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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on C(N2O)2 by Materials Project

C(N2O)2 crystallizes in the orthorhombic Fdd2 space group. The structure is zero-dimensional and consists of sixteen 2-nitroguanidine molecules. C4+ is bonded in a trigonal planar geometry to three N atoms. There are a spread of C–N bond distances ranging from 1.34–1.40 Å. There are four inequivalent N sites. In the first N site, N is bonded in a distorted single-bond geometry to one C4+ atom. In the second N site, N is bonded in a single-bond geometry to one C4+ atom. In the third N site, N is bonded in a distorted bent 120 degrees geometry to one C4+ and one N atom. The N–N bond length is 1.41 Å. In the fourth N site, N is bonded in a distorted trigonal planar geometry to one N and two O2- atoms. There is one shorter (1.23 Å) and one longer (1.24 Å) N–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one N atom. In the second O2- site, O2- is bonded in a single-bond geometry to one N atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on C(N2O)2 by Materials Project

CN2N2O2 crystallizes in the orthorhombic Fdd2 space group. The structure is one-dimensional and consists of sixteen methanediamine molecules; sixteen N2 ribbons oriented in the (1, 0, 0) direction; and twenty-four O2 ribbons oriented in the (1, 0, 0) direction. In each N2 ribbon, there are two inequivalent N sites. In the first N site, N is bonded in a T-shaped geometry to three N atoms. There is one shorter (1.29 Å) and two longer (1.65 Å) N–N bond length. In the second N site, N is bonded in a distorted T-shaped geometry to three N atoms. Both N–N bond lengths are 1.65 Å. In eight of the O2 ribbons, O2- is bonded in a distorted T-shaped geometry to three equivalent O2- atoms. There is two shorter (1.65 Å) and one longer (2.25 Å) O–O bond length. In sixteen of the O2 ribbons, O2- is bonded in a distorted linear geometry to two equivalent O2- atoms. Both O–O bond lengths are 1.65 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AuC4(N2O)2 by Materials Project

AuC4(N2O)2 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one AuC4(N2O)2 sheet oriented in the (1, 0, 2) direction. Au2+ is bonded in a square co-planar geometry to four C+3.50+ atoms. All Au–C bond lengths are 2.01 Å. There are two inequivalent C+3.50+ sites. In the first C+3.50+ site, C+3.50+ is bonded in a single-bond geometry to one Au2+ and one N3- atom. The C–N bond length is 1.17 Å. In the second C+3.50+ site, C+3.50+ is bonded in a single-bond geometry to one Au2+ and one N3- atom. The C–N bond length is 1.16 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted single-bond geometry to one C+3.50+ and one O2- atom. The N–O bond length is 2.24 Å. In the second N3- site, N3- is bonded in a distorted linear geometry to one C+3.50+ and one O2- atom. The N–O bond length is 2.20 Å. O2- is bonded in a 2-coordinate geometry to two N3- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Climate-carbon feedback tradeoff between Arctic and alpine permafrost under warming

Whether greenhouse gas (GHG) emissions from permafrost will trigger positive climate feedbacks under warming remains unknown. Here, we synthesized the response of growing season carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions to experimentally manipulated warming of ~2°C for permafrost in alpine and Arctic regions. Warming weakened the GHG sink of alpine permafrost, thereby increasing (13%) its global warming potential, but strengthened the GHG sink of Arctic permafrost and decreased (-10%) its global warming potential. When warming caused drying of alpine permafrost soils, the CO2 sink weakened but the CH4 sink increased. In contrast, warming of relatively wet Arctic permafrost increased the CO2 sink and CH4 source. Warming led to much stronger increases of the N2O source in alpine than Arctic permafrost. Although keeping additional warming below 2°C in permafrost regions can avoid the positive permafrost-climate feedback, measures are needed to maintain fragile carbon sink of alpine permafrost ecosystems.

Bao, Tao↗
DOE OSTI2020

Materials Data on BH5C4(N2O)2 by Materials Project

(B)6(CN)4(H5(C2N)2)2(CNH2)4(CHNO2)4(N2H)4(H(CO)2)2H2 crystallizes in the orthorhombic Pnn2 space group. The structure is zero-dimensional and consists of six boron molecules; four carbamic acid molecules; four diazene molecules; two formalin formaldehyde molecules; two hydrogen molecules; four hydrogen cyanide molecules; four methylamine molecules; and two n,n'-dimethylethylenediamine molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H4C(N2O)2 by Materials Project

CH4(N2O)2 crystallizes in the orthorhombic Fdd2 space group. The structure is one-dimensional and consists of four CH4(N2O)2 ribbons oriented in the (-1, 0, 1) direction. C4+ is bonded in a trigonal planar geometry to three N1- atoms. There are a spread of C–N bond distances ranging from 1.33–1.40 Å. There are four inequivalent N1- sites. In the first N1- site, N1- is bonded in a distorted bent 120 degrees geometry to one C4+ and one N1- atom. The N–N bond length is 1.28 Å. In the second N1- site, N1- is bonded in a distorted bent 120 degrees geometry to one N1- and one O2- atom. The N–O bond length is 1.36 Å. In the third N1- site, N1- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the fourth N1- site, N1- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.01 Å) and one longer (1.06 Å) N–H bond length. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the fourth H1+ site, H1+ is bonded in a distorted linear geometry to one N1- and one O2- atom. The H–O bond length is 1.65 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one N1- and one O2- atom. The O–O bond length is 1.39 Å. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one H1+ and one O2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HAuC4(N2O)2 by Materials Project

AuC4H(N2O)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Au1- is bonded in a square co-planar geometry to four C4+ atoms. All Au–C bond lengths are 2.01 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a distorted single-bond geometry to one Au1- and one N3- atom. The C–N bond length is 1.17 Å. In the second C4+ site, C4+ is bonded in a distorted single-bond geometry to one Au1- and one N3- atom. The C–N bond length is 1.16 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a distorted single-bond geometry to one C4+ and one O2- atom. The N–O bond length is 2.19 Å. In the second N3- site, N3- is bonded in a distorted linear geometry to one C4+ and one O2- atom. The N–O bond length is 2.25 Å. H1+ is bonded in a linear geometry to two equivalent O2- atoms. Both H–O bond lengths are 1.24 Å. O2- is bonded in a single-bond geometry to two N3- and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H4C(N2O)2 by Materials Project

CH4(N2O)2 crystallizes in the orthorhombic Fdd2 space group. The structure is zero-dimensional and consists of sixteen 2-nitroguanidine molecules. C4+ is bonded in a trigonal planar geometry to three N1- atoms. There is two shorter (1.33 Å) and one longer (1.37 Å) C–N bond length. There are four inequivalent N1- sites. In the first N1- site, N1- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the second N1- site, N1- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the third N1- site, N1- is bonded in a distorted bent 120 degrees geometry to one C4+ and one N1- atom. The N–N bond length is 1.34 Å. In the fourth N1- site, N1- is bonded in a distorted trigonal planar geometry to one N1- and two O2- atoms. There is one shorter (1.26 Å) and one longer (1.27 Å) N–O bond length. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N1- atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one N1- atom. In the second O2- site, O2- is bonded in a single-bond geometry to one N1- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SiH18C4N8(O2F3)2 by Materials Project

(C2H9(N2O)2)2SiF6 crystallizes in the tetragonal P4_12_12 space group. The structure is zero-dimensional and consists of eight C2H9(N2O)2 clusters and four SiF6 clusters. In four of the C2H9(N2O)2 clusters, C4+ is bonded in a trigonal planar geometry to two N3- and one O2- atom. Both C–N bond lengths are 1.34 Å. The C–O bond length is 1.30 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the second N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two equivalent H1+ atoms. Both N–H bond lengths are 1.01 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two equivalent O2- atoms. Both H–O bond lengths are 1.20 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. O2- is bonded in a bent 120 degrees geometry to one C4+ and one H1+ atom. In four of the C2H9(N2O)2 clusters, C4+ is bonded in a trigonal planar geometry to two N3- and one O2- atom. Both C–N bond lengths are 1.34 Å. The C–O bond length is 1.29 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the second N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. There are five inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a linear geometry to two equivalent O2- atoms. Both H–O bond lengths are 1.21 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. O2- is bonded in a bent 120 degrees geometry to one C4+ and one H1+ atom. In each SiF6 cluster, Si4+ is bonded in an octahedral geometry to six F1- atoms. There are a spread of Si–F bond distances ranging from 1.72–1.74 Å. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Si4+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Si4+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2H4PtC4Br2(N2O)2 by Materials Project

Na2PtC4H4Br2(N2O)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Na1+ is bonded to four N3- and two equivalent O2- atoms to form distorted face-sharing NaN4O2 octahedra. There are a spread of Na–N bond distances ranging from 2.52–2.72 Å. There are one shorter (2.42 Å) and one longer (2.44 Å) Na–O bond lengths. Pt2- is bonded in an octahedral geometry to four C+3.50+ and two Br1- atoms. All Pt–C bond lengths are 2.02 Å. There are one shorter (2.52 Å) and one longer (2.53 Å) Pt–Br bond lengths. There are two inequivalent C+3.50+ sites. In the first C+3.50+ site, C+3.50+ is bonded in a linear geometry to one Pt2- and one N3- atom. The C–N bond length is 1.17 Å. In the second C+3.50+ site, C+3.50+ is bonded in a linear geometry to one Pt2- and one N3- atom. The C–N bond length is 1.17 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a 1-coordinate geometry to two equivalent Na1+ and one C+3.50+ atom. In the second N3- site, N3- is bonded in a 1-coordinate geometry to two equivalent Na1+ and one C+3.50+ atom. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. O2- is bonded in a distorted water-like geometry to two equivalent Na1+ and two H1+ atoms. There are two inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a single-bond geometry to one Pt2- atom. In the second Br1- site, Br1- is bonded in a single-bond geometry to one Pt2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K3ReC4(N2O)2 by Materials Project

K3ReC4(N2O)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in an octahedral geometry to four N3- and two equivalent O2- atoms. There are two shorter (2.88 Å) and two longer (2.93 Å) K–N bond lengths. Both K–O bond lengths are 2.91 Å. In the second K1+ site, K1+ is bonded in a 4-coordinate geometry to two N3- and two equivalent O2- atoms. There are one shorter (2.83 Å) and one longer (2.85 Å) K–N bond lengths. There are one shorter (2.85 Å) and one longer (2.90 Å) K–O bond lengths. Re5+ is bonded in a linear geometry to two equivalent O2- atoms. Both Re–O bond lengths are 1.81 Å. There are two inequivalent C2+ sites. In the first C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.18 Å. In the second C2+ site, C2+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.18 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a 1-coordinate geometry to two K1+ and one C2+ atom. In the second N3- site, N3- is bonded in a 1-coordinate geometry to two K1+ and one C2+ atom. O2- is bonded in a distorted single-bond geometry to three K1+ and one Re5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZnH8C2I2(N2O)2 by Materials Project

ZnC2H8I(N2O)2I crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of four hydriodic acid molecules and two ZnC2H8I(N2O)2 ribbons oriented in the (0, 1, 0) direction. In each ZnC2H8I(N2O)2 ribbon, Zn2+ is bonded to one N3-, one O2-, and two equivalent I1- atoms to form distorted corner-sharing ZnI2NO tetrahedra. The Zn–N bond length is 2.14 Å. The Zn–O bond length is 1.94 Å. There are one shorter (2.69 Å) and one longer (2.72 Å) Zn–I bond lengths. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to two N3- and one O2- atom. There is one shorter (1.34 Å) and one longer (1.45 Å) C–N bond length. The C–O bond length is 1.23 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to two N3- and one O2- atom. Both C–N bond lengths are 1.34 Å. The C–O bond length is 1.29 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the second N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.03 Å. In the third N3- site, N3- is bonded in a 4-coordinate geometry to one Zn2+, one C4+, and two H1+ atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the fourth N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. There is one shorter (1.01 Å) and one longer (1.03 Å) N–H bond length. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C4+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Zn2+ and one C4+ atom. I1- is bonded in a bent 120 degrees geometry to two equivalent Zn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZnC2(N2O)4 by Materials Project

Zn(N2)4(CO2)2 is Cyanogen Chloride-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four carbon dioxide molecules, eight nitrogen molecules, and two zinc molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Chemical identity of carbon substrates drives differences in denitrification and N 2 O reduction within agricultural soils

Rates of nitrous oxide (N 2 O) production from agricultural soils are highly variable across space and time. Improving predictions of N 2 O emissions will require improving our understanding of the drivers of denitrification and the sources of variability in the rates of N 2 O production between soils and over time. While the amount of available carbon (C) is a known control on denitrification and N 2 O reduction, relatively little attention has been paid to the effect of the chemical identity of C substrates on rates of denitrification and N 2 O reduction. We investigated the effects of twelve different C-substrate additions on the production and reduction of N 2 O in five soils taken from two distinct agricultural locations in Michigan under multiple land uses. We provided additions of glucose, cellulose, N-acetyl-glucosamine, chitin, amino acids, protein, vanillyl alcohol, lignin, citrate, succinate, methanol, and water in laboratory denitrification potential assays to determine the effects of denitrifier C preference on denitrification rates. We found that amino acids, protein, and organic acids stimulated the greatest rates of denitrification potential across all land uses. Similarly, we found these same substrates caused the most N 2 O reduction, resulting in the lowest net concentrations of N 2 O. Soils from agricultural rotations without cover crops had overall lower rates of denitrifier activity, leading to less net N 2 O production compared to soils from other land uses. In general, C-utilization patterns were similar among all soils, and C-substrate identity had a much stronger effect than land use. Here, we demonstrate that the chemical identity of available C gives rise to wide variability in rates of denitrification and N 2 O reduction.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Materials Data on GdAu3C6(N2O)3 by Materials Project

GdAu3C6(N2O)3 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. Gd3+ is bonded in a 9-coordinate geometry to six equivalent N3- and three equivalent O2- atoms. All Gd–N bond lengths are 2.48 Å. All Gd–O bond lengths are 2.42 Å. Au1- is bonded in a linear geometry to two equivalent C4+ atoms. Both Au–C bond lengths are 2.00 Å. C4+ is bonded in a distorted single-bond geometry to one Au1- and one N3- atom. The C–N bond length is 1.17 Å. N3- is bonded in a 2-coordinate geometry to one Gd3+ and one C4+ atom. O2- is bonded in a distorted single-bond geometry to one Gd3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnH58C16S4(N11O9)2 by Materials Project

SnC6H22(N2O)4(CO(NH2)2)6(C2NH6S2O4)2 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two dimethanesulfonamide molecules, six urea molecules, and one SnC6H22(N2O)4 cluster. In the SnC6H22(N2O)4 cluster, Sn is bonded in an octahedral geometry to two equivalent C and four O atoms. Both Sn–C bond lengths are 2.13 Å. There are two shorter (2.27 Å) and two longer (2.30 Å) Sn–O bond lengths. There are three inequivalent C sites. In the first C site, C is bonded in a trigonal planar geometry to two N and one O atom. Both C–N bond lengths are 1.35 Å. The C–O bond length is 1.29 Å. In the second C site, C is bonded in a distorted trigonal non-coplanar geometry to one Sn and three H atoms. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. In the third C site, C is bonded in a trigonal planar geometry to two N and one O atom. There is one shorter (1.34 Å) and one longer (1.35 Å) C–N bond length. The C–O bond length is 1.29 Å. There are four inequivalent N sites. In the first N site, N is bonded in a trigonal planar geometry to one C and two H atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the second N site, N is bonded in a trigonal planar geometry to one C and two H atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the third N site, N is bonded in a trigonal planar geometry to one C and two H atoms. There is one shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the fourth N site, N is bonded in a trigonal planar geometry to one C and two H atoms. Both N–H bond lengths are 1.02 Å. There are ten inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one C atom. In the second H site, H is bonded in a single-bond geometry to one N atom. In the third H site, H is bonded in a single-bond geometry to one N atom. In the fourth H site, H is bonded in a single-bond geometry to one N atom. In the fifth H site, H is bonded in a single-bond geometry to one N atom. In the sixth H site, H is bonded in a single-bond geometry to one N atom. In the seventh H site, H is bonded in a single-bond geometry to one N atom. In the eighth H site, H is bonded in a single-bond geometry to one N atom. In the ninth H site, H is bonded in a single-bond geometry to one N atom. In the tenth H site, H is bonded in a single-bond geometry to one C atom. There are two inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to one Sn and one C atom. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one Sn and one C atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Data from: No‐till establishment improves the climate benefit of bioenergy crops on marginal grasslands

Expanding biofuel production is expected to accelerate the conversion of unmanaged marginal lands to meet biomass feedstock needs. Greenhouse gas production during conversion jeopardizes ensuing climate benefits, but most research to date has focused only on conversion to annual crops and only following tillage. Here we report the global warming impact of converting USDA Conservation Reserve Program (CRP) grasslands to three types of bioenergy crops using no-till (NT) versus conventional tillage (CT). In three CRP fields planted to continuous corn, switchgrass, or restored prairie we established replicated NT and CT plots. For the two years following an initial soybean year in all fields, we found that, on average, NT conversion reduced nitrous oxide (N2O) emissions by 50% and carbon dioxide (CO2) emissions by 20% compared to CT conversion. Differences were higher in year 1 than in year 2 in the continuous corn field, and in the two perennial systems the differences disappeared after year 1. In all fields net CO2 emissions (as measured by eddy covariance) were positive for the first two years following CT establishment, but following NT establishment net CO2 emissions were close to zero or negative, indicating net C sequestration. Overall, NT improved the global warming impact of biofuel crop establishment following CRP conversion by over 20-fold compared to CT (-6.01 Mg CO2e ha-1 yr-1 for NT vs. -0.25 Mg CO2e ha-1 yr-1 for CT, on average). We also found that IPCC estimates of N2O emissions (as measured by static chambers) greatly underestimated actual emissions for converted fields regardless of tillage. Policies should encourage adoption of NT for converting marginal grasslands to perennial bioenergy crops in order to reduce carbon debt and maximize climate benefits.

09 BIOMASS FUELS↗