Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2005
Publication Date: 3/21/2005
Citation: Liebig, M.A., Kronberg, S.L., Gross, J.R., Hanson, J.D., Frank, A.B., Phillips, R.L. 2005. Soil response to long-term grazing in the northern great plains. p. 156. IN: Proc. of the Third USDA Symposium on Greenhouse Gases and Carbon Sequestration in Agriculture and Forestry. 22-24 March 2005, Baltimore, MD. Interpretive Summary:
Technical Abstract: Grazing management systems affect agroecosystem sustainability 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 pasture (MGP), heavily-grazed pasture (HGP), and a fertilized crested wheatgrass (Agropyron desertorum (Fisch. ex. Link) Schult.) pasture (FCWGP) near Mandan, ND. Grazing-induced changes in species composition and N fertilizer application contributed to differences in soil properties and nitrous oxide emission among pastures. Soil organic C (SOC) was 5.7 Mg/ha greater in FCWGP and HGP than MGP at 0 to 5 cm, whereas HGP had 2.4 Mg/ha more SOC than FCWGP and MGP at 5 to 10 cm. At 30 to 60 cm, SOC in FCWGP 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 FCWGP were three- and five-fold greater, respectively, than in HGP and MGP. Acidification from N fertilization in FCWGP decreased soil pH and exchangeable Ca and Mg compared to HGP and MGP in the surface 5 cm. Annual nitrous oxide emission was over three-fold greater in FCWGP compared to HGP and MGP, and was positively associated with POM-C across all pastures (r=0.92; P<0.0001). 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 vegetation pastures in the northern Great Plains.