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In this issue
The Science of Smell
Beef News
Soybean Cyst – Time to Scout
Dairy Producers Learn About the Phosphorus Index
The Science of Smell
By Dave Stender, ISUE Swine Field Specialist
Several new publications
from Iowa State University Extension discuss the science of odor
perception. Odors are important to daily living. Odors stimulate
appetites and sometimes can alert to the presence of disease. A number of
diseases have characteristic odors, gangrene for example. Detectable odors
can have a significant impact on people. Many associate odors with past
experiences which can affect a person’s mood. Infants appear to like all
classes of odorous materials, perhaps because of lack of previous experience
and their curiosity.
There are wide
differences in people’s ability to smell odors. More than a thousand-fold
difference can exist between the least and most sensitive individuals.
Differences can be because of age, smoking habits, gender, nasal allergies
or head colds. Generally people can distinguish between more than 5,000
odors, some more than others.
The sense of smell is
the least understood of the senses, many theories have been proposed to
describe the mechanism of smelling odors, and most are either a physical
theory or a chemical theory. The most popular chemical theory says odor
molecules bind to receptors that stimulate olfactory nerve fibers. Receptor
sensitivity would explain the difference in odor detection for different
chemicals. Odor adaptation is when people get accustomed to an odor. This
situation applies to swine producers working in facilities as they become
unaware of the odor. On average, olfactory receptors can renew themselves
every thirty days.
Odor chemistry is
complex and poorly understood. More than 75 odorous compounds have been
identified in swine manure so far. Partial decomposition of manure gives
off a variety of odor compounds such as volatile organic acids, aldehydes,
ketones, amines, sulfides, thiols, indoles, and phenols. These intermediate
metabolites produce an offensive smelling product. Given enough time these
intermediates metabolize mostly into non-odorous methane. Background levels
of sulfur in water may also be a source of odor in swine manure.
There are 7 primary odor
classes of smells. However, more than 50 single substances have been
identified in odor studies, suggesting that there may be 50 or more types of
smells such as burnt, musky, floral, pungent, putrid, minty, etc. Usually,
an odor is a combination of many scents. That is true especially in animal
production facilities where one odor may be dominant to another or the two
odors may be smelled at the same time as individual odors. Odor has a
complex nature because odors can interact with each other. That is the
primary challenge in determining how best to prevent odor formation.
A basic understanding
that manure odors come from the incomplete breakdown of manure may be
helpful. Recent research shows that at least some of these odors could be
the result of excess protein in the diet. Management technologies used to
increase the accuracy of predicting feeding requirements may become more
important in the future. Using synthetic amino acids and calculating the
lean growth curve for a swine operation could become more important, not
only to maximize profit, but also to reduce the potential amount of volatile
odors from swine manure.
Information contained in
this article was extracted from PM-1963a & b. These ISU publications were
released in May, 2004. Check with your local Extension office for more
information. The next two publications in this series: Odor Detection and
Measurement (PM-1963c) and Principles of Odor Control (PM-1963d) are
scheduled for release later this fall.
Beef News
by Beth Ellen Doran, ISUE Beef Field Specialist
Solids Settling at Field Day - The
Iowa Department of Natural Resources (IDNR) has been checking open beef
feedlots as part of their follow-up to the Iowa Feedlot Plan. What is the
minimum required of a feed yard producer? Current IDNR rules require all
open feedlots (regardless of size) to remove settleable solids before any
liquid is allowed to leave the feedlot.
If you would like to see how solids settling works, Iowa State University
Extension is featuring solids settling as a part of the ISU Experimental
Farm Field Day at Castana on August 24 from 1:00 to 3:30 p.m. The key topic
is controlling feedlot runoff.
The Experimental Farm has a 100-head open beef feedlot that features solids
settling, vegetative filter strips and spreaders. The vegetative filter
strip uses a grassed terrace to improve the quality of the feedlot runoff.
The spreaders are 2-in x 10-foot boards set on edge at spaced intervals in
the terrace. Spreaders are used to slow down the runoff and prevent
channeling and erosion in the filter strips.
Other topics for the field day will include the use of condensed distillers’
solubles in stocker and feedlot cattle rations, soybean rust, and producing
pigs for niche markets. Pre-registration is not necessary. For directions
to the Experimental Farm, call
712-885-2802.
Ag Census - Every five years, the USDA's National Agriculture
Statistics Service surveys America's farmers and ranchers to gather data
about agriculture, the nation's largest industry. The survey indicated that
nearly half of all farms have cattle. Over 1 million farms produce 95.5
million cattle, 4.5% fewer than five years ago. Nearly 800,000 operations
have beef cattle. There are approximately 33 million head of beef cows,
making the average herd size 42 cows. There were about 716,000 farms with
cropland used for pasture or grazing, accounting for 60 million acres or
about 85 acres per operation. However, there are also 396 million acres of
pasture or range (other than cropland) on 850,000 farms. This is an average
of 465 acres per operation.
The top five states in value of agricultural products sold are California
($25.7 billion), Texas ($14.1 billion), Iowa ($12.3 billion), Nebraska ($9.7
billion) and Kansas ($8.7 billion). Thousands of aggregated facts and
figures can be accessed online from the NASS website at
www.usda.gov/nass/ by clicking on "Census of Agriculture.
Iowa State Fair Celebrates 150 Years - If ever there was a year to
attend the Iowa State Fair, this is the year. From August 12-22, the
country's most famous state fair and Iowa's largest tourism event will
celebrate its sesquicentennial. According to USA Weekend, the Iowa State
Fair was named one of Amerca's top ten fun places! What's in store?
Everything from a 500-person, 50-wagon, 112 mile horse caravan form
Fairfield, IA (the Fair's first site) to a torch run from all four corners
of the state. Plus the famous Butter Cow, the Glenn Miller Orchestra and
spectacular fireworks choreographed to music. And don't forget the 17
different beef shows, cheeseburger fries and the Super Bull. For detailed
information about the Iowa State Fair, visit the website at
www.iowastatefair.com and remember that after 150 years, the Fair is
"Still the One!"
Soybean Cyst - Time
to Scout!
by Joel DeJong, ISUE Crops Specialist
Soybean cyst nematode (SCN)
is an important, widespread soybean pest in Iowa that often goes unnoticed.
The only consistent and reliable sign of an SCN infestation in the field is
the presence of adult SCN females and cysts (dead females) on the roots of
infected soybean plants. Adult SCN females and cysts are small, round, and
white to yellow, each approximately the size of a period at the end of a
sentence.
I have seen some cases in the NW
corner of Iowa this year where root systems with cysts can be found in
infected fields. Consequently, I believe now is still a good time to scout
fields for SCN by checking soybean roots for females and cysts. You will be
able to see females and cysts on roots of infected plants through much of
the growing season, until late summer or early fall when the plants begin to
mature. It is easier to observe the nematode on soybean roots early in the
season because the females and cysts occur on new roots that can be easily
dug from the soil surrounding the base of the stem of the plant. Later in
the season, adult SCN females and cysts appear on new roots that are located
deeper down in the soil as well as farther laterally from the stem.
To scout for SCN in fields where the nematode has not yet been found, you
may target fields in which soybeans has been grown frequently in the past
and fields where soybean yields have declined over time for no apparent
reason.
Because SCN is spread by the
movement of infested soil, checking roots of plants near the entrance of
fields where farm equipment enters and along fence lines where wind-blown
soil accumulates also may increase the likelihood of finding SCN-infected
plants.
Collection of soil samples from fields
suspected of being infested with SCN is an alternative to digging soybean
roots and looking for adult females and cysts. Soil sampling can be done at
any time during the growing season. Soil samples should be submitted to a
private soil testing laboratory that offers nematode testing or to the ISU
Plant Disease Clinic for extraction and counting of SCN eggs. Samples sent
to the ISU Plant Disease Clinic should be accompanied by a completed Plant
Nematode Sample Submission Form (ISU Extension publication PD 32).
Currently there is a $15 charge for processing each sample. Detailed
instructions on how to collect a representative soil sample for detection of
SCN can be found on the back of PD 32.
Iowa State University Extension
publication IPM 47s,
Scouting for Soybean Cyst Nematode, illustrates the recommended
procedures for scouting for SCN. Single copies of this publication are
available free of charge from your local county extension office.
Dairy Producers Learn
about the Phosphorus Index
By Chris Mondak, ISUE Dairy Specialist
On June 30 IMMAG members
visited NW Iowa dairy farms to talk with dairy producers and see the various
methods of manure management practices so they could better understand the
manure management and environmental challenges faced by the dairy producers.
IMMAG is a state-wide
committee whose members represent organizations such as NRCS, DNR, Iowa Farm
Bureau, Agribusiness Association of Iowa, commodity groups, Conservation
Districts, and ISU Extension. The mission of IMMAG is to provide a vehicle
for a coordinated, comprehensive approach to improve manure management in
Iowa by providing accurate information and educational programs.
At each farm visited
questions came up about the Phosphorus Index. Key points producers learned:
-
Phosphorus, an essential nutrient for
plants, becomes an environmental problem when soil erosion and run-off
carries phosphorus to surface waters where it can cause excessive algae
growth.
-
The Phosphorus Index is a method to
calculate the potential risk for phosphorus to move from a field to
surface waters. The calculation for each field takes into account not
only the soil P level, but also several other factors including presence
of conservation practices, slope, degree of soil erosion, distance to
streams, fertilizer and manure application practices.
-
The Phosphorus Index was developed by
NRCS, the National Tilth Lab, and ISU. The intention is that the Index
will help producers make decisions, prevent P run-off to surface water,
and increase nutrient application efficiency while preventing phosphorus
overfertilization.
-
A very important point: A field’s soil
phosphorus level is not that field’s P-Index! A field could
possibly have a high phosphorus soil test level, but due to factors such
as conservation practices utilized, have a low Phosphorus Index.
Similarly, a field with a low phosphorus soil test could have a high
Phosphorus Index due to field shape, location, or lack of conservation
practices.
-
Starting October 2004, Manure Management
Plans will involve use of the Phosphorus Index information. A Manure
Management Plan is required for confinement dairies that have more than
500 animal units, which means 357 actual cows after dividing 500 by
1.4(adult dairy cow factor) = 357.
-
Confinement dairies, equal or less than
500 animal units, must still apply manure in a manner that does not
cause a water quality violation, including meeting separation distances
for land application of manure.
To learn more about
IMMAG, see the website at www.extension.agron.iastate.edu/immag. To contact
the coordinator, Angie Rieck-Hinz, or to get on the mailing list for the
monthly newsletter update, call 515-294-9590 or send message to
amrieck@iastate.edu.
To get Phosphorus-Index
information about your fields, contact your local NRCS office, or call Chris
Murray at 515-284-4370. Access the NRCS website at
www.ia.nrcs.usda.gov. To be thorough, contact Iowa DNR, Spencer office,
to understand how the Phosphorus Index will affect your manure management
plan.
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