GHGMP Project Reports by Region

Manure injection prescribed for production, environmental issues

Placing manure directly in the root zone makes valuable nutrients available to the crops

The aim of a three-year project that involves directly injecting liquid hog manure into the soil is to demonstrate to Prince Edward Island producers the practice has potential to increase crop yields, reduce input costs and benefit the environment.

The project, launched in 2003 and continuing through 2005, uses blanket injector equipment pulled behind a standard manure tank to inject liquid hog and dairy manure into the soil, explains William MacNeill, a specialist in precision farming practices and P.E.I. field co-ordinator of the federal Greenhouse Gas Mitigation Program (GHGMP). Manure injection is one of the demonstration projects partially funded by GHGMP across Canada.

"The goal is to demonstrate the value of manure injection over traditional broadcast application," says MacNeill, who also farms near O'Leary. "The main drawbacks of land application is the odour produced and the amount of nitrogen lost in the process."

Nitrogen losses

While most producers incorporate manure in the soil after it has been broadcast applied, significant amounts of ammonium nitrogen can still be lost. The average nitrogen loss from manure incorporated within one day is 25 percent, although that increases to about 35 percent if it takes three days to incorporate and up to 50 percent by five days. The nitrogen lost to the atmosphere eventually returns to earth and adds to soil nitrogen levels which, through a process known as denitrification, can be lost again to the atmosphere, this time in the form of nitrous oxide, a harmful greenhouse gas.

With manure injection systems nitrogen losses are reduced to five percent or less.

A liquid manure tank supplied by Agriculture and Agri-Food Canada (AAFC) was outfitted with the Kuhn blanket manure injector in time for limited use in 2003, says MacNeill. "It was a limited trial, but we observed improved barley yields and reduced odour in the demonstration," he says.

Four demonstrations

In 2004 the equipment was used at two sites. In one demonstration, liquid hog manure was injected into the soil to fertilize a potato crop. While in the other project liquid hog manure was injected in late summer into barley stubble after the crop is harvested.

The $11,000 injector tool has nine vibra shank injector teeth, spaced at one-foot intervals. Staggered coulters run ahead of the shanks to cut through crop residue. A leveling harrow at the back of the tool smoothes out ridges and covers any manure left on top of the soil. Liquid manure in the P.E.I. project will be injected at a depth of six to eight inches, depending on the crop.

Nutrient analysis

An important aspect of the project involves soil and nutrient testing to better match manure application rates with crop needs, says MacNeill. "We want to avoid over- application of nutrients," he says. Liquid manure applied at a rate of approximately 3,000 gallons per acre is fairly standard.

"Soil testing and nutrient analysis will tell us if that rate needs to be adjusted," he says. "It may mean little change in the manure rate, but a cut back in the amount of chemical fertilizer."

Demonstration sites will be monitored to evaluate odour reduction, ammonium losses and crop yield. "We're also looking at the economics of injecting liquid manure," says MacNeill. "The injector attachment is a sizeable investment but we'll look at the potential returns from increased yield and reduced fertilizer requirements, as well as opportunity for shared ownership among several producers."

Regional reports will be posted as information becomes available. Please check back regularly for updates.