To identify the more emission friendly type of manure and the more emission friendly way to apply it researchers with the University of Saskatchewan have been comparing applications of solid swine, feedlot and poultry manure and liquid swine and dairy manure.

Manure was applied using a prototype solid manure injection system developed by the Prairie Agricultural Machinery Institute on some plots and on others manure was hand applied to simulate broadcast and injected liquid manure application.

Joy Agnew, a graduate student with the Department of Agricultural and Bioresource Engineering, says, with new carbon reduction targets being set, we need to be more aware of how manure application practices will affect greenhouse gas emissions.

Joy Agnew-University of Saskatchewan

So far we've seen that liquid manure produces 50 percent higher odours and 80 percent higher greenhouse gases than solid manure.

As for the injection versus the surface application, we saw that the overall odor emission was decreased by 20 percent due to injection but, when you break it down between liquid and solid manure, injection actually slightly increased odours from liquid manure and this is probably due to pooling of manure on the surface at high application rates.

Injection of solid manure reduced odours a little bit more consistently and provided an overall reduction of odours of 40 percent.

Injection of manure actually increased greenhouse gas emissions by more than 40 percent in both cases.

Both liquid and solid manure resulted in an increase of greenhouse gas emissions.

Agnew says that's probably due the anaerobic conditions underneath the soil.

She notes microbes that degrade the manure beneath the soil actually emit more toxic greenhouse gases than the aerobic microbes that degrade the manure on the surface.