4 pp., 4 photosSummer drought can make dust control in feedyards more challenging than usual. Supplemental water may not keep pace with daily evaporation. The key to dust control is managing the depth of dry manure in the pens by harvesting manure more frequently, and planning ahead when a drought is projected

Auvermann, Brent W.

Parker, David B.

Sweeten, John M.

Texas A&M University

Recent summer droughts in Texas have made dust
control in feedyards in the semi-arid High Plains far
more challenging than usual. High winds, high day-
time temperatures and low humidity accelerated the
drying rate of manure on the corral surface. Then,
light winds and temperature inversions in the late
evening occasionally created extreme dustiness at
ground level. Such concentrations of dust may be a
risk to the respiratory health of cattle and may be a
nuisance for neighbors. Frequent manure harvesting
can be part of a drought-management scheme to con-
serve water and control dust.
Background
“Scraping pens” is not a new concept to the feed-
yard manager, who knows that deep accumulations of
manure can nibble away at profit margins when
muddy bogs, rain, snow or cold weather combine to
increase an animal’s maintenance requirements.
However, many managers are concerned only with
removing manure before winter or before the rainy
season.
Industry representatives and Extension agricultural
engineers in Texas have advocated “harvesting
manure” instead of “scraping pens.” The difference
between the two is subtle and relates more to objec-
tives and attitude than simply to the act of removing
manure from the corral surface. However, the impli-
cations are profound. Harvesting manure means
scraping the corrals with a pre-planned, holistic man-
agement purpose to yield better quality manure;
reduce mud, dust and odor; and improve corral
drainage and appearance. The Total Quality Manure
Management Manual published by the Texas Cattle
Feeders Association in June 1995 presented these
holistic management principles in a compelling way.
Summer 2000
Applying water to the feedlot surface with a sprin-
kler system, mobile tanker or reel-mounted “big gun”
is the dust control method many feedyard managers
use. Under normal conditions, water application that
keeps the moisture content of manure between 25
and 40 percent (wet basis) reduces dust significantly
without creating severe odor problems.
The summer of 2000, unfortunately, was anything
but normal in Texas’ cattle-feeding country. In the
Amarillo area, where nearly two-thirds of the 19-inch
average annual rainfall normally occurs between May
and September, almost no rain fell from July to
September. The annual rainfall total was 6 inches (or
35 percent) below normal by October 1, when feed-
yards with solid-set sprinkler systems would ordinari-
ly be draining the systems in preparation for winter.
Daytime highs in the upper 90s and low 100s were
common into the first week of October. Some feed-
yard managers speculated that heat stress in the late
afternoon increased the aggressiveness of cattle, and
therefore the hoof action that generates feedyard dust.
Hot autumn afternoons frequently gave way to cool,
stable, calm evenings that capped the dust plumes
near the ground surface and allowed them to persist
for miles downwind, clearly observable to motorists
and residents. In such an extreme drought, attempting
to control the dust by trying to keep pace with daily
evaporation (i. e., by applying supplemental water or
by increasing the stocking density) was a losing
proposition.
Managing Dry Manure Depth
The mechanics of feedyard dust emission are rela-
tively simple. Although some dust results from wind
scouring (similar to wind erosion from cropland, for
E-52
11-00
Manure Harvesting Frequency—
The Key to Feedyard Dust Control in a
Summer Drought
Brent W.Auvermann, David B. Parker and John M. Sweeten*
*Assistant Professor and Extension Agricultural Engineer, The
Texas A&M University System; Assistant Professor of
Environmental Science and Engineering, West Texas A&M
University; and Professor and Extension Agricultural Engineer,
The Texas A&M University System.
example) and from truck traffic on unpaved roads,
most of the dust generated in a feedyard is caused by
cattle hooves trampling the dry, loose manure layer
on the corral surface. 
The deeper the layer of loose, dry manure, the
more dust will be generated (Figs 1 and 2). Most of
the dust is generated in the late afternoon and
evening when cattle are most active. Lower tempera-
tures and wind speeds at this time of day tend to keep
the dust confined to a shallow layer (less than 50 feet
in some cases) of air immediately above the ground
(Fig. 3).
Making Supplemental Water
Go Further
The benefit of frequent manure harvesting goes
beyond direct dust control. Feedyards whose primary
dust control measure is applying supplemental water
can make their precious water go further by reducing
the depth of manure to which the water is applied.
That is especially true during a severe drought.
The manure layers in Figures 1 and 4 had a mois-
ture content of 10 to 15 percent (wet basis), far below
the 25 to 40 percent required for dust control. To con-
trol dust with water alone, then, the feedyard manag-
er would have to apply enough water to increase the
moisture content of the entire loose manure layer by
15 to 20 percent.  As a rule, raising the moisture con-
tent of a loose manure layer by 10 percent requires
5.6 gallons per head per 1 inch of loose manure depth
(based on a cattle spacing of 150 square feet per
head). For example, a 2-inch layer of loose manure
would require 28 gallons per head just to raise the
moisture content from 10 percent to 35 percent.
Simply wetting the surface of a deep manure layer
may eliminate dust from wind scour, but a bovine
hoof will easily penetrate the wetted surface and stir
up the dry material below. Where water is already in
short supply, manure harvesting reduces the amount
of water needed to achieve dust control and increases
the effectiveness of any water that is applied.
Manure can be harvested with tractor-drawn box
scrapers or elevating paddle scrapers. The collected
dry manure should be removed immediately from
pens, when practical, so that cattle do not disturb or
redistribute the loose material that has been collected.
If the loose material must be stored in the corral for a
short time, apply water, or perhaps effluent from a
runoff holding pond.
Figure 1.The layer of loose manure on this corral surface is 2 to 4 inches deep.
Figure 3. Increased cattle activity in the late afternoon and early evening often coincides with lower wind speeds at the
earth’s surface, cooler temperatures, and reduced turbulence. This confines feedyard dust to a shallow layer of air near
the ground.
Figure 2.The surface layer of loose manure on this recently scraped corral is less than an inch deep.
Timing Manure Removal
If a feedyard routinely has dust problems, the man-
ager should harvest manure more frequently. Most
feedyards scrape their corrals once every turn of cat-
tle (120 to 150 days), immediately after the cattle are
sold to the packing plant. Some remove manure less
frequently than that. If the machinery allows, manure
should also be harvested at the midpoint of the feed-
ing cycle, while the cattle are still in the corral. This
will not only improve dust conditions significantly,
but also will increase the dust-control value of any
supplemental water applied. If long-term weather
forecasts indicate there will be a drought the next
summer, beginning the manure-harvesting operations
in May or June is too late. Procrastination will force
the feedyard manager to play “catch-up” all summer
long. Feedyard managers should prepare for dust
problems early in the spring so that the average
manure depth across the feedyard is at its practical
minimum when summer arrives.
Figure 4. The two rows of corrals in the foreground were scraped several days before the photo was taken on a hot
September evening in 2000. Corrals in the background had not been scraped in several months.The difference in dust
emissions is visible and dramatic. Notice the occlusion of the lamps in the left of the photograph as a result of dust emis-
sions in the background. (A light breeze was blowing from right to left when the photo was taken.)
Produced by AgriLife Communications and Marketing,The Texas A&M University System
Extension publications can be found on the Web at: http://AgriLifebookstore.org
Educational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age or national origin.
Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amended, and June 30, 1914, in cooperation with the
United States Department of Agriculture. Chester P. Fehlis, Deputy Director,Texas Agricultural Extension Service,The Texas A&M University System.


English

Manure Harvesting Frequency: The Key to Feedyard Dust Control in a Summer Drought

Texas A&amp;M Repository

Recent summer droughts in Texas have made dustcontrol in feedyards in the semi-arid High Plains farmore challenging than usual. High winds, high day-time temperatures and low humidity accelerated thedrying rate of manure on the corral surface. Then,light winds and temperature inversions in the lateevening occasionally created extreme dustiness atground level. Such concentrations of dust may be arisk to the respiratory health of cattle and may be anuisance for neighbors. Frequent manure harvestingcan be part of a drought-management scheme to con-serve water and control dust.Background“Scraping pens” is not a new concept to the feed-yard manager, who knows that deep accumulations ofmanure can nibble away at profit margins whenmuddy bogs, rain, snow or cold weather combine toincrease an animal’s maintenance requirements.However, many managers are concerned only withremoving manure before winter or before the rainyseason.Industry representatives and Extension agriculturalengineers in Texas have advocated “harvestingmanure” instead of “scraping pens.” The differencebetween the two is subtle and relates more to objec-tives and attitude than simply to the act of removingmanure from the corral surface. However, the impli-cations are profound. Harvesting manure meansscraping the corrals with a pre-planned, holistic man-agement purpose to yield better quality manure;reduce mud, dust and odor; and improve corraldrainage and appearance. The Total Quality ManureManagement Manual published by the Texas CattleFeeders Association in June 1995 presented theseholistic management principles in a compelling way.Summer 2000Applying water to the feedlot surface with a sprin-kler system, mobile tanker or reel-mounted “big gun”is the dust control method many feedyard managersuse. Under normal conditions, water application thatkeeps the moisture content of manure between 25and 40 percent (wet basis) reduces dust significantlywithout creating severe odor problems.The summer of 2000, unfortunately, was anythingbut normal in Texas’ cattle-feeding country. In theAmarillo area, where nearly two-thirds of the 19-inchaverage annual rainfall normally occurs between Mayand September, almost no rain fell from July toSeptember. The annual rainfall total was 6 inches (or35 percent) below normal by October 1, when feed-yards with solid-set sprinkler systems would ordinari-ly be draining the systems in preparation for winter.Daytime highs in the upper 90s and low 100s werecommon into the first week of October. Some feed-yard managers speculated that heat stress in the lateafternoon increased the aggressiveness of cattle, andtherefore the hoof action that generates feedyard dust.Hot autumn afternoons frequently gave way to cool,stable, calm evenings that capped the dust plumesnear the ground surface and allowed them to persistfor miles downwind, clearly observable to motoristsand residents. In such an extreme drought, attemptingto control the dust by trying to keep pace with dailyevaporation (i. e., by applying supplemental water orby increasing the stocking density) was a losingproposition.Managing Dry Manure DepthThe mechanics of feedyard dust emission are rela-tively simple. Although some dust results from windscouring (similar to wind erosion from cropland, forE-5211-00Manure Harvesting Frequency—The Key to Feedyard Dust Control in aSummer DroughtBrent W.Auvermann, David B. Parker and John M. Sweeten**Assistant Professor and Extension Agricultural Engineer, TheTexas A&M University System; Assistant Professor ofEnvironmental Science and Engineering, West Texas A&MUniversity; and Professor and Extension Agricultural Engineer,The Texas A&M University System.example) and from truck traffic on unpaved roads,most of the dust generated in a feedyard is caused bycattle hooves trampling the dry, loose manure layeron the corral surface. The deeper the layer of loose, dry manure, themore dust will be generated (Figs 1 and 2). Most ofthe dust is generated in the late afternoon andevening when cattle are most active. Lower tempera-tures and wind speeds at this time of day tend to keepthe dust confined to a shallow layer (less than 50 feetin some cases) of air immediately above the ground(Fig. 3).Making Supplemental WaterGo FurtherThe benefit of frequent manure harvesting goesbeyond direct dust control. Feedyards whose primarydust control measure is applying supplemental watercan make their precious water go further by reducingthe depth of manure to which the water is applied.That is especially true during a severe drought.The manure layers in Figures 1 and 4 had a mois-ture content of 10 to 15 percent (wet basis), far belowthe 25 to 40 percent required for dust control. To con-trol dust with water alone, then, the feedyard manag-er would have to apply enough water to increase themoisture content of the entire loose manure layer by15 to 20 percent.  As a rule, raising the moisture con-tent of a loose manure layer by 10 percent requires5.6 gallons per head per 1 inch of loose manure depth(based on a cattle spacing of 150 square feet perhead). For example, a 2-inch layer of loose manurewould require 28 gallons per head just to raise themoisture content from 10 percent to 35 percent.Simply wetting the surface of a deep manure layermay eliminate dust from wind scour, but a bovinehoof will easily penetrate the wetted surface and stirup the dry material below. Where water is already inshort supply, manure harvesting reduces the amountof water needed to achieve dust control and increasesthe effectiveness of any water that is applied.Manure can be harvested with tractor-drawn boxscrapers or elevating paddle scrapers. The collecteddry manure should be removed immediately frompens, when practical, so that cattle do not disturb orredistribute the loose material that has been collected.If the loose material must be stored in the corral for ashort time, apply water, or perhaps effluent from arunoff holding pond.Figure 1.The layer of loose manure on this corral surface is 2 to 4 inches deep.Figure 3. Increased cattle activity in the late afternoon and early evening often coincides with lower wind speeds at theearth’s surface, cooler temperatures, and reduced turbulence. This confines feedyard dust to a shallow layer of air nearthe ground.Figure 2.The surface layer of loose manure on this recently scraped corral is less than an inch deep.Timing Manure RemovalIf a feedyard routinely has dust problems, the man-ager should harvest manure more frequently. Mostfeedyards scrape their corrals once every turn of cat-tle (120 to 150 days), immediately after the cattle aresold to the packing plant. Some remove manure lessfrequently than that. If the machinery allows, manureshould also be harvested at the midpoint of the feed-ing cycle, while the cattle are still in the corral. Thiswill not only improve dust conditions significantly,but also will increase the dust-control value of anysupplemental water applied. If long-term weatherforecasts indicate there will be a drought the nextsummer, beginning the manure-harvesting operationsin May or June is too late. Procrastination will forcethe feedyard manager to play “catch-up” all summerlong. Feedyard managers should prepare for dustproblems early in the spring so that the averagemanure depth across the feedyard is at its practicalminimum when summer arrives.Figure 4. The two rows of corrals in the foreground were scraped several days before the photo was taken on a hotSeptember evening in 2000. Corrals in the background had not been scraped in several months.The difference in dustemissions is visible and dramatic. Notice the occlusion of the lamps in the left of the photograph as a result of dust emis-sions in the background. (A light breeze was blowing from right to left when the photo was taken.)Produced by AgriLife Communications and Marketing,The Texas A&M University SystemExtension publications can be found on the Web at: http://AgriLifebookstore.orgEducational programs of the Texas AgriLife Extension Service are open to all people without regard to race, color, sex, disability, religion, age or national origin.Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amended, and June 30, 1914, in cooperation with theUnited States Department of Agriculture. Chester P. Fehlis, Deputy Director,Texas Agricultural Extension Service,The Texas A&M University System.

https://oaktrust.library.tamu.edu/bitstream/1969.1/86972/1/pdf_1370.pdf

Manure Harvesting Frequency: The Key to Feedyard Dust Control in a Summer Drought

Abstract

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Texas A&M University

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Manure Harvesting Frequency: The Key to Feedyard Dust Control in a Summer Drought

Abstract

Similar works

Full text

Available Versions

Texas A&M University

Texas A&amp;M Repository

Texas A&M Repository