winter losses – Livestock and Poultry Environmental Learning Community

There is growing evidence that soil nutrient cycling is sustained during the non-growing season in the northern regions of Canada. However, the extent of the transformations and loss of fall-applied manure N is not well documented. The NH4-N fraction of liquid dairy cattle manure, liquid swine manure, and ammonium sulfate was enriched with 15N radioactive isotope, and all N sources were applied to bare sandy loams in early November at sites located in contrasted climate (mean annual temperature 1 to 10°C; mean annual precipitation 300 to 1300 mm; mean snow cover depth <5 to 70 cm). The experiment was replicated over two years at each site. Soils were sampled on the week of application, in November, and at intervals until next May. The recovery of applied 15N in soil NH4-N, NO3-N and organic N pools was measured in the 0-30 cm depth. Soil temperature was also monitored at the 5, 20 and 50 cm depths. Although the transformation of applied ammonium was delayed in colder areas, the transformation of 15NH4-N was generally completed by April, generally before seeding of the next crop. Both nitrification and immobilization of fall-applied 15NH4-N occurred throughout the non-growing season at all sites. As a result, residual 15N was essentially recovered as NO3-N and organic N in the following spring. In most cases, more than 50% of fall-applied 15N was not recovered in the following spring. In general, more 15NH4-N was immobilized with manures than ammonium sulfate, possibly because of the presence of fresh carbon in the manure. As a result, more 15N was recovered in the spring with the manure, and this was particularly obvious at the warmer sites. We conclude that a significant portion of fall-applied NH4-N may be lost during the non-growing season, even in areas with cold and long winter period.

Purpose

It is now recognized that biological processes involved in nitrogen (N) cycling are sustained in agricultural soils under frozen conditions (Clark et al., 2009; Maljanen et al., 2007; Virkajärvi et al., 2010), and that a significant portion of N present in soils in the fall may be transformed and lost during the non-growing season (Jayasundara et al., 2010; Chantigny et al., 2014). However, the extent to which fall-applied N fertilizer, and especially manure-N, can be lost as a function of local winter conditions (e.g. snow cover depth, frost penetration) is not known. Climate models are currently predicting that global warming will result in reduced snow fall, deeper frost penetration and more freeze-thaw cycles in soils of North America (Henry, 2008). This will have impacts on soil biological processes (Groffman et al., 2001), but it is not possible to predict how it may influence the fate of fall-applied N. Our objective was to use a multi-site approach to determine the extent of transformation and loss of fall-applied N during the non-growing season under contrasted winter conditions.

What did we do?

Pig slurry and dairy cattle slurry were enriched with 15N by adding a small amount of ammonium sulfate (99 atom% 15N). This approach allowed tracing of the readily available fraction of manure N (ammonia-N) in the soil N pools. Ammonium sulfate labelled at 5 atom% 15N was also included in the experiment as a no-carbon control treatment. The three treatments were applied to bare loamy soils (top 10 cm) in late fall (first week of November) at four sites located in different climatic zones of Canada: Pacific Maritimes [Mean annual temperature (MAT), 10.5°C; Mean annual precipitation (MAP), 1755 mm; average snow depth (ASD), < 1cm]; Prairies [MAT, 5.7°C; MAP, 383 mm; ASD, 3 cm]; Mixed Wood Plain [MAT, 6.3°C; MAP, 914 mm; ASD, 13 cm]; Boreal Shield [MAT, 4.2°C; MAP, 1213 mm; ASD, 44 cm]. The experiment was repeated in 2009-10 and 2010-11 at all sites. Soils were sampled to 30 cm depth on the week of application, and at intervals until early May to determine the amount of manure N recovered in the NH4, NO3 and organic (immobilized) N pools, as a function of time since application.

Overwinter transformation and fate of fall-applied manure nitrogen

What have we learned?

Fall-applied N was transformed and lost throughout the non-growing season at all sites (Fig. 1). Losses were rapid at the warmest site (Pacific Maritimes), and more gradual at the other sites where colder soil temperatures were recorded. Yet, six months after application (late April – early May) only 10 to 50% of fall-applied 15N was recovered in the top 30 cm of soil suggesting very significant loss of manure N during this period. Immobilization and nitrification of applied 15NH4 occurred throughout the non-growing season at all sites (data not shown), and 15N recovered in the next spring was essentially present as NO3 and organic N. At two sites, a greater proportion of applied 15N was recovered in the spring with the manures than ammonium sulfate, and more of this residual 15N was in the organic form in the manure treatments. This suggests that carbon present in the manure stimulated immobilization and retention of fall-applied N in soil. Overall, the results indicate that the readily available fraction of fall-applied N is at high risk of loss during winter, and that changes in soil conditions induced by global warming may not have a great influence on this process or on the manure-N transformation during winter.

References

Chantigny M.H., Angers D.A., Rochette P., Pomar C., Pelster D.E. 2014. Evidencing overwinter loss of residual organic and clay-fixed nitrogen from side-dressed, 15N-labelled pig slurry. Can. J. Soil Sci. 94:1-8.

Clark K., Chantigny M.H., Angers D.A., Rochette P., Parent L.E. 2009. Nitrogen transformations in cold and frozen agricultural soils following organic amendments. Soil Biol. Biochem. 41:348-356.

Groffman P.M., Driscoll C.T., Fahey T.J., Hardy J.P., Fitzhugh R.D., Tierney, G.L. 2001. Colder soils in a warmer world: A snow manipulation study in a northern hardwood forest ecosystem. Biogeochemistry 56, 135-150.

Henry, H.A.L. 2008. Climate change and soil freezing dynamics: Historical trends and projected changes. Climatic Change 87, 421-434.

Jayasundara, S., Wagner-Riddle, C., Parkin, G., Lauzon, J., Fan, M.Z. 2010. Transformations and losses of swine manure 15N as affected by aopplication timing at two contrasting sites.

Maljanen M., Kohonen, A.R., Virkajärvi P., Martikainen P.J. 2007. Fluxes and production of N2O, CO2 and CH4 in boreal agricultural soil during winter as affected by snow cover. Tellus, Series B: Chem. Phys. Meteor. 59, 853-859.

Virkajärvi P., Maljanen M., Saarijarvi K., Haapala J., Martikainen P.J. 2010. N2O emissions from boreal grass and grass-clover pasture soils. Agric. Ecosyst. Environ. 137, 59-67.

Future Plans

Now that we evidenced the significance of losses of fall-applied N from soils during the winter period under varied climatic conditions, we are initiating field work to determine best practices for fall application of manure (e.g. early vs. late fall application; use of additives to delay nitrification of manure ammonia) that will mitigate losses and help efficiently transferring applied N to crop in the next spring.

Corresponding author, title, and affiliation

Martin H. Chantigny, Soil Scientist, Agriculture and Agri-Food Canada, Quebec

Corresponding author email

martin.chantigny@agr.gc.ca

Other authors

Frank J. Larney, Agric. and Agri-Food Canada, Lethbridge; Shabtai Bittman, Agric. and Agri-Food Canada, Agassiz; David Lapen, Agric. and Agri-Food Canada, Ottawa; Denis A. Angers, Philippe Rochette, Agric. and Agri-Food Canada, Quebec

Additional information

Scientific papers and reports can be accessed through my webpage: www.agr.gc.ca/fra/science-et-innovation/centres-de-recherche/quebec/centre-de-recherche-et-de-developpement-sur-les-sols-et-les-grandes-cultures/personnel-et-expertise-scientifiques/chantigny-martin-phd/?id=1181933396583

Acknowledgements

This project was financially supported by the Sustainable AGriculture Environmental Systems (SAGES) Initiative of Agriculture and Agri-Food Canada

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

Why Study Nitrous Oxide Emissions and Manure Application?*

It is now accepted that soil nitrous oxide (N2O) emissions occur under freezing conditions (Sommerfeld et al., 1993; Pelster et al., 2012), and that overwinter N2O emissions may represent a substantial portion of the total annual emissions from agricultural soils in northern countries (Maljanen et al., 2007; Wagner-Riddle et al., 2007; Virkajärvi et al., 2010). However, the temporal dynamics during winter are poorly documented, and the question whether manure application in the fall may increase winter N2O emissions is under debate. In addition, the possible influence of soil texture in regulating N2O emissions during winter has been overlooked. Our objective was to compare N2O emissions above the snow cover on sandy and clayey soils with and without pig slurry applied in the fall.

What did we do?

The study was carried out for three consecutive winter periods (2010-2013) on a sandy loam and a silty clay soil. Soil N2O concentration and emission were monitored weekly from November to May using soil probes and static chambers, respectively. The static chambers were made of 20-cm diameter white PVC pipe. The chamber base (15 cm height) was permanently inserted to 10 cm depth. Pig slurry was applied within half of the chamber bases (5 per soil type), whereas the other half remained unamended (Control treatment). The manure was immediately incorporated into the top 5 cm of soil using hand tools; soil in control chambers was similarly disturbed. Additional sections of PVC pipe (10 cm height) were secured on the top of each chamber base as the snowpack developed, and were removed stepwise in the spring during snowmelt. The chamber base was therefore emerging above the snow cover at time of chamber deployment. On each sampling date, the accumul ation of N2O within the chamber headspace was monitored at 6-min intervals during 18-min deployments. Soil air was also collected weekly through soil probes installed at 7.5 cm depth. Air samples were withdrawn with a syringe and transferred to pre-evacuated vials. Gas samples in vials were analyzed for N2O within 48 h using a gas chromatograph.

Title: Nitrous Oxide Emissions in Snow-covered Agricultural Soils – manure-induced fluxes

Authors and affiliations:

Martin H. Chantigny, Philippe Rochette & Denis A. Angers, Agriculture and Agri-Food Canada, Québec;

Claudia Goyer, Agriculture and Agri-Food Canada, Fredericton, Canada

Table 1. Range of cumulative N₂O-N emission, magnitude of emissions, and emission factors measured for three consecutive winter periods.
	Sandy loam	Silty clay
Cumulative emission (kg N₂O-N/ha)	0.1 to 2.0	0.6 to 1.6
Magnitude of emissions (% of total annual emission)	32 to 67	10 to 27
Emission factor (% N applied)	0.3 to 3.0	0.9 to 2.4

What have we learned?

Nitrous oxide was produced in soils and emitted in all years, with a low in late fall (Nov.-Dec.) and significant increases when snow depth exceeded 20 cm (late Dec. – early Jan.) and during spring thaw (late March – early April). Ice formation on and within the soil occurred during freeze-thaw events. This phenomenon generally blocked the emission of N2O but did not prevent its production in the soil. Therefore ice formation resulted in a marked decline in N2O emissions with concurrent increase in soil N2O concentration. The temporal dynamics of N2O emissions was variable among years, and the significance of manure-induced N2O emissions was mainly explained by early winter frost penetration, which was dependent on snow accumulation in late fall. As opposed to N2O emissions measured during the growing season, sandy soils tended to emit as much N2O as clayey soils during the non-growing season. Consequently, the cumulative N2O-N emi ssions in the non-growing season (November-April) accounted for 10 to 25% of total annual emissions in clayey soils, and from 20 to 70% in sandy soils (Table 1). Soils amended with pig slurry in the fall emitted more N2O than soils without, with emissions factors up to 3%, higher than the default IPCC coefficient (1%).

References

Pelster, D.E., Chantigny, M.H., Rochette, P., Angers, D.A., Laganière, J., Zebarth, B., Goyer, C. 2012. Crop residue incorporation alters soil nitrous oxide emissions during freeze-thaw cycles. Can. J. Soil Sci. 93:415-425.

Sommerfeld, R.A., Mosier, A.R., Musselman, R.C. 1993. CO2, CH4, and N2O flux through a Wyoming snowpack and implications for global budgets. Nature 361:140-142.

Virkajärvi P., Maljanen M., Saarijarvi K., Haapala J., Martikainen P.J. 2010. N2O emissions from boreal grass and grass-clover pasture soils. Agric. Ecosyst. Environ. 137, 59-67.

Wagner-Riddle, C., Furon, A., McLaughlin, N. L., Lee, I., Barbeau, J., Jayasundara, S., Parkin, G., von Bertoldi, B., Warland, J. 2007. Intensive measurement of nitrous oxide emissions from a corn-soybean-wheat rotation under two contrasting management systems over 5 years. Global Change Biol. 13:1722-1736.

Future Plans

Now that we evidenced the significance of N2O emissions from soils during the winter period, we are initiating field work to determine best practices for fall application of manure (e.g. early vs. late fall application; use of additives to delay nitrification of manure ammonia) that will mitigate losses and help efficiently transferring applied N to crop in the next spring.