A study of manure application to eroded soil shows manure can contribute to crop yield increases 16 years later.
“One-time application of manure had long-lived residual effects,” said Frank Larney of Agriculture Canada’s research centre in Lethbridge, who reported research findings Jan. 17 to the Manure Management Update conference.
“There’s lots of land out there that can benefit from manure in terms of restoring productivity to eroded soil.”
Research he conducted with researcher Henry Janzen on “simulated erosion” sites established 21 years ago involved topsoil excavation at zero, five, 10, 15 and 20 centimetre depths.
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They then applied nitrogen and phosphorus fertilizer, topsoil and feedlot manure to the plots and continuously planted them to spring wheat using zero till. Irrigated and dryland plots were studied.
Examination of results in 2001 showed crop performance was highest on the plots that received a onetime manure application, followed by those amended with topsoil and then those with fertilizer.
Crop yields were lower as the level of erosion increased, but manure helped mitigate the losses.
“For example, on the 10 cm cut, grain yield increased 73 percent with manure, 38 percent with topsoil and 28 percent with fertilizer,” said the conference report synopsis.
Results were better on the 20 cm cut, where the manure plot increases were 158 percent compared to 89 percent with topsoil and 40 percent with fertilizer.
Larney updated the findings in 2009 and found the manure was still contributing to land productivity.
“Amendments still ranked manure-topsoil-fertilizer in terms of restoring productivity to the desurfaced soils. These results showed that a single application of manure at a modest rate at the beginning of the study contributed to significant yield responses some 16 years later,” said the research report.
Larney told the conference that the residual effect of manure also increased as the depth of erosion increased. This was true on dryland and irrigation, although the response on the irrigated land was lower.
“It is better to apply manure to more severely eroded areas of the landscape because that’s where you are going to get your best response,” he said.
Climate change may worsen the problem of erosion worldwide because of changes in soil moisture levels and precipitation, he said.
Manure might become even more important in restoring soil productivity because eroded soil is poor at storing carbon and pulling carbon dioxide from the atmosphere.
Manure increases organic matter in the soil and assists in aggregation, so soil particles are better able to stick together.
As well, phosphorus in manure is readily available to plants, while the fertilizer form can be immobilized in chalky soil.
Larney also reported results of research on using manure to restore oil and natural gas well sites.
Best results were achieved with manure as a replacement for topsoil, assuming the former topsoil was no longer available.
“These studies demonstrate a win-win situation for using manure or compost generated by Alberta’s livestock industry to restore productivity to eroded soils,” he said.
“Also, manure … can be used directly or as compost to help the oil and gas industry meet its goal of judicious land reclamation.”
