A report by Jeff Schoenau of the University of Saskatchewan department of soil science and Gordon Hultgren of the Prairie Agricultural Machinery Institute in Humboldt, Sask., has confirmed swine manure can be an effective fertilizer when applied appropriately and at proper rates.
“Application of swine manure to farm fields in Saskatchewan allows a portion of the plant nutrients traditionally exported in feed grains to be recycled back through the system,” said Schoenau.
“But, to maximize the economic benefit of the manure’s nutrients and reduce risk of nutrient contamination of adjacent environments, it is important to get as much of the applied nutrient as possible into the crop.”
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Researchers used examples from work in Saskatchewan to address some of the issues surrounding use of swine manure as a fertilizer.
Their report, Swine Manure as a Source of Plant Nutrients is a building block that could improve understanding of the agronomic value of swine manure, said Karen Bolton, manure management specialist with Pork Central, Saskatchewan’s hog promotion agency.
Schoenau said a challenge of using swine manure is that swine slurry is about 98 percent water. It has a low nutrient content by weight compared to commercial fertilizers.
“That’s why yearly soil analysis is needed in manured fields in order to monitor the effects of the manure application on soil nutrient supplies and balances. Based on this soil analysis, the application rate should be adjusted accordingly.”
Approximate nutrient levels in liquid swine manure can be predicted, but they can be variable. Feed rations, handling, storage time, agitation and pumping depth in the pit can influence nutrient content and form.
Schoenau advises producers to take samples of effluent from the earthen storage unit after agitation and have them analyzed before application.
Swine Manure as a Source of Plant Nutrients refers to several Saskatchewan trials that compared yield response on plots with no fertilizer to those receiving applications of liquid swine manure and commercial urea.
Results showed large yield responses to liquid swine manure on soils with no history of manure application. Overall, low rates of swine manure produced a similar yield response to low rates of urea application.
“Like most fertilizers, it is possible to get too much of a good thing,” the report concludes.
“Therefore, emphasis should be placed on managing manure like any other fertilizer material: using fertilizer nutrient content and soil test/fertilizer recommendation information to calculate rates of application that match the crop’s ability to use the nutrients applied and produce economic yield responses.”
The report is included in Proceedings of Soils and Crops ’98, which will be available this summer through the extension division of the University of Saskatchewan. Copies are also available from Pork Central at 306-787-9112 or from Schoenau at 306-966-6844.
