LLOYDMINSTER — Recent trials show some forages could help fix more nitrogen and possibly reduce animal methane emissions, while also increasing weight gain.
The possible benefits largely depend on pasture management, soil type and weather, explained Bart Lardner, an animal and poultry science professor with the University of Saskatchewan, speaking at the Agri-Visions conference in Lloydminster on Feb. 14.
Lardner said trials from 2010-13 in Saskatchewan found alfalfa and red clover could fix large amounts of nitrogen into the soil.
He said alfalfa did particularly well in the black-soil zone of northeastern Saskatchewan, providing 150 to 200 pounds of nitrogen per acre after it was grown for two straight years.
“Alfalfa did well there in providing nitrogen, leaving lots available for the subsequent crop.”
He said red clover did well in the thin-black (Lanigan, Sask.) and dark brown (Saskatoon) regions, offering fertilizer equivalents of 100 to 125 lb. per acre after being grown for two years.
“The benefit of that is it saves on the purchase of nitrogen and urea. It’s an organic form of fertilizer,” he said.
“Thinking about the use of legumes in rotations is so, so important.”
In a separate study, researchers determined some forages could potentially reduce animal methane emissions while also possibly increasing their gain.
They undertook sod-seeding, a practice in which researchers planted cicer milkvetch and sainfoin into existing pasture stands, to determine such benefits.
Lardner explained sod-seeding trials from 2015-18 in Lanigan and Lethbridge were done in a way to suppress existing pasture species rather than fully decimating them.
He said Lanigan trials found methane levels were lower when cattle grazed cicer milkvetch.
The animals also had increased gains when grazing on sod-seeded cicer milkvetch and sainfoin, he added.
“They gained better than on the non-seeded pastures,” he said.
“The legume itself is improving the quality of the pasture. Introducing that legume in the pasture is one way of increasing quality of the pasture and also increasing gain and reduced methane.”
To get their results, researchers applied 0.5 litres of glyphosate to suppress existing pasture species, later sod-seeding sainfoin at 23 lb. per acre and cicer milkvetch at 15 lb. per acre.
Sod-seeding was done with an AgroPlow.
Lethbridge trial data was unavailable.
Lardner explained sod-seeding is cheaper than breaking and re-seeding, providing producers with an alternative.
He said costs to break and re-seed can be around $300 per acre, while sod-seeding the trial forages ranged from $25 to $30 an acre.
“The idea is not only to reduce emissions, but to sequester carbon.”
He said timely rain in Lanigan helped with the favourable results.
“We were very lucky,” he said.
“We sod-seeded in June, when it was dry, but then it rained a lot in July. If it rains, it really does help you be successful. Some legumes we seeded were going into full bloom in the fall.”