by Barb Baylor Anderson
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A modified greenhouse design holds
particular appeal for the Pacific Islands, where expensive commercial
fertilizer can be replaced with composted hog manure.
Photo by Jerry DeWitt |
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Producers in Hawaii are exploring a
different approach to manure and nutrient management that employs a
dry litter technology. The system, imported from land-limited countries
like the Netherlands, Japan and Taiwan, could help producers effectively
manage livestock waste, especially since Hawaii producers contend with
more expensive land and bedding costs. Moreover, Hawaiians face truly
unique ecological issues.
“Animal manure can be processed and
developed as a marketable organic soil amendment for the agricultural,
garden and landscape industries,” reports researcher Glen Fukumoto with
the University of Hawaii Cooperative Extension Service. “The interest
in organic products is creating opportunities for innovators of nutrient
management.”
Dry litter systems must be adapted
to work in the tropics because excessive heat, disease and parasite
build-up in litter are common. With funding from SARE, university researchers
have worked to adapt the dry litter system to the state. The work began
with a demonstration on an intensive 10-acre pig farm/ orchard and market
garden at 1,600 feet altitude. There, the lava is thinly covered with
erodible soil that has low nitrogen and organic matter content – and
could benefit from nutrient-rich compost.
The modified dry litter system that
has evolved from the research combines animal manure with shredded green
residue from orchards, market gardens and landscape operations to produce
compost. Dry litter systems also reduce or prevent non-point source
pollution by eliminating the use of water to clean hog production facilities.
“Elimination of water in the system
removes the possibility of pollution from various components of a typical
confined feeding operation waste management system,” said Fukumoto.
The key to the system is sloping pen
floors that through a pig’s hoof action propel the litter material out
of the pen and into a holding trench. The carbon-nutrient mix flows
out of the pens, and the separate composting trench keeps hogs from
exposure to pre-compost material, where diseases and parasites may develop.
This separation is the key difference in the modified design. Masazo's
Pig Farm on the southern point of the Big Island of Hawaii has used
the modified dry litter system since 1996 to collect and compost manure
from 30 to 40 sows.
Masazo's owners, Dane and Terri Shibuya,
constructed a modified greenhouse structure with two sets of pens for
sows in different reproductive stages. Their system, which contains
no mechanical parts or specialized equipment, provides cover and protection
for the animals while collecting manure in a pit. After mixing the manure
with carbonaceous material, they spread the compost on bananas, ti leaves
and taro in their fields.
Cost analysis shows initial construction
at approximately one-fourth the cost of a typical system in Hawaii.
In addition, dry litter systems have lower operational, maintenance,
labor and water costs, and may avoid potential water pollution fines
and legal costs emanating from odor complaints.
One of the greatest benefits is the
potential for economic return from the compost. When the litter compost
was applied to market garden bananas in the initial demonstration, for
example, researchers measured savings of $201 per acre.
“The modified dry litter
system concepts may be adapted to larger, temperate ecosystems utilizing
the hoop-type structures,” said Fukumoto. “The dynamic flow of animal
and green waste streams eliminates composting heat in pens and reduces
exposure to disease and parasites. Ultimately, the value-added nutrients
generate either a new revenue stream or fertilizer savings for the integrated
farm.”
For more in-depth information
about this system, please see:
The Modified Dry Litter Waste Management System
Hawaii Cooperative Extension Service
http://www2.ctahr.hawaii.edu/sustainag/dry_litter.htm
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