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United States Department of Agriculture

Agricultural Research Service

Title: Soil Response to Long-Term Grazing in the Northern Great Plains of North America

Authors
item Liebig, Mark
item Gross, Jason
item Kronberg, Scott
item Hanson, Jonathan
item Frank, Albert - RETIRED, USDA-ARS
item Phillips, Beckie

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 29, 2005
Publication Date: April 19, 2006
Citation: Liebig, M.A., Gross, J.R., Kronberg, S.L., Hanson, J.D., Frank, A.B., Phillips, R.L. 2006. Soil response to long-term grazing in the northern Great Plains of North America. Agric. Ecosys. Environ. 115:270-276.

Interpretive Summary: In order to better understand grazing influences on soil condition and ecosystem function, an evaluation was conducted near Mandan, North Dakota on the long-term (over 70 yr) effects of grazing management on soil properties and nitrous oxide emission. Three grazing management systems - a moderately-grazed native vegetation pasture (MGP), heavily-grazed native vegetation pasture (HGP), and a fertilized crested wheatgrass pasture (FCWP) – were evaluated in October 2003. Grazing-induced changes in species composition and N fertilizer application contributed to differences in soil properties and nitrous oxide emission among pastures. Soil organic carbon tended to be greater in FCWP and HGP than MGP at surface soil depths, while FCWP had greater soil organic carbon than HGP and MGP at a depth of 12 to 24 inches. Particulate organic matter - a labile fraction of soil organic matter – was approximately four-fold greater in FCWP than in HGP and MGP at the 0 to 2 inch depth. Acidification from N fertilization in FCWP decreased soil pH and cation exchange capacity compared to HGP and MGP in the surface two inches of soil. Annual nitrous oxide emission was over three-fold greater in FCWP compared to HGP and MGP, and was positively associated with particulate organic matter. Results from this study suggest fertilized crested wheatgrass enhances deep storage of soil organic carbon, but contributes to surface acidification and greater nitrous oxide emission relative to native nonfertilized pastures in the northern Great Plains.

Technical Abstract: Grazing management affects ecosystem function through impacts on soil condition. We investigated the effects of long-term (over 70 yr) grazing on soil properties and nitrous oxide emission within a moderately-grazed native vegetation pasture (MGP), heavily-grazed native vegetation pasture (HGP), and a fertilized crested wheatgrass (Agropyron desertorum (Fisch. ex. Link) Schult.) pasture (FCWP) near Mandan, North Dakota, USA. Grazing-induced changes in species composition and N fertilizer application contributed to differences in soil properties and N2O emission among pastures. Soil organic C (SOC) was 5.7 Mg/ha greater in FCWP and HGP than MGP at 0 to 5 cm, whereas HGP had 2.4 Mg/ha more SOC than FCWP and MGP at 5 to 10 cm. At 30 to 60 cm, SOC in FCWP was 4.0 and 7.5 Mg/ha greater than in HGP and MGP, respectively. Particulate organic matter (POM) C and N in the surface 5 cm of FCWP were three- and five-fold greater, respectively, than in HGP and MGP. Acidification from N fertilization in FCWP decreased soil pH and cation exchange capacity compared to HGP and MGP in the surface 5 cm. Annual nitrous oxide emission was over three-fold greater in FCWP compared to HGP and MGP, and was positively associated with POM-C across all pastures (P=0.0001; coefficient of determination=0.85). Results from this study suggest fertilized crested wheatgrass enhances deep storage of SOC, but contributes to surface acidification and greater nitrous oxide emission relative to native nonfertilized pastures in the northern Great Plains. [GRACEnet Publication]

Last Modified: 10/21/2014
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