Introduction to animal agriculture: manure handling systems. Manure is an
inescapable byproduct of livestock production; how it’s handled is becoming more and
more important, impacting not only the environment, but
the producers bottom line. This presentation is a brief look at
manure management systems. Manure can mean different things to
different people; this presentation defines manure as the
excretion of urine and feces from the animal including any bedding or feed that comes
along with the animals biological waste. With liquid manure systems waste water
and wash water also enter into the manure storage unit.
Manure is generally a mixture of water, organic matter, inorganic matter, like sand and salt, and
nutrients, like nitrogen and phosphorous. There are
also microorganisms that feed off the organic matter called fecal bacteria that come from the gut to the animal. A
common way to measure manure production is with daily excretion, by weight
of manure, feces, and urine pounds of nutrients such as nitrogen
and phosphorous commonly quantified in the form of
phosphate and BOD, or biochemical oxygen demand, a common
measure of the organic content of the manure. The
primary goal of any manure handling system is to return nutrients produced by the animals back to the land. The
nutrient value of manure has been well recognized as long as livestock have
been raised. When Fritz Haber invented commercial
nitrogen fertilizer in 1908 and marketed it in 1910 manure
handling systems began to change; commercial fertilizer caught on because
it was cheap and easy to use. Meanwhile, manure was
seen as a waste to be simply disposed of. Unfortunately, some farmers still consider manure a waste, but more and more are taking advantage
of its value. There are many options for getting manure back to the land where
the nutrients can be put to work. We’ll look at different handling systems
in upcoming slides these include pastor systems, store in
place, and collection and storage. Animals haul
their own. Pasture animals eat grasses and other
plants from the ground and deposit manure in the same general area; this can be a very effective manure
management system, but depending on species pasture systems
are not always economically viable. Cattle and horses
are much more adaptable to pasture systems than pigs and poultry. Some dairy
operations use intensive rotational grazing systems where the animals are moved often
through small fenced pastures, or paddocks. Frequent and controlled movement of the
grazing animal is beneficial for the pasture grasses and distribution
of manure. Pasture is a cheap way of spreading manure with little need for
labor or equipment, but the distribution of manure is not
always uniform. Pasturing is limited in Minnesota
thanks to snow and cold weather. Store in place. Manure can also be
stored either temporarily, or long-term where animals are housed; swine, dairy, beef, and poultry farms can use this type
of direct deposit system. Bedding is added to keep the animals dry:
for swine, straw or corn stocks are used – depending
on temperature, humidity and animal size more bedding will be
added as needed. When the barns inhabitants are moved to
another building, or sent to market the barns are cleaned. Bedded pack barns are
used for heifers and for special care, or maternity areas. Packs are built primarily of straw with
daily additions of bedding to keep the pack dry. A relatively new system for housing
animals and storing manure are so-called compost dairy barns; these use sawdust for bedding mixed
with manure. A compost like material builds up in the
barn stirred twice a day while the animals are out for milking the compost gets deeper with time, as
much as three feet. Manure is removed from the barn once a year.
Most broilers and turkeys are raised on solid floors bedded with wood shavings; portions of the barn are clean between
flocks and more betting is added. The partial cleaning removes manure
build up around the animals food and water area. Manure can also be stored on open concrete or dirt lots with no
bedding. Cleaning frequency can vary from once a
day on concrete to a few times each year in open outside
lots. Store in place manure systems don’t
require a separate storage structure and in most cases the manure is only
handle once provided there’s crop land available at
the time when the manure must be hauled out. The expensive extra bedding and extra
labor to deal with it is one drawback. Good ventilation is also
needed to help remove moisture and gases that result from the manure and bedding as
they decompose. Collection systems. If manure is not
stored in place it must be collected and either hauled directly to the field, or to a storage
area. Manure collection and transport to storage typically requires both
additional labor and equipment. With deep pit or shallow
pits systems manure is stored either long term or
short term below the animal housing area. Gravity and hoof traffic serve as cheap
transport to storage through slats on the floor. The deeper
the pit the less often it will need to be emptied. Shallow pits are often emptied with the
help of gravity to a larger manure storage structure. This deep pit is
designed to store at least one year’s worth of manure. Tie-stall dairy barns collect manure in a gutter behind the cows. A powered
scraper then moves the manure out of the barn. What you see here is the
tail end of a tie-stall gutter system; once out of the building the manure is
either hauled to the field, or to a designated storage area. Freestall barns are the most common housing system for dairy cows; here they have the freedom to move about
the building at will. They can access water and feed, or pick a
stall to rest. Manure is cleaned from the freestall alley using an automatic scraper or tractor
mounted scraper. Floors are claimed at least twice a day while the cows are in the parlor being milked; manure is typically scraped
to the corner of the barn where there’s a flume or cross-channel. As shown the channel is nothing more
than a large concrete gutter running below floor level; this cross
channel is often designed to temporarily store and transport manure. If possible, gravity moves manure out of the barn,
otherwise, a pump will empty the gutter into a storage
area. Manure can also be scraped directly from the barn into a storage area or spreader. Some
freestall alleys are also flushed with water from large tanks located near the barn. The momentum of
the water scours the alley floor and moves manure to the cross-channel,
from there it goes to a separator. The liquid goes back to the flush tanks
for storage and the solids are stockpiled ,and when possible, spread on cropland. Manure storage options. Why store manure? Proper storage will enhance its value,
keep it out of the way until needed, promote cleaner and healthier animals,
and help protect the environment. Storage systems can be constructed out of
concrete, steel, clay, or other synthetic materials to
meet these manure handling and environmental goals. This concrete
storage area can hold more than one year’s worth of liquid manure from the pig barns on site. Other storage
structures are designed to hold manure for only a few weeks allowing more flexibility and timing
of manure application then daily haul systems. The manure from this system can be
loaded into spreaders with the front end loader. This is a
steal storage tank designed for long-term
liquid manure storage. The inside walls are lined with
fiberglass to keep the corrosive manure elements from damaging the metal; they’re generally built above-ground on a concrete slab. Here’s an earthen
basin designed for liquid manure; to help
prevent leakage a liner of dense compact clay is
pounded into the bottom and sides. Clay lined manure storage’s most
economical when suitable clay is available nearby. In less suitable soils, earthen manure
storage can be lined with synthetic materials including rubber, high-density polyethylene, HDPE and polyvinyl chloride, PVC, to prevent
any seepage in the groundwater. Protecting
groundwater is the key to any manure storage structure design and
construction is permitted through the Minnesota Pollution Control Agency. These requirements often include the
installation of monitoring wells to help keep an eye on the integrity of
the storage area. All manure storage areas are not created
equally; different types have different purposes,
which can lead to confusion over manure storage terminology. We’ve
been discussing manure storage structures, ponds and
basins. Lagoons however are not manure storage structures, but are actually manure
treatment systems. Designed to hold four to five times the
annual manure storage volume lagoons are first filled with fresh
water and only about one-quarter of the waste is removed from the system each year. This design and management
promotes microbial activity that helps break down organic matter in
the manure. Solid manure systems often make use of long or short term
storage; temporary or permanent stacking areas
are typically located in fields where it will be spread when the cops
come off. Both temporary and permanent stockpiles are regulated by the MPCA. One type does not fit all operations when it comes to manure
storage the manure’s moisture content and type of bedding play a role, geographic features of the area, as well
as economic considerations, and farmer preferences all make a difference in storage
selection. For instance, clay-lined manure basins will not meet
permitting requirements in karsed areas, clay-lined storage would not be
cost-effective where there is no clay. Where sand bedding
is used systems require a concrete bottom to
allow equipment access to remove all the sand unless it is
settled out prior to storage. Manure storage size varies by need and
producer choice; numbers of livestock, volume of runoff
water, and how often a producer plans to spread are factors that help determine storage
size. Cropping practices and available land for application also play a role. Manure storage structures must be
designed and managed to keep manure out of surface and groundwater. Proper
design and construction helps limit pollution by manure’s nutrients. Good management and equipment upkeep
helps reduce the risk of overflows and accidental spills. Land application. The primary goal of any manure management system is to get
the manure’s nutrients and organic matter back to the cropland in an efficient and
profitable manner. In some systems, particularly liquid
systems with nutrient manure, such as swine finishing, the fertilizer value of the manure
significantly exceeds the cost of application. Getting the most fertilizer value from manure involves knowing the nutrient content of
both the manure and the field it’s being applied to. It’s
also important to know what crops will be planted and have realistic yield goals. Armed with
this information a producer knows how much manure applied
per acre will help to reach yield goals. While stored, different components of manure will
settle out; some solids will sink to the bottom, while others for to the top. Before being taken to the field, stored
manure should be mixed, or agitated. This process
helps shake loose the solids that have settled
and helps provide a more consistent nutrient content throughout the pumping and land application. The next step is to
transport the manure to the field with tanks and tractors, or through pumps and pipes. Liquid manure can be pumped through a
six inch hose more than three miles from storage and applied directly into the ground
where the hose hooks to the tractor. The red arrow shows the hose that runs
from the manure storage directly to the application equipment.
Manure can also be surface applied or sprayed across the ground, but if it sits on the surface too long
much of the valuable nitrogen in the form of ammonia is lost. This method also produces a strong odors
that can linger for days. Turning the manure into the ground as
soon as possible after surface application helps reduce odors and loss of nitrogen.
Next up we’ll look at application equipment that
can eliminate the need for a second pass to incorporate mentor on the field. With a disk incorporation applicator the manure’s pumped onto the surface and
immediately covered. The red arrows show where the manure comes out and the
disks then fold soil over it. Manure can also be
immediately incorporated or injected straight into the ground with what’s
called a sweep injector. The v-shaped tool cuts a 6 inch deep
trench where the manure is pumped, after which
disks behind the sweep close it up again. This is a similar
injection system with disks used to create the trench. If
working properly, these systems leave little or no manure
on the surface. Another type of system pushes tines into
the ground to make shallow holes. Manure is applied on the ground in front
of the tines. This is a low-impact method of
fertilizing alfalfa and pasture, while not really incorporating the manure,
the tines do create shallow holes that act as a repository for the manure.
Solid manure is generally applied on the surface with large spreaders. Shot out from a side, or rear the
application area can be more than 40 feet wide. There is no single best way to land
apply manure, the system must be chosen based on manure consistency, cropping system, available labor, farmer
preference, proximity to waters, land slopes, soil
types and other concerns. Improper land
application of manure can be a significant pollution source for our lakes and
rivers. Thus, it is critical to reduce the risk of
contaminating our natural resources through proper manure handling. This
includes respecting setback distances from tile drains and surface waters and keeping application equipment in
good working order to reduce the possibility of a spill.
Potential odor issues and environmental concerns have some farms treating manure
to concentrate the nutrients and control odor. Concentrating the manure nutrients allows for more economical transportation of the
nutrients farther from the production site. Some treatment systems can generate
electricity by fueling generators with the methane gas produced as manure breaks down. Manure treatment
systems include anaerobic digestion, which produces methane used to generate
electricity, or heat. Aeration encourages the growth
of aerobic bacteria the break down organic
matter in manure and help reduce odor. Composting is
another aerobic system that reduces the manure volume and creates a nearly odor free product
that can be land applied, or sold as a fertilizer for farm and
home use. There are also commercial products
available that can be added to the animal diet, or manure storage to aid in the breakdown of the manure. It’s
unclear how much impact these additives have on the odor
and gas emissions from manure storage. Research is continuing on a variety of
manure treatment systems. Installation of manure treatment systems
is currently driven by energy costs and available land for nutrient
utilization. For more questions on manure handling systems contact your local, or
regional Extension Office, or visit the Manure Management and Air
Quality Program at www.manure.umn.edu