A new study provides encouraging news about how repeated swine manure applications affect crop production, soil and environmental quality in Saskatchewan.
Results show that manure applied at agronomic rates is a sustainable management practice. The rate of application must be in balance with crop nutrient needs.
Jeff Schoenau, soil scientist at the University of Saskatchewan, is the lead scientist on the research project.
“Our intent was to develop guidelines and recommendations as to how the nutrients and organic matter in manures are best utilized in an agronomic and environmentally sustainable manner,” said Schoenau.
Read Also
VIDEO: Green Lightning and Nytro Ag win sustainability innovation award
Nytro Ag Corp and Green Lightning recieved an innovation award at Ag in Motion 2025 for the Green Lightning Nitrogen Machine, which converts atmospheric nitrogen into a plant-usable form.
“We have in place four long-term manure research trial sites across Saskatchewan where we are looking at different rates, sequences and methods of application of manure.”
The scientists measured soil properties including nutrient content, organic matter, soil structure, crop yield and quality. Teams worked mostly with hog manure, but also with cattle manure.
“We found that when manure is applied at agronomic recommended rates, which may be accomplished by manure testing and soil testing to determine the appropriate rate and balance of manure and fertilizer nutrients to meet the crop demand, we see no evidence of nutrient loading or any negative effect on the quality of the soil.”
There is a caveat to this finding, however.
“We do see evidence of nutrient buildup, increased losses by leeching or denitrification, in situations where agronomic rates are exceeded. Respecting agronomic rates is also key to good yield responses to the nutrients contained in the manure over sustained periods.
“When manure is overapplied, we do see negative effects like lodging where the crop falls over and injury to germinating seeds and seedlings due to excessive salts and ammonium.”
Schoenau’s team confirmed that the method of application is also important in achieving the best nutrient recovery by the crop.
“We found that with injected liquid manure, we consistently achieved better crop recovery of nutrients and yields, which is the most desirable outcome, than with surface broadcast applications. This liquid injection of manure into the soil as bands was achieved during our trials with the help of a low disturbance coulter injector system.
“The system was incorporated by Prairie Agricultural Machinery Institute on their swine manure injector truck, used for manure application research and demonstration purposes. Similar approaches to manure injection are now being utilized by commercial applicators.”
The study showed annual applications of manure made for five to eight years on these soils at agronomic rates, in balance with crop nutrient removal, greatly enhanced crop production while maintaining or improving soil and environmental quality.
The study was funded by Saskatchewan Agriculture’s Agriculture Development Fund.
