Iwaasa, A. D.

McConkey, B.

Schellenberg, Michael P.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Effect of Grazing and Re‐Establishment of Native Species on Soil Organic Matter Sequestration for the Semiarid Central Grasslands of Canada A. D. Iwaasa Agriculture and Agri‐Food Canada, Canada B. McConkey Agriculture and Agri-Food Canada, Canada Michael P. Schellenberg Agriculture and Agri-Food Canada, Canada Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/8-1/17 The 21st International Grassland Congress / 8th International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅰ 　 瞯 ]885　 瞯Grasslands/Rangelands Resources and Ecology ——— Climate Change and Impact on Grasslands/RangelandsEffect of grazing and re‐establishment of native species on soil organic matter sequestration forthe semiarid central grasslands of CanadaIw aasa , A .D . , McConkey , B . and Schellenberg , M .A griculture and A gri‐Food Canada‐Semiarid Prairie A gricultural Research Centre (A A FC‐SPARC) ,Box 1030 , Sw i f t Current , Saskatchew an , Canada , S9H 3X2 , E‐mail : Iw aasa＠ agr .gc .caKey words :Carbon sequestration , beef cattle , native species , grazing , biodiversityIntroduction The native mixed grass prairie in North America is estimated to have been reduced to ２０ to ３０％ of its formerextent , due to agriculture expansion and urbanization . Aside from the importance that native grasslands play as a repository forbiodiversity , wildlife habitat and a grazing resource , the restoration and maintenance of native grasslands can provide animportant opportunity to mitigate greenhouse gas concerns through soil organic carbon ( SOC ) sequestration . Native grasseshave more extensive rooting system than tame species , and higher specie richness can result in higher SOC potential (Wedin andTilman １９９６) . Objective of this research was to evaluate the impact that grazing and non‐grazing treatments and different nativemixtures have on SOC sequestration potential in newly established native pastures .Materials and methods Sixteen pastures ( ２ ha ea) were randomly set up in a ２ × ２ factorial design with four replicates : twonative mixtures [７ species simple ( S) or １４ species complex ( C ) ] and two grazing utilization levels [ low ( ４０‐５０％ ) and high(６０‐７０％ ) ] . Seeding occurred in the spring of ２００１ using a double disk air seeder . Seeding rate for the S and C mixes were ９ .５ kg ha‐１ ［２５ pure live seeds ( PLS) per ０畅３０ m２ ] and ９ kg ha‐１ （３３ PLS per ０ .３０ m２ ) , respectively . Cattle grazing were fromthe end of June to September and in ２００２ , ２００３ and ２００４ . In each pasture a permanent enclosure (３ .６ × ３ .６ m) was used asthe non‐grazing treatment . In all pastures , SOC samples were taken in the fall of ２０００ and ２００４ . Prior to soil sampling allsurface residues in the area were cut and the soil surface flattened . In ２０００ , soil samples were taken from five different locationsites , while in ２００４ only three different location sites were used . At each location site , core samples were taken at six micro‐sites and at ０‐１５ , １５‐３０ , ３０‐４５ and ４５‐６０ cm . Determination of soil bulk density and sieving the soil sample through a ２‐mmwire sieve were done . Representative sub‐samples were ground and analyzed for SOC ( McConkey et al . ２００３ ) . Data wasanalyzed using the MIXED procedure from SAS Institute , Inc . (２０００) .Results and discussion Average annual C sequestration rate on the newly established native pasture was ５３０ kg ha‐１ yr‐１ . Insupport , a study by Mensah et al . (２００３) on dark Brown and Black soils in Saskatchewan compared favourably to our results .Favourable moisture conditions and forage productivity generally occurred for our study , which contributed to the excellent Csequestration potential . A seed mixture x pasture utilization ( P ＜ ０ .０５ ) interaction was observed and orthogonal contrastswere used . The simple ＋ high ( S ＋ H) treatment gave the highest ( P ＜ ０ .０５) SOC level compared to complex ＋ low (C ＋ L) ,S ＋ L and C ＋ H and the SOC changes were ３畅５９ , ２ .０３ , １ .４７ and ０ .９４ ± ０ .６８ Mg C ha‐１ , respectively . Higher SOCassociated with the S ＋ H may be due to more livestock hoof action breaking down and incorporating the standing dead and litterinto the soil and enhancing decomposition and reducing loss through oxidation ( Schuman et al . １９９９) . Highest pasture forageproduction was observed for the S native mix , thus higher SOC levels were not unexpected .Conclusion Excellent C sequestration rates can be achieved on newly established native pastures on brown soil land previouslyannually cropped . Pasture forage production and animal stocking rates can affect C sequestration levels .ReferencesMcConkey , B .G . , et al . ２００３ . Crop rotation and tillage impact on carbon sequestration in Canadian prairie soils . Soil &Tillage Research ７４ :８１‐９０ .Mensah , F . , Schoenau , J .J . and Malhi , S .S . ２００３ . Soil carbon changes in cultivated and excavated land converted to grassesin east‐central Saskatchewan . Biogeochemistry ６３ :８５‐９２ .Schuman , G .E . , et al . １９９９ . Impact of grazing management on the carbon and nitrogen balance of a mixed‐grass rangeland .Ecological A p p lications ９ :６５‐７１ .Wedin , D .A . and Tilman , D .１９９６ . Influence of nitrogen loading and species composition on the carbon balance of grasslands .Science ２７４ :１７２０‐１７２３ .

Effect of Grazing and Re‐Establishment of Native Species on Soil Organic Matter Sequestration for the Semiarid Central Grasslands of Canada

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Effect of Grazing and Re‐Establishment of Native Species on Soil Organic Matter Sequestration for the Semiarid Central Grasslands of Canada

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