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Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/7/2014 Publication Date: 5/14/2014 Publication URL: http://handle.nal.usda.gov/10113/58776 Citation: Sainju, U.M. 2014. Cropping sequence and nitrogen fertilization impact on surface residue, soil carbon sequestration, and crop yields. Agronomy Journal. 106(4):1231-1242. Interpretive Summary: In the northern Great Plains, USA, traditional dryland farming systems, such as conventional tillage with crop-fallow, have resulted in soil carbon storage decline by 30 to 50% of their original levels in the last 50 to 100 yr. As a result, the traditional farming system has become inefficient, uneconomical, and unsustainable. Information on the long-term effect of management practices on residue and soil C storage for obtaining farm C credit and its relationship with crop yields under semiarid dryland cropping systems is lacking in the northern Great Plains, USA. The effects of tillage, cropping sequence, and N fertilization were evaluated on dryland crop and surface residue C and soil organic C (SOC) at the 0-120 cm depth in a Williams loam from 2006 to 2011 in eastern Montana, USA. Treatments were no-till continuous malt barley (NTCB), no-till malt barley-pea (NTB-P), no-till malt barley-fallow (NTB-F), and conventional till malt barley-fallow (CTB-F) (traditional system), each with 0, 40, 80, and 120 kg N ha-1. Annualized grain and biomass (stems + leaves) yields, surface residue amount, and C contents were greater in NTB-P and NTCB than in CTB-F and NTB-F in all years, except in 2006 and 2008, and increased with increased N rates. The SOC at 0-5 and 5-10 cm was greater with 40 than with 0 kg N ha-1 in NTB-P, but at 30-60 cm was greater with 120 than with 0 kg N ha-1 in CTB-F, NTB-F, and NTB-P. Tillage had no effect on crop yield and SOC. Surface residue C and SOC related with grain yield and C content (R2 =0.21-0.55, P = 0.10). Greater amount of crop residue returned to the soil probably increased crop yields and surface residue and soil C storage at surface layers in NTB-P with 40 kg N ha-1. This management practice may also reduce the potentials for soil erosion, N leaching, and pest incidences compared to the traditional system. Technical Abstract: Information is needed on the effect of management practices on soil C storage for obtaining C credit. The effects of tillage, cropping sequence, and N fertilization were evaluated on dryland crop and surface residue C and soil organic C (SOC) at the 0-120 cm depth in a Williams loam from 2006 to 2011 in eastern Montana, USA. Treatments were no-till continuous malt barley (Hordeum vulgaris L.) (NTCB), no-till malt barley-pea (Pisum sativum L.) (NTB-P), no-till malt barley-fallow (NTB-F), and conventional till malt barley-fallow (CTB-F) (traditional system), each with 0, 40, 80, and 120 kg N ha-1. Annualized grain and biomass (stems + leaves) yields, surface residue amount, and C contents were greater in NTB-P and NTCB than in CTB-F and NTB-F in all years, except in 2006 and 2008, and increased with increased N rates. The SOC at 0-5 and 5-10 cm was greater with 40 than with 0 kg N ha-1 in NTB-P, but at 30-60 cm was greater with 120 than with 0 kg N ha-1 in CTB-F, NTB-F, and NTB-P. Tillage had no effect on crop yield and SOC. Surface residue C and SOC related with grain yield and C content (R2 =0.21-0.55, P = 0.10). Greater amount of crop residue returned to the soil probably increased crop yields and surface residue and soil C storage at surface layers in NTB-P with 40 kg N ha-1. This management practice may also reduce the potentials for soil erosion, N leaching, and pest incidences compared to the traditional system (GRACEnet Publication). |
