Why Be Concerned?
Managing the land application of animal waste to protect water quality depends on applying rates based on crop requirements and soil conditions, knowing the composition of the animal waste, avoiding runoff from recent applications, and protecting the application areas from runoff and soil erosion. Runoff from fields and water leaching through soil can carry plant nutrients, soil, microorganisms, and other potential pollutants from the fields to surface water or groundwater.
Animal wastes, if not managed properly, can become a source of nitrate and disease-causing organisms to both surface water and groundwater. Nitrogen from animal waste can also be a source of nitrates in groundwater. Nitrate levels above the federal and state drinking water standard of 10 milligrams per liter (mg/L; equivalent to parts per million for water measure) nitrate-nitrogen can pose health problems for infants under 6 months of age. This condition in infants is often described as methemoglobinemia (blue baby syndrome). Nitrates can also affect adults, but evidence of the consequences is much less certain. In addition, young livestock are susceptible to health problems from high nitrate-nitrogen levels, especially in combination with high levels of nitrate-nitrogen from feed sources.
Phosphorus from animal waste that enters surface water and nitrate-nitrogen from groundwater that flows into surface water can supply algae and aquatic plants with essential nutrients that stimulate their growth. When this excessive growth dies and begins to decay, the dissolved oxygen level in the water will go down, and if it gets too low, fish and other water dwelling organisms will die. In addition, other species of algae that are stimulated by plant nutrients reproduce quickly, creating toxic algal blooms. Algae can also compete for resources with other aquatic species and contribute to reduced habitat quality.
Fecal bacteria in animal waste can contaminate surface and groundwater, causing such infectious diseases as dysentery, typhoid, and hepatitis. Typical water purification practices such as chlorination are not effective in controlling some of the pathogens found in animal waste. The best protection is to limit the possibility of them reaching the water resources.
Sometimes management practices to protect groundwater can conflict with practices to protect surface water because the transfer of nitrate-nitrogen and phosphorus are so different in most Pennsylvania soils. Specific site knowledge and evaluation may be necessary to determine which practices should have the highest priority in a management program.
Not only the possible water quality impacts of land applying animal waste, but considering other consequences or perceptions of the practices by neighbors can be part of a successful land application program. Being aware of holidays, weekends, or other special occasions in the neighborhood and not scheduling applications during those times can promote good community relations. Special care to not apply animal waste too close to property lines or to incorporate applications to reduce odors and pests can also be part of comprehensive land application management. Losses of nitrogen to the atmosphere from surface applied animal waste will probably be a management consideration in the future.
The goal of Pennsylvania Farm-A-Syst is to help you protect groundwater and surface water, shared resources which are important to everyone.
How to Rank Groundwater and Surface Water Protection Using This Worksheet
- You can select from a wide range of conditions and management practices that are related to potential groundwater and surface water contamination.
- You can rank your operation conditions and management practices according to how they might affect groundwater and surface water.
- Based on your overall ratings, you can determine which of your conditions or practices are reasonably safe and effective, and which might require modification to better protect groundwater and surface water.
How to Complete the Worksheet
Download the Animal Waste Land Application Management Worksheet . Follow the directions as listed on page 1 of the worksheet. The evaluation should take 15–30 minutes to complete and determine your ranking. Evaluate each land application site on your farm. There are spaces provided to rank up to three sites. A site will usually be a group of fields that are on the same farm and generally are managed the same. Different sites might be farms other than where the animals generating the waste are located or rented farms. If you have more than three sites, please use another worksheet. If you are unfamiliar with any of the terms used, refer to the glossary provided with this worksheet.
Information derived from Farm-A-Syst worksheets is intended only to provide general information and recommendations to farmers regarding their own farm and farmstead practices or conditions. It is not the intent of this educational program to keep records of individual results. However, the results may be shared with others who will help you develop a resource management plan.
How to Use These Rankings
Step 1: Now that each feature has been ranked, add all these rankings together and put that value in the “Total” box at the end of the worksheet. Transfer that number to the box below.
Step 2: Divide the value in the “Total” box by the number of features ranked.
Step 3: Repeat for the remaining sites. Calculate the average ranking for all sites combined.
Step 4: Evaluate the overall management practices and site conditions.
- 3.6–4.0 = best management
- 2.6–3.5 = good management
- 1.6–2.5 = fair management
- 1.0–1.5 = poor management
This ranking gives an idea of how animal waste land application management as a whole might affect water quality. This ranking should serve only as a very general guide, not a precise diagnosis. Since it represents an averaging of many individual rankings, it can mask any individual rankings (such as 1s and 2s) that should be of concern.
Step 5. Look over the rankings for individual features of each site:
- Best (4s): the current ideal; should be the goal despite cost and effort
- Good (3s): provides reasonable surface and ground-water protection
- Fair (2s): inadequate protection in many circumstances
- Poor (1s): poses a high risk of polluting surface water or groundwater
Regardless of the overall ranking, any individual rankings of “1” should receive immediate attention. Some concerns can be taken care of right away; others could be major or costly projects, requiring planning and prioritizing before taking action.
Step 6. Consider how to modify farm management practices or site conditions to better protect water quality. Contact the local conservation district, Extension office, or the USDA Natural Resources Conservation Service for ideas, suggestions, or guidance. Guidelines that comply with Department of Environmental Protection regulations concerning field application of manure are available in the Pennsylvania Manure Management Manual for Environmental Protection and its supplements. Land application of animal waste on the most intensive animal operations is regulated in Pennsylvania under Act 6, Pennsylvania’s Nutrient Management Law. For more details or to determine if you qualify, contact any of the agencies listed above.
Pennsylvania Farm-A-Syst is a cooperative effort among Penn State Extension, Pennsylvania Association of Conservation Districts, Pennsylvania Department of Agriculture, Pennsylvania Department of Environmental Protection, and USDA Natural Resources Conservation Service.