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Forage perfect fit for manure management

New options for manure utilization. Increased forage production. Those are the dual benefits of applying manure to forage, according to a multi-year study from the AgTech Centre in Lethbridge.

“Before this study, surprisingly little was known about how manure application affected forage production and soil quality in Alberta, or about effective application rates and timing,” says Lawrence Papworth, an engineer with the Alberta Agriculture, Food and Rural Development AgTech Centre in Lethbridge.

“The findings show that forage does respond to manure application and that Alberta’s vast tracts of forage land could utilize livestock manure, taking the pressure off cropland in areas where intensive livestock operations are concentrated,” he says. “Applying manure to forage could help the industry better manage manure nutrients and boost forage production at the same time.”

The study began in 1996 with one irrigated alfalfa site near Lethbridge. A second site was added in 1997 near Airdrie, just north of Calgary, using dryland timothy grass. The yield trials ended in 2000 and the final soil samples were taken in the spring of 2001. The experimental design included fall and spring application as well as two manure types and application methods -surface-applied solid cattle manure and injected liquid hog manure. The study also used four different manure application rates and control plots that received no manure.

“Timothy responded after one year of manure application with increasingly higher yields as the application rate increased, though at the highest rate, yields decreased because of lodging,” says Papworth. In 2000, timothy that received no manure yielded a little over 3,000 kilograms of dry matter per hectare, whereas the timothy with the second highest manure application rate yielded close to 6,000 kilograms of dry matter per hectare.

Alfalfa took several years to respond to manure application. “Yield increases were seen, but the application rates did not produce significant jumps in yield,” he says. “Alfalfa fixes nitrogen from the air, so it doesn’t respond to nitrogen contained in manure. We assume the alfalfa was responding to the phosphate and the potassium from the manure, which took some time to build up in the soil.”

In 2000, alfalfa that did not receive any manure, yielded close to 6,500 kilograms of dry matter per hectare, while alfalfa that received manure, yielded around 10,000 kilograms of dry matter per hectare.

Timing, manure type and application method did not significantly affect yields, he says. “But when we began the study, not many people were using manure injection for hog manure, and we were impressed by how it well it works when done properly. Not only does it get the manure into the soil, it greatly reduces odour.”

Applying manure to forage has occurred on some small operations for years. “Small producers will spread manure on their forage and harrow it in,” he says. “But in general, it’s not a widespread practice. Intensive livestock operations would rather apply manure on cropland and till the ground to incorporate it, enabling them to use large volumes of manure. Additionally, liquid injection can be expensive, which is a big reason why it hasn’t caught on for forage.”

With forage crops, the manure has to be spread less intensely than on till ground. “Yet, considering the amount of forage land available, the positive effect manure has on yield and the fact that cropland in some areas is becoming over-fertilized, applying manure to forages is an excellent alternative.”

Papworth does caution that the results from the study are not complete. “We have the yield data, but the soil sample data are still being analysed and interpreted. That will give us the full picture.

“Hopefully, these results will spark interest among producers and help ensure that the valuable nutrients produced from Alberta’s livestock industry are used to their full advantage,” adds Papworth.

A final report encompassing the yield results and the soil data will be finished in the fall of 2001.

The recently renamed AgTech Centre is part of the Alberta Agriculture, Food and Rural Development Agricultural Engineering Branch. The AgTech Centre has expanded its mandate to include all aspects of agricultural sustainability. Producers helped fund the study through the Canada Alberta Beef Industry Development Fund. Other funding was received from the Foothills Forage Association, the County of Lethbridge and the Municipal District of Rockyview.

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