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New information on forage manure application for beef producers

Recent research into forage manure application has resulted in information that will give beef producers confidence in using the practice as a manure management option, without sacrificing soil and forage quality, or crop yield in Alberta.

Alberta's beef industry generates a large amount of manure that must be managed in a responsible way, says Lawrence Papworth, an engineer with Alberta Agriculture, Food and Rural Development (AAFRD). Producers often apply manure to cultivated land, but in cases where this land is unavailable, the manure is applied to forage land. However, there has been little research on the effect of this practice on soil chemistry, forage quality and yield.

"We wanted to study the long-term feasibility of applying manure to forage crops," says Papworth. "Even though some producers were applying manure on forages, they didn't have good information about the effects of that practice. However, done properly, this practice creates greater potential for beef industry growth because the practice can be viewed as a sustainable manure management option."

The in-depth five-year study examined the effects of solid beef and liquid hog manure on forage land. The cattle component was funded in part by the Canada Alberta Beef Industry Development Fund (CABIDF).

"We found that beef manure application affects soil properties, and forage yield and quality, but it also provides an additional benefit to beef producers searching for further manure management options that allow them to remain profitable, productive and environmentally responsible," says Papworth.

Researchers used two research sites - one near Lethbridge, Alta. and another east of Airdrie, Alta. The Lethbridge site consisted of irrigated alfalfa while the Airdrie site was seeded to rain-fed Timothy grass. At the beginning of the study, researchers collected soil samples from both sites to a depth of 1.5 metres and subsequent samples were collected every spring during the five-year study.

"We surface applied solid cattle manure at both sites in the spring and fall of each year," says Papworth. There were five different application rates: 0, 31, 61, 92 and 122 Mg/ha on a wet-weight basis.

"In analysing the soil, we wanted to determine if there was a buildup of nutrients and if those nutrients were leaching through the soil profile," says Barry Olson, an AAFRD soil research scientist who collaborated with Papworth. "We examined the nutrient status of the soil - including crop available nitrogen (N) and phosphorus (P), as well as soil salinity."

At higher manure application rates, soil N, P, and salinity increased. Higher levels of P in soil are cause for environmental concern. That's why producers should use a low manure application rate and regularly test soil to ensure they're not over-applying and creating a significant nutrient buildup, says Olson.

Forage material was analysed for 16 tissue-quality parameters, including protein and acid detergent fibre. In both crops, manure application increased almost all of the parameters measured, but the dietary significance of those increases was not examined in this study.

The third component of the research examined how manure application rates affected crop yields. Researchers noted higher yields following manure application, with the exception of the 122 Mg/ha rate. In that case, yield was lower than the control. "This may indicate that the higher application rate caused a yield depression," says Papworth.

"Still, nothing in our research indicates that producers shouldn't apply manure to forages," he adds. "They just have to ensure their annual application rates are appropriate. Rates shouldn't exceed the lowest rates used in our research, 31 Mg/ha on a wet-weight basis. This, or even lower rates, ensures soil nutrient levels are maintained at appropriate levels and minimizes yield suppression and environmental risks from higher application rates."

Surface-applying beef manure to forage crops provides a nutrient benefit to the crops and can be a sustainable manure management practice for Alberta's beef producers. However, Olson urges producers to be cautious about surface-applied solid manure; more care needs to be taken to prevent runoff losses and possible contamination of surface water bodies. In Alberta, manure application is legislated by the Agricultural Operation Practices Act (AOPA).

CABIDF is a joint $16.4 million fund of Alberta Agriculture, Food and Rural Development and Agriculture and Agri-Food Canada. The Fund is administered by Alberta Beef Producers and has supported more than 50 projects in five major categories identified to benefit the Alberta beef industry.

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