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.
