Module III Section C Animals in the agro-ecosystem
Section C: Animals in the agro-ecosystem
- Projected Outcomes
- Background / Lessons
- Introduction
- Ecological question 1: What are the nutrient flows in the system?
- Ecological question 2: What are the sources and sinks of pollutants in the system?
- Ecological question 3: What are the interactions of living organisms in the system?
- Ecological question 4: What are the energy flows in the system?
- Conclusion
- Activities
- Presentation
- Career Pathway content standards
Projected outcomes:
- Students will learn how to apply ecological analysis to animal production systems.
Background /Lessons:
Introduction
“Mother earth never attempts to farm without live stock…”
Sir Albert Howard, An Agricultural Testament, Oxford University Press, 1940, p. 4.
Animal agriculture can have very negative ecosystem impacts, or it can bring ecosystem benefits. In general, when animals are raised in large confinement systems and fed grain, their production uses more energy and causes more pollution than the production of field crops. When animals are raised in small groups primarily on pasture, their production uses less energy and tends to cause less pollution than field crop production. However, good management is the key in all cases. Well-managed confinement systems can minimize environmental damage, and poorly managed grazing can cause serious environmental problems.
In sustainable agriculture the goal is to take advantage of ecosystem processes by designing an agricultural system that works with them.
As we look at the agroecology of animal production, we should keep four questions in mind:
- Where do key nutrients come from?
- What are the sources and sinks of pollutants in this system?
- How do the living organisms in the system interact?
- What are the energy flows?
Ecological question 1: What are the nutrient flows in the system?
In a sustainable system they will be recycled on-site or generated in a renewable fashion.
When livestock feed is obtained from off the farm, it is extremely difficult to close nutrient cycles, especially for phosphorus, potassium, and carbon. These nutrients are being exported from the farms producing the feed, and they accumulate on the livestock farms in the form of manure, creating nutrient imbalances in both locations.
When the livestock feed comes from the same farm or from farms within a few miles, the nutrient cycles for these major nutrients can be nearly closed, because it is cost-effective to return the nutrients in the manure to the fields where the feed is grown. Nutrient losses from export of the nutrients contained in the animals are minor compared to the nutrient value of the manure. Moreover, good manure management can minimize leaching and runoff of nutrients in manure.
Water is not typically thought of as a nutrient, but when livestock feed is grown using irrigation, that disrupts the natural hydrological cycle, which can have far-ranging ecological impacts. Much of the forage and grain fed to beef produced in the west is grown using irrigation. Some of this irrigation water is pumped from aquifers at unsustainable rates. Some is diverted from river systems, altering aquatic communities, and reducing the water available for other uses. For example, about 80% of the water taken from the Colorado River in California, Arizona, and Nevada is used for agricultural purposes. Long before the Colorado River reaches its historic outlet to the ocean in Mexico, it has completely dried up. Some of the water withdrawn goes to fruit and vegetable production, but livestock production is also a major water user (see history of the Colorado River Crisis here).
In Iowa and Wisconsin production of livestock feed and forage generally does not require irrigation. In both these states, the withdrawal of irrigation water from streams and rivers is regulated to protect aquatic life. However, even in this area the potential exists for local conflicts over agricultural water use.
Sustainable nutrient management practices:
- Managed grazing allows animals to consume plant nutrients right where they are produced and return most of those nutrients to the pasture soil in the form of manure (without additional capital, labor, and energy costs for storage and spreading).
- Mixed species pastures contain legumes that support nitrogen-fixing bacteria, reducing or eliminating the need for N inputs from off-site.
- Year-round ground cover on well-managed pastures tends to retain soil nutrients on-site.
- Many high-quality forage crops are legumes that support nitrogen-fixing bacteria (See New Mexico State Article, here).
- Proper manure management minimizes nutrient runoff, leaching, and volatilization as well as unpleasant odors. It also returns nutrients to the fields where they are needed for optimum plant growth. More in-depth publications about manure management are available at Nutrient Management – Integrated Pest and Crop Management – UW–Madison (wisc.edu), including When and Where to Apply Manure.
- Composting is a form of manure management that stabilizes nutrients, can reduce weed seed viability and disease pressure (See composting’s effect on soil health, here).
- Deep bedded systems absorb nutrient-rich urine as well as manure solids and lend themselves to composting.
- With the help of the NRCS, this Minnesota Dairy was able to get assistance in creating a more sustainable and productive liquid manure storage system. This system prevents leeching to water systems and is used to keep the nutrient cycle within the farm (See here).
- A huge issue when it comes to manure is greenhouse gas emissions. Liquid and slurry manure generate methane (CH4), which is a potent greenhouse gas. All manure can produce nitrous oxide (N2O), an even more potent greenhouse gas. Methane emissions from manure management are rising rapidly in Wisconsin and across the US, even as most other agricultural greenhouse gas emissions are stable or declining.
Ecological question 2: What are the sources and sinks of pollutants in the system?
A sustainable system will minimize pollution.
In livestock production systems, animal waste or manure is a major potential source of pollution. Other pollution sources from livestock production can include erosion from poorly managed grazing or cropland used to raise feed, improper disposal of dead animals, improper disposal of milkroom waste, and dust and odors from CAFOs (Confined Animal Feeding Operations). Enteric emissions from ruminant digestion add a significant amount of methane to the atmosphere.
Beef and dairy production cause significant pollution. Cattle either spend all their lives, or most of their lives on pastures. After 6-8 months on pasture, most commercial cattle finish their growth prior to slaughter on feedlots where animals are kept in a confined area and are fed grains. The best system for beef and dairy production is hotly debated. Grain based feed offers advantages of faster growth rates and less land demand per unit of meat when compared to fully grass finished beef. Both conventional and grass-finished livestock systems can contribute to deforestation, habitat destruction, nutrient runoff, and erosion when they are not properly managed. While CAFOs finish cattle more efficiently than pasture, the local environmental impacts of well-managed feedlots and grain production are more severe than those of well-managed pasture. With well-managed rotational grazing and silvopasture, beef and dairy production can minimize pollutants, build soil carbon, and restore landscapes. At the end of the day, all cattle operations share the same issue, large methane emissions (Penn State article discussing grass vs. grain in cattle production can be accessed here). (Video on the debate about meat and climate)
Francis Thicke has been exploring regenerative agriculture systems to promote land restoration, soul quality, and healthier milk at his organic Dairy operation in Iowa, this can be accessed here.
While regenerative practices can have beneficial effects on the land, they are a more labor and land intensive production system for cattle. Reasons like that are why pasture raised and grass-finished products can be sold at a premium. Farmers logically want to maximize their profits and it’s often more profitable to finish beef on grain and is less labor intensive than moving cattle from paddock to paddock as seen in rotational grazing systems. Can a pasture system or agroforestry system meet today’s commercial demand for beef and dairy? Will consumers be willing to pay more for these products? Will future environmental issues cause more regulation on the types of beef and dairy operations farmers utilize?
The crop production we use to feed livestock can also be a source of pollutants in agriculture. Since most field crops in Wisconsin and Iowa are used for animal feed, the pollution that may result from field crop production, including erosion and runoff and leaching of fertilizers and pesticides, can be viewed as an indirect result of livestock production.
Manure is a valuable farm resource if it is properly managed and has potential to be a source of valuable nutrients in crop production. However, when livestock is raised or finished far from where their feed is grown, it is usually not economical for the farmer to apply the manure only as needed for optimum crop growth. Moving manure is expensive and time-consuming, which can lead farmers to over-apply it on fields that are close to livestock facilities. Too much manure is a major agricultural pollutant and puts watersheds at risk for contamination. For example, according to the Wisconsin Department of Natural Resources, improper manure management leads to the death of many aquatic species and destruction of river, pond, lake, and wetland habitats (See here). In addition to harming aquatic life, microorganisms from livestock manure can threaten human health if they get into the water supply. Areas in Iowa that have seen the consequences of water use and the dangers of runoff are working on solutions to the issue (Video access here).
Sustainable practices to minimize pollution
- Livestock production should be sited close enough to the area of feed production for the return of manure to those fields to be profitable.
- Grazing should be managed to prevent soil erosion and degradation of stream and riverbanks. Both rotational grazing and traditional extensive grazing can minimize pollution, if well-managed.
- Manure must be stored, handled, and applied in such a way that it will not leach or run off and contaminate surface or ground water. Deep bedding and composting are manure management practices used by many sustainable livestock producers. Manure Storage, NDSU Composting Guide.
- Video and Website guide, here.
Wetlands as a Bioremediation device
Much of the once vibrant and thriving wetland system of the Midwest has been converted to agricultural and urban developments. Wetlands serve as a habitat for countless flora and fauna species and act as the land’s natural filtration system. Much of the wetland habitat in the Midwest has been destroyed by agricultural development. In fact, the Wisconsin DNR estimates that just 47% of the state’s wetlands remain from what they once were, and even this number is thought to be a conservative estimate. Drainage ditches, irrigation systems, and tiling of crop fields have altered the landscape, decreased biodiversity, and have increased harmful agricultural runoff. Destruction of wetlands has contributed to algal blooms commonly seen throughout the Midwest, as well as contamination of drinking water.
In recent years there has been interest in constructing bioremediation wetlands to help agricultural operations filter synthetic fertilizers and manure. Bioremediation is the process of using biological systems and organisms to break down environmental pollutants. Constructed wetlands are artificial aquascapes that use wetland plants to filter runoff by absorbing excess nutrients such as phosphorus and nitrogen. These kinds of wetlands are being used by farmers to collect excess nutrient runoff from fields and protect watersheds from their livestock manure. By constructing small wetland areas to match up with the size of the operation, farmers can significantly reduce their runoff and improve surrounding water quality. The Nature Conservancy has been making efforts to teach farmers about the importance and benefits of wetlands and help them get resources to create wetlands on their operations (See here).
How Artificial Wetlands are constructed: Minnesota NRCS Wetland Initiative
Wisconsin wetlands: acreage facts | | Wisconsin DNR
Ecological question 3: What are the interactions of living organisms in the system?
Typically, sustainable agro-ecosystems will try to work with species interactions and will favor species diversity.
Grazing systems are based on direct species interactions. When livestock is raised in confinement, natural ecological interactions are interrupted. Feed crops are raised in a monoculture, then harvested, transported, stored, and fed to livestock held in areas where all other living species except human workers are excluded as much as possible. The species interactions on pastures can bring additional challenges such as loss to predators and exposure to parasites. However, they also bring ecosystem services, such as nutrient cycling, pest management, and efficient capture and storage of solar energy.
Rotationally managed pastures use of native species can provide habitat for wildlife and native prairie plants:
- Rotational Cattle Grazing to Restore Degraded Chihuahuan Desert Grasslands and Promote Watershed Health | Pitchstone Waters – Texas
- See How bison are being utilized to help restore this Minnesota Prairie before going into meat processing, here.
Another issue to consider is the genetic diversity of the farm animals themselves. For thousands of years, localized selection of traits in farm animals led to a proliferation of regional breeds. For example, in England, a country smaller than the state of Wisconsin, there are more than 25 breeds of sheep, most developed in and named for an area no bigger than a US county. These breeds varied widely in their adaptations and the characteristics of their meat and wool. (For a listing of recognized sheep breeds worldwide, see the left panel at http://www.ansi.okstate.edu/breeds/sheep/). Modern commodity livestock production and processing emphasizes uniformity and a few traits such as leanness and efficiency of growth. This emphasis has led to having one or two breeds dominate production agriculture for our entire country and beyond. Perhaps the most extreme example is the domestic turkey. All turkey meat raised by large commercial growers in the US is from one breed, the Broad-breasted White. This turkey has been bred to put on weight fast, to have white feathers that leave the skin a uniform creamy color, and to grow a large amount of breast meat. In fact the breasts of mature birds are so large that these animals cannot mate naturally. Because of this, all commercial turkeys in the US are bred using artificial insemination. Recently, some specialty producers have begun to grow and market some of the more than 20 other American breeds with different size and flavor characteristics and better abilities to fend for themselves. See Top 9 Turkey Breeds Found on Farms Across the United States. Genetic traits, from disease resistance and adaptation to a variety of climates to variations in flavor and other traits of interest to the consumer or farmer. Organizations such as the American Livestock Breeds Conservancy are now working to preserve rare breeds of farm animals in our country. (See Endangered Livestock list here).
Manure management can have a significant effect on soil organisms. Raw manure contains pathogens that can threaten human health until they are broken down or consumed by benign organisms. The nutrients and organic matter in manure can benefit soil life. Compost contains a variety of generally beneficial soil organisms, though the predominant organisms will vary, depending on the materials and process used.
What are the impacts on other organisms of feed production? For example, in aquaculture systems high-value carnivorous fish such as trout and salmon are often fed fish meal. Production of this fish meal may damage marine ecosystems. At the other end of the process, pollution from livestock production, such as sedimentation and nutrient runoff, can damage aquatic ecosystems.
In some cases, the livestock may transmit disease or may escape and displace native species. For example, farm animals such as pigs, goats, dogs, and cats have contributed to the extinction of many flightless birds on islands in the Pacific Ocean. In Wisconsin there is debate about whether deer farms may have introduced Chronic Wasting Disease to the state’s wild whitetail population (DATCP Home Chronic Wasting Disease (wi.gov)).
Sustainable practices include:
- Grazing on multi-species pasture (Add Diversity to Your Pastures with Multispecies Grazing – Cornell Small Farms).
- Managing grazing and haying to encourage nesting success for grassland birds such as meadowlarks, grasshopper sparrows, and bobolinks (see Grazing Like It’s 1799: How Ranchers Can Bring Back Grassland Birds | Audubon).
- Grazing different livestock species together or in sequence.
- Use of traditional breeds adapted to the climate and to outdoor conditions.
- Providing shade and/or shelterbelts.
- Management of water access to protect streams and prevent erosion (see Grazing streamside pastures).
Ecological question 4: What are the energy flows in the system?
Sustainable agro-ecosystems rely more on solar energy than on fossil fuels. Sustainable systems minimize energy waste.
In general, grazing systems maximize use of solar energy and minimize use of fossil fuels. Unlike in confinement animal production systems, no fossil fuels are used to harvest, dry, or transport the feed to the grazing animals when forage growth is good. Also, energy use for extracting, transporting, and applying fertilizer to well-managed pastures is minimal. Confinement systems such as hoophouses that rely on natural ventilation and on deep bedding for manure management require less energy for both construction and operation than fully confined systems with mechanical ventilation and liquid manure management systems. On the other hand, manure from confinement systems can be used to generate electricity through biogas collection(California Farmer Example), though it is not clear whether the energy recovered compensates for the extra energy required for the confinement system.
Sustainable energy management practices:
- Rotational grazing
- Grazing of cover crops
- Stockpiling of winter forage on pastures minimizes energy used for manure spreading
- Design buildings to eliminate or minimize reliance on mechanical ventilation, heating, and cooling
- If animals are in confinement, consider generating electricity from manure
- Install and maintain energy efficient systems for major energy users such as refrigeration of milk (see Introduction to Energy Efficiency and Conservation on the Farm – Farm Energy (extension.org)).
More than half of the energy in our food system is used not on the farm, but in transportation, processing, storage and packaging, and home cooking.
Sustainable practices for the consumer:
- Buy local foods, when possible
- Avoid excess packaging
- Use energy-efficient appliances and techniques when possible
- Use renewable energy sources, if possible (solar and wind power)
- Consider eating lower on the food chain or sticking to grass-fed meat and dairy products (most of the food energy contained in grain is used by livestock to sustain their own life and only a small amount is stored as meat. Thus it takes 4 lbs of corn to produce 1 lb of pork and 7 to 10 lbs of corn to produce 1 lb of beef, 2 lbs of corn for 1 lb of chicken, and 1-2 lbs of fishmeal for 1 lb of tilapia).
Conclusion
Poorly managed animal agriculture can have extremely negative impacts on the environment and can be very wasteful of natural resources. However, animals play critical roles in natural eco-systems, and animal agriculture that mimics and builds on natural systems can be far less damaging to the environment than even well-managed cropping systems that try to function without animals.
In the several decades, ideas about grazing have changed considerably, as the use of lightweight electric fencing allowed much more flexible and detailed management of livestock on pasture. There is still much to be learned about managed or rotational grazing, but it is the foundation of livestock management on many sustainable farms.
Activity 2. Ecological Pawprint Analysis
Career Pathway content standards
Projected Outcome | National Agricultural Education Standards Performance Element or Performance Indicators |
Activity Number(s) (in this section) |
---|---|---|
1. Identify sources and sinks for pollutants in livestock production systems and practices to minimize this pollution. | AS.08 Analyze environmental factors associated with animal production. ESS.03.03 Apply hydrology principles to environmental service systems. AS.07.02 Comply with government regulations and safety standards for facilities used in animal production. |
C-1, C-2 |
2. Describe how livestock production interacts with the surrounding environmental and genetic diversity. | ESS.03.02 Apply soil science principles to environmental service systems. | C-1 |
3. List ways in which sustainable livestock production minimizes energy waste. | NRS.02.04 Demonstrate natural resource enhancement techniques. ESS.04.02 Manage safe disposal of all categories of solid waste. ESS.05.01 Compare and contrast the impact of conventional and alternative energy sources on the environment. |
C |
4. Describe how sustainable practices can affect farm profitablity. | CS.03.03 Flexibility/Adaptability: describe traits that enable one to be capable and willing to accept change. AS.08 Analyze environmental factors associated with animal production. |
C |