Solid hog and cattle manures release nitrogen slower than many farmers have assumed.
Research at the University of Manitoba has found that much less than the 25 per cent release cited in government publications is actually available to crops in the first year after solid manure is applied.
“After six years of annual applications of solid pig and dairy manures at high rates, the cumulative efficiency of all the solid manure N (organic plus ammonium N) was only five percent to seven percent,” the scientists concluded in a paper summarizing their research.
Trevor Fraser, a University of Manitoba soil fertility technician, said using the measuring sticks of nitrogen and yield, solid manures performed poorly in field trials at the Glenlea Research Station south of Winnipeg.
“The liquid pig manure applied for both annual and perennial crop rotations did very well. It was almost the same as synthetic fertilizer,” Fraser said.
He said the solid pig and cattle manures were hardly releasing any nitrogen.
But they do have other benefits, such as phosphorous and potassium and organic matter to improve soil structure.