traditional linear economy (e.g. petroleum fuels used in our transportation).
• If agriculture is growing corn and other feeds locally, then growing animals in proximity to these feeds is essential to maintaining this circular economy.  Local decisions to allow corn production but reject animal production reduces the environmental sustainability of our agricultural economy (i.e. less opportunity to recycle N, P, and C).
• Manure and its integration into our soils and crop fertility programs is an important part of the circular management of nutrients. Manure improves the soils health and productivity by recycling manure carbon, reduces the mining of phosphorus (a nutrient with a limited supply) by recycling manure P, and reduces the need for converting natural gas to nitrogen fertilizers (a source of greenhouse gas emissions) by recycling manure N.
• In recent decades, animal agriculture has adapted its circular economy to:
  • recycle waste products from many food processing industries into animal proteins;
  • recycle waste products from the ethanol industry into animal proteins; and
  • recycle animal manures both inside our AFOs and with our neighboring crop farms.
  • For the animal proteins sold to our consumers, how are they re-cycling those nutrients back into a circular economy?  Or are consumer’s waste products destined for a waste treatment plant or landfill? Some communities ask agriculture to recycle its treated bio-solids as opposed to land filling these products, another contribution to a circular economy. 

Assessing Your Own Circular Economy

In recent decades, our animal feeding industry was reminded that our circular economy produced some significant leaks of manure N and P (resulting in environmental regulation of many AFOs). The past decade has demonstrated the ability of many AFOs to improve their performance by utilizing these nutrients more efficiently in cropping systems.  At the same time we should be sharing our story of our circular agricultural economy, we should also be asking how well our agricultural enterprise is recycling carbon and nutrients and minimizing the leaks (See Figure 4). 

These six questions are a good starting point for assessing an agricultural operation for its strengths as a sound circular economy.  Does my animal feeding operation:

____   Accurately credit both manure nitrogen and phosphorus in the crop’s fertility programs?

____   Target fields that benefit the most from improved soil health (or function) resulting from the carbon in manure?

____    Conserve nitrogen in the storage of manure?

____   Plug leaks in manured fields by minimizing soil erosion, runoff, and leaching?

____   Market manure to neighboring crop farms when purchasing significant amounts of animal feeds? The amount of P in transferred manure should be roughly equal to the amount of P in purchased feeds.

____   Train employees on the practices critical to efficiently recycling carbon and nutrients?

If you answered “Yes” to any of these questions, these are great personal stories to share with your neighbors of your contribution to the circular agricultural economy.  If your answers identify potential concerns, then you have the opportunity for “continuous improvement”, a future opportunity for improving sustainability.

Managing recycling of P is generally doable.  Managing N and C is much more challenging. N and C flows are fraught with leaks, even in the best managed agricultural enterprises. However, agriculture’s environmental legacy will be defined in large part by our ability to recycle these three compounds. Investing in the management skills and tools necessary to recycle these efficiently will produce some economic return and significant environmental benefit.

I might conclude this discussion by asking the question “Should Nebraska be exporting animal feeds grown locally to Texas, North Carolina, or China?  Those nutrients rarely get recycled.  Or should we grow the pigs, chickens, and cattle in Nebraska and export animal proteins?”  The Nebraska Advantage for integration of crop production, animal production, ethanol production, and food processing in close proximity is a foundation for a sustainable circular agricultural economy, an important story that we should all be sharing. Our Nebraska Advantage is a story worth telling.

Reviewers: Larry Howard, Nebraska Extension Educator and Jim McDonald, Professor of Animal Science, University of Nebraska-Lincoln


Interviews with the authors of BeefWatch newsletter articles become available throughout the month of publication and are accessible at https://go.unl.edu/podcast.