,PHACE Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in Cheyenne, Wyoming,

,ACRE Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in West Lafayette, Indiana In-field measurements of direct soil greenhouse gas (GHG) emissions provide critical data for quantifying the net energy efficiency and economic feasibility of crop residue based bioenergy production systems. A major challenge to such assessments has been the paucity of field studies addressing the effects of crop residue removal and associated best practices for soil management (i.e., conservation tillage) on soil emissions of carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4). This regional survey summarizes soil GHG emissions from nine maize production systems evaluating different levels of corn stover removal under conventional or conservation tillage management across the US Corn Belt. Cumulative growing season soil emissions of CO2, N2O, and/ or CH4 were measured for 2–5 years (2008–2012) at these various sites using a standardized static vented chamber technique as part of the USDA-ARS’s Resilient Economic Agricultural Practices (REAP) regional partnership. Cumulative soil GHG emissions during the growing season varied widely across sites, by management, and by year. Overall, corn stover removal decreased soil total CO2 and N2O emissions by -4 and -7 %, respectively, relative to no removal. No management treatments affected soil CH4 fluxes.When aggregated to total GHG emissions (Mg CO2eq ha-1) across all sites and years, corn stover removal decreased growing season soil emissions by -5±1 % (mean±se) and ranged from -36 % to 54 % (n=50). Lower GHG emissions in stover removal treatments were attributed to decreased C and N inputs into soils, as well as possible microclimatic differences associated with changes in soil cover. High levels of spatial and temporal variabilities in direct GHG emissions highlighted the importance of site-specific management and environmental conditions on the dynamics of GHG emissions from agricultural soils.,

,CSR1 Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in Watkinsville, Georgia,

,TPAC Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in West Lafayette, Indiana Recent efforts have attempted to establish emission estimates for greenhouse gases (GHG) from agricultural soils in the United States. This research project was conducted to assess the influence of cropping system management on non-carbon dioxide (non-CO2) GHG emissions from an eastern cornbelt alfisol. Corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) rotation plots were established, as were plots in continuous management of native grasses or Sorghum/Sudan grass. GHG fluxes were monitored throughout each growing season from 2004 through 2007. Fluxes of N2O were significantly correlated with soil temperature (P < 0.001), and thus a Q10 correction was made (3.48 for N2O). Nitrous oxide emissions from corn were lowest from the precision tillage treatment (2.4 kg N ha-1 yr-1), significantly lower than the conventional tillage (4.9 kg N ha-1 yr-1) or cover crop corn treatments (5.0 kg N ha-1 yr-1). Corn-soybean and biomass-based cropping systems resulted in significantly greater N2O emissions than native grasses. There was a positive correlation between N fertilization rate and N2O emissions when comparing all treatments in this study. These soils were typically a sink for atmospheric CH4 for these cropping systems, and thus N2O is the primary non-CO2 GHG of concern. When evaluating the entire cropping system, native grasses resulted in the lowest N2O emissions, while corn-soybean rotation planted with precision tillage resulted in similar N2O emissions as bare soil and were significantly lower than emissions from the other cropping systems assessed.,

,WQFS Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in West Lafayette, Indiana Relative contributions of diverse, managed ecosystems to greenhouse gases are not completely documented. This study was conducted to estimate soil surface fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2 O) as affected by management practices and weather. Gas fluxes were measured by vented, static chambers in Drummer and Raub soil series during two growing seasons. Treatments evaluated were corn cropped continuously (CC) or in rotation with soybean (CS) and fertilized with in-season urea-ammonium nitrate (UAN) or liquid swine manure applied in the spring or fall. Soybean (SC) rotated with CS and restored prairie grass (RP) were also included. The CO2 fluxes correlated (P≤0.001) with soil temperature (ρ: 0.74) and accumulated rainfall 120 h before sampling (ρ: 0.53); N2O fluxes correlated with soil temperature (ρ: 0.34). Seasonal CO2–C emissions were not different across treatments (4.4 Mg ha−1 yr−1) but differed between years. Manured soils were net seasonal CH4–C emitters (0.159–0.329 kg ha−1 yr−1), whereas CSUAN and CCUAN Treatments significantly influenced seasonal N2O–N emissions (P< 0.001) and ranged from <1.0 kg ha−1yr−1in RP and SC to between 3 and 5 kg ha−1yr−1in CC (fall application) and CSUAN and >8 kg ha−1yr−1in CC (spring application); differences were driven by pulse emissions after N fertilization in concurrence with major rainfall events. These results suggest fall manure application, corn–soybean rotation, and restoration of prairies may diminish N2O emissions and hence contribute to global warming mitigation.,

,See the record in the GeoData catalog for additional materials and methods about this dataset, as well as links to data files: https://geodata.nal.usda.gov/geonetwork/srv/eng/catalog.search#/metadata/7685b3e7-5006-4c9c-a0ff-3562aa837985,

,CSR2 Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in Watkinsville, Georgia,

,ORPEGN Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in Pendleton, Oregon None,

,Global Warming Potential Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in Mandan, North Dakota No long-term evaluation of net global warming potential (GWP) for grassland ecosystems in the northern Great Plains (NGP) of North America has been reported. Given this need, we sought to determine net GWP for three grazing management systems located within the NGP. Grazing management systems included two native vegetation pastures (moderately grazed pasture [MGP], heavily grazed pasture [HGP]) and a heavily grazed crested wheatgrass [Agropyron desertorum (Fisch. ex. Link) Schult.] pasture (CWP) near Mandan, ND. Factors evaluated for their contribution to GWP included (i) CO2 emissions associated with N fertilizer production and application, (ii) literature-derived estimates of CH4 production for enteric fermentation, (iii) change in soil organic carbon (SOC) over 44 yr using archived soil samples, and (iv) soil–atmosphere N2O and CH4 fl uxes over 3 yr using static chamber methodology. Analysis of SOC indicated all pastures to be significant sinks for SOC, with sequestration rates ranging from 0.39 to 0.46 Mg C ha−1 yr−1. All pastures were minor sinks for CH4 (<2.0 kg CH4–C ha−1 yr−1). Greater N inputs within CWP contributed to annual N2O emission nearly threefold greater than HGP and MGP. Due to diff erences in stocking rate, CH4 production from enteric fermentation was nearly threefold less in MGP than CWP and HGP. When factors contributing to net GWP were summed, HGP and MGP were found to serve as net CO2equiv. sinks, while CWP was a net CO2equiv. source. Values for GWP and GHG intensity, however, indicated net reductions in GHG emissions can be most eff ectively achieved through moderate stocking rates on native vegetation in the NGP.,

,SMT Study for Greenhouse gas Reduction through Agricultural Carbon Enhancement network in St. Paul, Minnesota Carbon and Nitrogen Storage are Greater under Biennial Tillage in a Minnesota Corn-Soybean Rotation. Venterea, Rodney T., Baker, John M., Dolan, Michael S., Spokas, Kurt A., Soil Science Society of America Journal; Madison. http://search.proquest.com/assets/r20171.4.0.302.1590/core/spacer.gif70.5http://search.proquest.com/assets/r20171.4.0.302.1590/core/spacer.gif (Sep/Oct 2006): 1752-1762. Few studies have examined the impacts of rotational tillage regimes on soil carbon (C) and nitrogen (N). We measured the C and N content of soils managed under corn (Zea mays L.)-soybean (Glycine max L.) rotation following 10 and 15 yr of treatments. A conventional tillage (CT) regime employing moldboard and chisel plowing in alternate years was compared with both continuous no-till (NT) and biennial tillage (BT), which employed chisel plowing before soybean only. While masses of C and N in the upper 0.3 m under both BT and NT were higher than CT, only the BT treatment differed from CT when the entire sampled depth (0.6 m) was considered. Decreased C inputs, as indicated by reduced grain yields, may have limited C storage in the NT system. Thus, while more C was apparently retained under NT per unit of C input, some tillage appears necessary in this climate and cropping system to maximize C storage. Soil carbon dioxide (CO2) fluxes under NT were greater than CT during a drier than normal year, suggesting that C storage may also be partly constrained under NT due to wetter conditions that promote increased soil respiration. Increased temperature sensitivity of soil respiration with increasing soil moisture was also observed. These findings indicate that long-term biennial chisel plowing for corn-soybean in the upper mid-west USA can enhance C storage, reduce tillage-related fuel costs, and maintain yields compared with more intensive annual tillage. Urea Decreases Nitrous Oxide Emissions Compared with Anhydrous Ammonia in a Minnesota Corn Cropping System. Venterea, Rodney T; Dolan, Michael S; Ochsner, Tyson E. http://search.proquest.com/assets/r20171.4.0.302.1590/core/spacer.gif. Soil Science Society of AmericanJournal; Madison http://search.proquest.com/assets/r20171.4.0.302.1590/core/spacer.gif74.2http://search.proquest.com/assets/r20171.4.0.302.1590/core/spacer.gif (Mar/Apr 2010): 407-418. Quantifying N2O emissions from corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] fields under different fertilizer regimes is essential to developing national inventories of greenhouse gas emissions. The objective of this study was to compare N2O emissions in plots managed for more than 15 yr under continuous corn (C/C) vs. a corn-soybean (C/S) rotation that were fertilized during the corn phase with either anhydrous NH 3 (AA) or urea (U). During three growing seasons, N2O emissions from corn following corn were nearly identical to corn following soybean. In both systems, however, N2O emissions with AA were twice the emissions with U. After accounting for N2O emissions during the soybean phase, it was estimated that a shift from C/S to C/C would result in an increase in annual emissions of 0.78 kg N ha-1 (equivalent to 0.11 Mg CO2-C ha-1) when AA was used, compared with only 0.21 kg N ha-1 (0.03 Mg CO2-C ha-1) with U. In light of trends toward increased use of U, these results suggest that fertilizer-induced soil N2O emissions may decline in the future, at least per unit of applied N, although further study is needed in different soils and cropping systems. While soil CO2 emissions were 20% higher under C/C, crop residue from the prior year did not affect soil inorganic N or dissolved organic C during the subsequent season. We also compared different flux-calculation schemes, including a new method for correcting chamber-induced errors, and found that selection of a calculation method altered N2O emissions estimates by as much as 35%.,