Manure additives can lower nitrogen loss and increase crop yields

Hog farmers can reduce winter nitrogen loss and increase crop yields by applying an additive to swine manure before spreading it on their fields. A research project funded through the Farm Innovation Program evaluated two different manure additives for their ability to slow nitrogen conversion and minimize nutrient losses from leaching and denitrification, which can affect ground and surface water and increase production costs for farmers.

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How was the research conducted?
Researcher Bonnie Ball, a soil fertility specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs, lab and field-tested two products: ammonium thiosulfate (ATS), a commercially available liquid fertilizer material that slows conversion of ammonium to nitrate, and Biochar, a bio-industry by-product that enhances carbon storage.

What did the research show?
In the lab setting, both ATS and Biochar reduced nitrogen mobility when they were added to the soil as manure additives. In field trials, Biochar was effective in controlling manure odour, increased manure’s viscosity and doubled its dry matter content. Wheat yields showed an increase of approximately 10 bushels per acre in one of two sites where Biochar was added to fall-applied manure, and there was a reduction in the movement of nitrates to ground and surface water. There was no yield response where ATS was used and no evidence of measurable decrease in nitrogen release.

What does this mean for farmers?
• Potential yield increase. “At today’s price of wheat, the yield increase could make an impact on profitability and would certainly cover the cost of trucking the additive,” notes Ball, although cautioning that study results are based on only one year of data.
• Odour reduction. “Depending on a farm’s location, this can be a very valuable benefit,” says Ball. “Blowing this on top of a manure pit could be a convenient way to put the additive into the manure and control odour at the same time.”
• Decreased nitrogen leaching. “Reducing the liquidity of the manure can be especially valuable in fields where preferential flow to tile is a problem,” suggests Ball, as it reduces the contamination of surface water from manure flowing directly into the tile. Decreased nitrogen leaching can also preserve drinking water quality and reduce the need for additional fertilizer application.
• More with less. “It’s a definite environmental benefit if we can apply less nitrogen and phosphorus to the soil and get the equivalent response,” says Ball.

Where can I get more information?
More information on this research is available from Ontario Pork at www.ontariopork.on.ca. 
 

The Farm Innovation Program (FIP) was funded in part through Growing Forward, a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of several Growing Forward programs in Ontario.