GHGMP Project Reports by Region

Liquid manure banding benefits forage production

B.C. producers have improved manure handling option

Ongoing research in B.C. is providing farmers with the know-how to use higher rates of manure in an economical and environmentally sustainable manner to produce forages, says a long-time researcher with Agriculture and Agri-Food Canada (AAFC).

Multiple manure applications during the long Lower Mainland growing season can produce good forage crops without negative social and environmental effects, says Dr. Shabtai Bittman, a cropping systems specialist with the AAFC Pacific Agri-Food Research Centre in Agassiz.

"Our research since the early '90s has involved several problem-solving steps," says Bittman. "And we're getting much closer to having a practical, economical and sustainable system producers can use." The research project, co-ordinated through the Pacific Field Corn Association, is supported in part with funds from the federal Greenhouse Gas Mitigation Program for Canadian Agriculture (GHGMP).

Fine tuning research

Bittman's research is fine-tuning a system using minimum soil disturbance and a manure application tool that bands narrow strips of manure directly onto the soil surface. The tillage/aeration tool increases soil/manure contact improving infiltration of liquid manure, reducing odour and optimizing nitrogen use. While the application system works well for nitrogen, the next step is to better manage nutrient loading to reduce the amount of phosphorus being applied.

The challenge has been to develop a system that uses relatively high rates of liquid hog and dairy manure as primary nutrient sources for hay and pastureland, while at the same time reducing odour and minimizing environmental impacts.

"The key is to make this economical and practical," says Bittman. "Using manure effectively has to make practical sense to producers."

Increased use of manure as a crop nutrient source also needs to minimize environmental impacts. If high rates of manure are applied under wet conditions, there's a risk of surplus nutrients being leached from the soil, or of nitrogen being lost to the atmosphere through denitrification or volatilization. Denitrification releases nitrous oxide, while volatilization releases ammonia to the atmosphere. Both contribute to greenhouse gas emissions directly and indirectly.

Critical for B.C.

More efficient use of manure is critical in B.C.'s south coastal region where intensive agriculture - dairy, hog, poultry and to a much lesser extent, beef operations - produce high manure volumes that are to be used on a limited land base.

"By Canadian, as well as international standards, the Lower Mainland has a high agricultural density which means a high volume of manure," says Bittman. "It's definitely not insurmountable, but it has to be managed. We need to find ways to make the most efficient use of manure, while minimizing the environmental impact."

One option is to develop a practical system that makes greater use of liquid manure in forage production. Manure has routinely been used more on annually cropped land such as corn. Usually it is applied in the spring and incorporated with a tillage operation prior to seeding. Producers apply less manure to forage crops for several reasons. Broadcast application with a standard liquid manure tank equipped with a splash plate will produce inconsistent forage production results, smother crops, cause odour, increase nitrogen losses to the atmosphere, cause soil compaction, damage swards and decrease the potential livestock feed palatability.

The tool that makes liquid manure application in forage crops feasible is called a sleighfoot manure applicator (SMA). The SMA, which mounts on the back of a liquid manure tank, was developed in Holland and introduced to British Columbia in demonstrations organized several years ago by the Abbotsford-based Dairy Producer's Conservation Group.

Liquid manure from the tank is distributed along a pipe mounted at the back of the tank. The pipes come in a range of widths. Suspended along the pipe are a series of tubes that hang down into the forage crop canopy. At the end of each tube is a foot, or sleighfoot-designed outlet, which trails along the ground distributing a band of manure on the soil surface underneath the canopy and surface residue.

The down tubes along the 20 to 30-foot wide pipe are spaced an average of nine inches (eight to 12 inch range) apart. The system has been tested extensively in B.C. for several years.

Major improvement

"We've found it is a considerable improvement over broadcast application methods, especially in forage crops," says Bittman. The system provides uniform manure application and a consistent level of nutrients for the crop; it dramatically reduces odour; ammonia losses are reduced by up to 50 percent; and it greatly expands the manure application window.

Instead of a single annual manure application on crop land before seeding, the SMA makes it possible and desirable to make repeat manure applications during the forage crop growing season. With up to six hay and silage cuts during the year, producers can make four or five manure applications, one after each cut.

To further enhance nutrient uptake by the forage crop and reduce nitrogen loss, researchers at the AAFC research centre in Agassiz combined the SMA with an aeration tool behind the liquid manure tank. The aerator teeth break the soil surface increasing soil/manure contact, says Bittman. The combination tool, the Aerway SSD, which is now marketed commercially by Holland Equipment Ltd., eliminates the need for commercial fertilizer in forage crops.

"Research shows the system can be used for repeat applications over the growing season to ideally supply up to 550 kilograms of nitrogen per hectare for the forage crop," says Bittman. "That is a sustainable level. It meets crop nutrient requirements, while at the same time minimizing the risk of nitrogen being leached from the soil or lost to the atmosphere."

Phosphorus issue

The next problem to be solved in the manure application puzzle is phosphorus loading, says Bittman. Liquid dairy and hog manure have high levels of phosphorus relative to nitrogen so that application of phosphorus may exceed crop requirements.

Since most phosphorus is contained in manure solids, the next research step is to look at economical ways to separate liquid and solid components. Settling ponds, mechanical liquid/solid separators, and even barn floor designs that separate liquids and solids at the point of production, are among the options.

"The type of system used will likely depend on the size of the farming operation," says Bittman. "But if we can find a way to economically and practically separate the liquid component, which contains most of the nitrogen, it can be safely applied to forage crops. The solid component can be more easily managed with other methods such as composting."

The drier solid manure can be more economically transported greater distances to be used on a larger land base.

"The system using liquid manure on forages increases the opportunities for producers to improve manure management," says Sandra Traichel, co-ordinator with the Abbotsford Soil Conservation Association and the southern B.C. field co-ordinator of the GHGMP. "This strategy could benefit the crop, reduce input costs and minimize the social impact associated with manure handling,as well as reduce the amount of greenhouse gas emissions produced through manure management."

As a further benefit to producers, if they can apply more manure through the growing season it means they could head into fall and winter with empty manure storage facilities. That means the system could reduce the amount of manure storage required on farms.

More information on the GHGMP is available on the Soil Conservation Council of Canada Web site at www.soilcc.ca.


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