Alabama Certified Animal Waste Vendor Training
Module 2. Science behind the Rules and NRCS's Code 590
The "rules" that we are focusing on are Alabama's 2000 CAFO/AFO Rules which set up the CAWV program by stating that a CAWV must " . . . effectively manage, handle, transport, store, and properly land apply AFO waste in a manner that meets or exceeds NRCS technical standards and guidelines . . . ".
However, this one statement in ADEM's CAFO/AFO Rules " effectively make NRCS's technical standards and guidelines "THE LAW". These "technical standards and guidelines" are numerous and complicated. The local Soil and Water Conservation District office in your home county or your local county Cooperative Extension office may have them. The best source of this information is the Extension animal waste management web site: http://www . aces.edu/dept/aawm
Most of the best management practices that you'll need to know are in the NRCS technical standard known as "NRCS Nutrient Management Code 590." Each state has adopted its own 590 Code that meets or exceeds NRCS's federal Code 590. In Alabama this code established BEST MANAGEMENT PRACTICES or BMPs for " . . . managing the amount, source, placement, form and timing of application of nutrients and soil amendments".
You can review the entire code or only part of it at this web site: http://www.aces.edu/department/aawm/al590.pdf
Code 590 requires that each field, site, or farm be evaluated for risk of vulnerability of nitrogen and phosphorus to impact water resources. This evaluation uses all available information, such as soil ratings for leaching of soluble nutrients, soil infiltration rates, geology reports, sinkhole maps, stream classification, proximity of site to wells and streams, etc. The Phosphorus Index for Alabama is used to assess the potential risk of phosphorus movement into water on all fields or portions of fields that will have animal manure, poultry litter, compost or other organic by-products applied on them.
NRCS Agronomy Tech Note AL-72, Jan2001, which describes the Phosphorus Index (PI), can be reviewed at
http://www.aces.edu/department/aawm/PINDEXFinal2001.pdf
A Phosphorus Index Worksheet is used for this phosphorus risk assessment
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The following BMPs were taken from the Code 590
BMP: Consider Other Sources of Nutrients
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| Some of these BMPs are very practical and are just common sense practices such as the one for managing available nitrogen from legume cover crops. |
BMP: Apply Nutrients Based on Soil Test
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| Another BMP recommends doing what we have always done, apply nutrients based on a soil test report for the intended land use. This also assures that the crop needs are considered |
Nutrient planning and application should be based on current soil test results and recommendations developed in accordance with Auburn University Soil Testing Laboratory guidance or industry practice if recognized by the Auburn University Soil Testing Laboratory. Current soil tests are those that are no older than three years.
BMP: Apply Nutrients Within 30 Days Of Planting
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| The presidedress soil nitrate test has been used to determine if there is enough soil nitrogen present at sidedressing time to make a corn crop without additional fertilizer nitrogen. What was found in North Alabama is that you needed around 28 parts per million nitrate-nitrogen in the soil at sidedressing time in order to make 100% of the potential for corn grain yield. All of these sites in the above figure had been fertilized with poultry litter. If the litter was applied more than 30 days prior to planting, we were always below the 28 ppm level and still had to sidedress the crop with additional fertilizer N. If we applied it within 30 days of planting, there was adequate presidedress soil nitrate in the soil and no more had to be added. |
It makes economical sense to apply the nitrogen (e.g., animal manures) within 30 days of planting. So, what happened to all that nitrogen if it is applied at the wrong time? It ends up as nitrate in our groundwater or runs off into our streams, lakes, rivers, and ultimately, the Gulf of Mexico where it is considered a serious pollutant.
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| This study at the Prattville Experiment Field shows how quickly nitrogen in the upper 2 feet of soil can be lost during two growing seasons. |
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| One of the main reasons for this rapid loss of nitrate is our rainfall pattern. The figure above for the Birmingham , Alabama , area indicates a lot more rainfall (precipitation) from October through April than evaporation and plant uptake ( evapotranspiration ). This means a much higher risk for runoff and leaching during the cool months of the year. |
BMP: Apply No More than 30#/Acre In N.A.L. Winter
| One of the most controversial aspects of the Code 590 is the line above which no animal manures should be applied between November 15 and February 15. This is really no change in previous policy and recommendations in that animal manures must be applied only to actively growing crops. |  |
In 2002, the NRCS Code 590 for Alabama was changed such that winter application of manure in North Alabama is now a "consideration" rather than a hard and fast rule. Where plants are actively growing and are expected to be able to take up the nutrients applied, winter application may be permitted. However, this must be justified in a nutrient management plan.
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| As an example, note that fescue in North Alabama produced no harvestable dry matter yield in November through February in this study. There was a little growth in Central Alabama |
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This chart from the book, Southern Forages, indicate very little forage availability in December through February for most cool-season forages |
When you consider that the winter months produce the highest average rainfall (precipitation) and the lowest average evapotranspiration or plant use plus evaporation, then there is a tremendous risk for nutrient loss during the winter months throughout Alabama . Nitrate leaching to groundwater and phosphorus runoff in surface water are the major reasons we are concerned about water quality in Alabama .
WHAT SHOULD I DO?
Okay, so the research indicates that we should not, as a general rule, be spreading animal waste in the winter when not much is growing. What should a CAWV do when asked to spread for a customer in the winter?
Ask the following questions:
- "Do you have a nutrient management or conservation plan which specifies winter application?" If so, follow that plan.
- "Do you have an actively growing crop that can use the nutrients applied?" About the only cool season crop that makes adequate growth during the fall and winter is cereal rye. On the average, it can use about 30 pounds of N per acre or about 1/2 ton of broiler litter or 1 ton of wet breeder litter per acre. This isn't much!
- "Were any nutrients fall applied?" If so, chances are that more should not be added.
Check out the link to the NRCS Code 590 in order to answer the questions for this module about best management practices http://www.aces.edu/department/aawm/al590.pdf
Please return to the Course Content page (click >Course Content...> on the WebCT navigation bar at the top of this window) to take the Self-Help Test for this Module.