1Richard Coffey (Co-Chairman), Department of Animal Sciences; Ron Bowman (Co-Chairman), Nelson County Extension Agent for Agriculture and Natural Resources; Les Anderson, Department of Animal Sciences; Jenny Cocanougher, Agricultural Programs; Bill Crist, Department of Animal Sciences; Ron Fleming, Department of Agricultural Economics; Kim Henken, Agricultural Programs; Janet Johnson, Allen County Extension Agent for Family and Consumer Sciences; Reva Mitchell, Henderson County Extension Agent for 4-H/Youth Development; Doug Overhults, Department of Biosystems and Agricultural Engineering; Tony Pescatore, Department of Animal Sciences; Monroe Rasnake, Department of Agronomy; Scott Samson, Department of Sociology; and Bill Thom, Department of Agronomy.
Farmers have routinely used animal manure to provide essential plant nutrients (namely nitrogen, phosphate, and potash) and to improve soil quality. Applying manure to the land remains today as a proven, environmentally sound method for recycling nutrients to the soil. However, evolving agricultural technology and new environmental concerns have added numerous constraints to this age-old practice.
Crop and animal production systems have become more specialized during the past few decades. Livestock and poultry operations are fewer in number but larger in size. Some animal operations are now concentrated in certain geographical regions. These changes in animal production have led many to question whether these larger animal operations will produce more manure than the current agricultural land base can use.
The amount of manure needed for a crop or pasture is best determined on a farm-by-farm basis. On a broad scale, however, available manure nutrients and typical nutrient removals by plants can be estimated. University of Kentucky Extension personnel recently completed this type of broad (county-by-county) assessment. This publication provides a summary of that work.
Results for each county are presented as color-coded maps (Figures 1, 2, and 3) in this publication. Following are a few summary points from those maps:
The assessment results are only a snapshot of potential manure nutrient use on a relatively large scale (a countywide basis) and do not provide for evaluations at the individual farm level. Due to the broad nature of the assessment, prudence must be used when drawing conclusions from the results.
The assessment may be most useful as a benchmark of the potential of current manure utilization for a county or region of the state. When used in this manner, the assessment results may help:
The assessment does not take into account the manure management practices currently being used on individual farms and should not be used to:
How the Study Was Done
The assessment was based on a procedure developed by the Natural Resources Conservation Service (NRCS). It involved comparing the amount of manure nutrients produced annually by livestock and poultry to the amount of these nutrients removed from the land by crop and forage production each year. From this comparison, the apparent nutrient balance within each Kentucky county was estimated.
Animal inventories and crop production estimates for each county were obtained from the 1997-1998 Kentucky Agricultural Statistics report, the 1997 U.S. Census of Agriculture, and industry surveys. Animal species included were beef cattle, dairy cattle, swine, and poultry. Crop and forage production estimates were included for corn, corn silage, soybean, winter wheat, sorghum, barley, alfalfa hay, all other types of hay, burley tobacco, dark fire-cured and air-cured tobacco, and forage from grazed pastureland.
Amounts of nitrogen, phosphate, and potash excreted annually by livestock and poultry were estimated using average manure production and manure nutrient content values published by the American Society of Agricultural Engineers and the NRCS. These estimates were adjusted to account for manure and manure nutrient losses that typically occur during collection and storage of manure.
Annual removal of nitrogen, phosphate, and potash by crops and forages was estimated from data developed at the University of Kentucky and data reported by the NRCS.
A detailed discussion of the methods and assumptions used in assessment can be found in the Cooperative Extension Service publication Assessment of the Potential for Livestock and Poultry Manure to Provide the Nutrients Removed by Crops and Forages in Kentucky ( IP-56).
The assessment does not account for all factors that influence a county’s true balance of nutrients. Therefore, although the assessment may indicate livestock and poultry currently in place in a county are producing all the manure nutrients its crops and forages can remove, the county’s farms may have the ability to use additional manure nutrients and should be examined more closely.
As an example of how other factors can be important, consider the estimates for Muhlenberg County, which indicate that manure from livestock and poultry could supply 134% (an excess of 443,282 pounds) of the phosphate removed annually by the county’s crops and forages. However, the following factors illustrate that there is substantial potential to effectively use the apparent surplus of manure phosphate:
Therefore, it cannot be unequivocally stated that the limits of animal production have been reached in Muhlenberg County.
A simple countywide calculation of nutrients produced and nutrients removed does not provide a complete manure management picture. Developing solutions that are technically sound, environmentally responsible, and economically viable will require a cooperative effort between the agricultural community, local and state officials, regulators, University personnel, and citizen groups. To effectively evaluate potential developments in animal production, the following questions should be addressed on a farm-by-farm basis:
These estimates provide, for each Kentucky county, a snapshot comparison of nutrients supplied by manure and nutrient removal by crops and forages. For a majority of counties, nutrients from animal manure are insufficient to meet the nutrient removal capacities of crops and forages. However, more information and data collection is needed to gain a better understanding of each county’s true nutrient balance.
Regulations are currently in place to ensure animal operations use manure in an environmentally sound manner. The following highlights major environmental regulations: