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Changes in Manure Management in the Hog Sector: 1998-2004
Nigel Key, William D. McBride, and Marc Ribaudo
Economic Information Bulletin No. (EIB-50) 29 pp, March 2009
Economic competition has driven rapid changes in the U.S. hog industry over the last 10 years.
Production has shifted to larger operations that increasingly specialize in a single phase of hog
production and are organized under production contracts. This expansion and consolidation
means that fewer operations now manage an increasing volume of hog manure, magnifying environmental
risks if it is mismanaged. Pollutants such as nutrients (nitrogen and phosphorus),
ammonia, methane, and odor can originate from production houses where animals are kept,
from manure storage structures such as tanks and lagoons, or from fields where manure is
applied.
What Is the Issue?
The changing structure of hog farms is altering manure management practices, as larger operations
seek to manage nutrients on a limited cropland base. At the same time, strengthening of the
Clean Water Act with regard to runoff from manure nutrients, State regulations like the 1997
moratorium on hog farm expansion enacted by North Carolina, and local conflicts over odor are
requiring producers to alter their manure management practices. Information about the effects of
recent policies and structural changes on manure management technologies and practices, the
use of nutrient management plans, and manure application rates is useful for evaluating the
effectiveness of environmental policies and determining future policy needs.
What Are the Major Findings?
Over 1998-2004, the total number of U.S. hog operations fell by about 40 percent, and the average
inventory grew from 2,589 to 4,646 head per farm. Data from hog producer surveys administered
in 1998 and 2004 indicate that large hog producers (1,000 animal units or more) are altering
their manure management practices to mitigate the environmental effects of increased concentration.
In particular, the largest farms removed more manure from their operations (especially
by giving it away for free) and applied less commercial fertilizer to crops receiving manure in
2004 than in 1998. Also, in accordance with EPA regulations, large hog operations conducted
more nutrient testing of manure, increased the use of microbial phytase in feed (which reduces
nutrients in manure), and increasingly followed comprehensive nutrient management plans.
Additional trends that suggest greater adherence to environmental regulations by the largest hog
farms include: (1) a decline in the spreading of solid manure and liquid manure without physically
injecting it into the soil (these two practices increase the risk of nutrient loss to the atmosphere
and runoff); (2) a decline in the quantity of manure applied per acre; (3) a decline in the nutrients
excreted per animal due to an increase in feed efficiency; and (4) an increase in the share of farms
removing manure from their operation.
The increasing concentration of hog production on large operations is expected to continue, meaning that manure
management will continue to be an important issue to the hog industry and to others concerned with its environmental
impact. Results of this research suggest that there still is significant room for reducing the environmental
impact of manure through improved management. For example, hog operations, on average, apply manure to less
than 30 percent of available crop acreage. Policy incentives, along with technological innovation, are likely to play an
important role in the future of hog manure management and its environmental impact.
How Was the Study Conducted?
This study uses information from surveys of U.S. hog producers conducted in 1998 and 2004 as part of USDA’s annual
Agricultural Resource Management Survey (ARMS). The detailed surveys cover a cross-section of U.S. hog operations
and collect information on production costs, business arrangements, production facilities and practices, and
farm operator and financial characteristics. The surveys also provide information about manure storage and handling,
fertilizer use, manure application techniques, Environmental Quality Incentives Program (EQIP) payments, the
use of comprehensive nutrient management plans, and manure application rates. The data allow us to document the
current state of manure management and track producers’ responses to existing and anticipated manure-related regulations.
Data from the surveys are analyzed by farm size according to the number of animal units (1,000 pounds of
live animal weight) produced. Because larger hogs produce more manure, animal units provide a consistent measure
for comparing farms that produce hogs at different stages of the production cycle.
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