The spread of manure
By Rosalie I. Tennison
High concentration of manure in some areas leads scientists to search for ways to share the wealth.
No matter how you spread it, manure is frequently in the news and on the minds
of farmers, scientists and the general public. For the public, it is often about
the smell and for farmers it is about how to dispose of it to the best advantage.
For scientists, it is about helping both in a safe, economic and beneficial
way, and in doing so, harnessing the benefits of manure's nutrient value.
Generally, manure is concentrated where there is confined livestock production
and, as the operations become larger, use becomes an issue. The production of
manure on a small grain farm that has a few animals is rarely an issue unless
the issue of water quality is raised by neighbours or municipalities. In the
words of one Agriculture and Agri-Food Canada (AAFC) researcher, manure 'is
a complex issue'.
"My work is concentrated on the best means to use or recover the nutrients
in manure," explains Dr. Katherine Buckley of AAFC in Brandon. "I
focus on the effect of treatment and management of manure on pathogens, ammonia
release and the plant's ability to access the nutrients in manure." In
addition, she also has to consider the transportation of manure to where it
is needed most – a costly prospect given its bulky nature and the cost
Buckley says that on the prairies manure has to be transported great distances
because land near large scale animal production facilities already gets its
full share of manure nutrients. Manure comprises a lot of water, she continues,
which results in the transportation of something that is unnecessary for the
end usage. Her research includes ways to reduce water content of liquid manure
to concentrate the organic materials and nutrients.
"Unfortunately, only large operations can afford the more advanced solid/liquid
separation technologies," admits Buckley. "This issue is more than
just about spreading manure, we need to look at crop management as well. Also,
if we adopt better nutrient management or animal feed, we should be able to
reduce the amount of nutrients excreted by livestock."
Buckley says that improved pasture management could be an answer to reducing
the volume of cattle manure. "If animals are kept on pasture longer, the
nutrients are distributed on the pasture. There may be some advantage in terms
of carbon sequestration to maintaining pasture rather than breaking the land
for feed production. If those animals are fed supplements to improve nutrient
absorption, or feeding is managed so animals are only getting the nutrients
they need, the amount of waste can be reduced."
Back on the feedlot grazing is not an issue and managed feeding does not reduce
waste completely. The concentration of animals in a small area leads to a pile
of manure and all the issues Buckley listed. She says a multi-disciplinary approach
may offer better solutions with animal nutritionists working with animal owners
and those owners working with crop producers, and all following guidelines developed
by several branches of agricultural science.
"The main public concern has been odour created by intensive animal production,"
says Buckley. She points out that the public is concerned about nutrients from
livestock production seeping into ground and surface water in addition to the
smell, with the intensity of the smell considered a contributor of air pollution,
even though the two are not necessarily connected. "It's difficult to determine
where pollutants are coming from, since there is usually not an identified point
source in locations where there are water quality issues. It may not be from
our livestock industry, but good livestock, soil and riparian management practices
should have a positive effect on water quality in the long-term, regardless
of the source of the problem."
Buckley and her colleagues are attempting to identify and quantify the effects
of better manure management practices by participating in research projects
in various locations across the country. She reminds Canadian farmers that all
regions are different and a solution for one area may not work elsewhere due
to differences in climate and soil characteristics. For example, she says that
while only a small percentage of crop land in Manitoba receives manure, there
are surpluses of phosphorus applied in a few localities in the province. This
surplus is due to a mismatch between the amount of phosphorus in manure and
the ability of the crop to make full use of this nutrient when manure is applied
as a nitrogen fertilizer. Research investigating new management practices and
new technologies to balance manure nutrient inputs to soil and improve soil
quality will assist in capturing the full value of manure.
So far, a reasonable alternative for dealing with manure is by composting to
reduce the volume and concentrate the nutrients, but the cost may be prohibitive
for small operations. In order to ensure proper plant nutrition, the manure
needs to be tested for nutrient levels and no two batches of manure are likely
to have the same analysis. But how can highly concentrated animal operations
share the wealth more easily?
Dr. Frank Larney of AAFC in Lethbridge has been working with feedlot owners
on ways to manage feedlot manure. But again, the problem is transportation.
"It's just not economical to transport manure, so it is applied on fields
close to the feedlots which creates a high concentration on certain areas on
an annual basis. Reducing the water content through composting makes the transportation
of the manure more economical." The composted material is welcomed on potato
acres because it adds organic matter and nutrition. Another benefit of composting
is that few weed seeds are returned to the soil, which is not the case with
the raw product.
"Without a doubt, the compost model is the most successful way to manage
manure," says Larney. Another idea for using manure is bio-gas, he says,
but that technology is not perfected yet and the cost/benefit has to be determined.
"Ultimately, the greatest problems with manure are concentration and distribution,
and we need to find economical ways to spread it around."
The work to find a solution on how to best use our manure nutrient resources
is far from done and, while the multi-disciplinary approach may be the best,
it will take some time yet before a definitive, economical and practical solution
is found. In the meantime, producers should heed the best science available
today, as recommended by the provincial government's Beneficial Management Practices,
and as required by provincial and municipal requirements, such as Alberta's
Agricultural Operation Practice Act (AOPA). -30-
Manure management: Where's the crisis?
High concentrations of manure may only
be an issue in pockets of the country.
Mention greenhouse gases, an over-abundance
of manure, and contaminated water and folks start looking for the nearest farm.
While feedlot owners and scientists search for ways to effectively dispose of
manure, there may not be a crisis of over-abundance at all. In fact, the crisis
is one of distribution.
Dr. Adrian Johnston of the Potash and Phosphate Institute of Canada in Saskatoon
has an interest in manure. It can provide a valuable source of phosphorus, if
an economical way can be found to harness the nutrient. He admits there are
problems with manure used as a sole source of crop nutrition, but it remains
a viable nutritional source if used properly. He is more concerned about the
errors in reporting on the seriousness of manure over-abundance.
"There are problems with manure, but how many acres actually receive manure?"
Johnston asks. In a survey question posed by Statistics Canada in the 2001
Census of Agriculture, it was found that only two percent of the crop and
fallow growing acres in Saskatchewan receive applications of manure. The percentage
increases to five percent in Manitoba and Alberta.
He points out that rangeland was not considered because the manure is never
recovered on these grazing lands. Also, the distance of rangeland from high
concentrations of manure make transportation and spread of excess on the rangeland
cost prohibitive in most instances, even though it may be useful.
Certainly, according to Johnston, many more acres could have manure spread
on them. In fact, research work in Alberta found that the greatest economic
value from manure application was when it was applied to soils which had not
previously received manure. Unfortunately, the census does not make clear how
far the manure would have to be transported to reach the acres that could use
It appears, based on the census data, that the Canadian prairies have concentrated
pockets of manure in a sea of phosphorus deficient soils. However, areas with
high concentrations of feedlots or intensive animal production are in a surplus
position. What needs to be discovered is how to spread the benefits of manure
nutrition around to those 60 to 80 percent of prairie soils which are deficient
in phosphorus. -30-
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