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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #288436
Title: Net global warming potential and greenhouse gas intensity affected by cropping sequence and nitrogen fertilization

Author
item Sainju, Upendra
item Barsotti, Joy
item WANG, JUN - Northwest Agricultural University

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2013
Publication Date: 1/31/2014
Citation: Sainju, U.M., Barsotti, J.L., Wang, J. 2014. Net global warming potential and greenhouse gas intensity affected by cropping sequence and nitrogen fertilization. Soil Science Society of America Journal. 78(1):248-261.

Interpretive Summary: Little is known about the effects of management practices on net global warming potential (GWP) and greenhouse gas intensity (GHGI) in dryland cropping systems. Since agricultural management practices produce three greenhouse gases (carbon dioxide [CO2], nitrous oxide [N2O], and methane [CH4]), it is the balance between soil organic C storage and N2O and CH4 emissions that typically control net GWP and GHGI .For understanding the agriculture’s impact on radiative forcing, all sources and sinks of CO2, N2O, and CH4 in the agroecosystem should be considered. We evaluated the effects of cropping sequences {conventional-tilled malt barley -fallow [CTB-F], no-tilled malt barley-pea rotation [NTB-P], and no-tilled continuous malt barley [NTCB]} and N fertilization rates (0 and 80 kg N ha-1) on dryland soil greenhouse gas (GHG) emissions, GWP, and GHGI from 2008 to 2011 in eastern Montana, USA. The CO2 and N2O fluxes and CH4 uptake from spring to autumn were greater in NTB-P and NTCB with 80 kg N ha-1 than in other treatments. Net GWP and GHGI based on soil respiration and GHGI based on soil organic C (SOC) were greater in NTCB with 0 kg N ha-1 but GWP based on SOC was greater in CTB-F with 0 kg N ha-1 than in NTB-P with 0 and 80 kg N ha-1. Because of increased grain yield but reduced GWP and GHGI, NTB-P with 80 kg N ha-1 may be used as a management option to reduce dryland GWP and GHGI while sustaining crop yields in the northern Great Plains, USA.

Technical Abstract: Little information is available about management practice effects on the net global warming potential (GWP) and greenhouse gas intensity (GHGI) under dryland cropping systems. We evaluated the effects of cropping sequences (conventional-tillage malt barley [Hordeum vulgaris L.]–fallow [CTB-F], no-till malt barley–pea [Pisum sativum L.] [NTB-P], and no-till continuous malt barley [NTCB]) and N fertilization rates (0 and 80 kg N ha-1) on net GWP and GHGI from 2008 to 2011 in eastern Montana. Carbon dioxide sources from farm operations were greater under CTB-F than NTB-P and NTCB and greater with N fertilization than without, but the sources from soil greenhouse gases (GHGs) varied among treatments and years. Carbon dioxide sinks from crop residue and soil organic C (SOC) sequestration were greater under NTB-P or NTCB with 80 kg N ha-1 than other treatments. Net GWP and GHGI based on soil respiration (GWPR and GHGIR, respectively) and SOC (GWPC and GHGIC, respectively) were greater under CTB-F with 0 kg N ha-1 than other treatments, suggesting that alternate-year fallow and the absence of N fertilization to crops can increase net GHG emissions. Because of greater grain yield but lower GWP and GHGI, NTB-P with N rates between 0 and 80 kg N ha-1 may be used as management options to mitigate global warming potential while sustaining dryland malt barley and pea yields compared with CTB-F with 0 kg N ha-1 in the northern Great Plains. The results can be applied to other semiarid regions with similar soil and climatic conditions.