Browsing by Author "Dick, Warren"

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    Greenhouse gas fluxes in a no-tillage chronosequence in Central Ohio
    (Elsevier, 2022-04) Bilen, Serdar; Jacinthe, Pierre-Andre; Shrestha, Raj; Jagadamma, Sindhu; Nakajima, Toru; Kendall, Joshua R. A.; Doohan, Thomas; Lal, Rattan; Dick, Warren; Earth and Environmental Sciences, School of Science
    A no-till chronosequence study was conducted to assess the impact of continuous no-till (NT) on greenhouse gases (CO2, CH4 and N2O) emission and the global warming potential (GWP) of agroecosystems. Five paired sites in Central Ohio (USA) under plow till (PT) and NT for 9, 13, 36, 48 and 49 years were selected, and GHG fluxes were measured over a 2-year period. Nearby deciduous forests were included for comparative purposes. Results showed higher CO2 emission under PT than NT (5.74 vs 4.55 Mg CO2-C ha−1). Annual CH4 flux averaged − 0.1 and − 0.07 kg CH4-C ha−1 respectively under NT and PT, and was influenced by location and years under NT (greater rate of CH4 uptake with longer duration of NT). Yet, the rate of CH4 uptake in the agricultural soils was always < 15% of the rate in nearby forest soils (−1.16 kg CH4-C ha−1 y−1). Annual N2O emission was generally higher under PT than NT (6.70 vs 4.68 kg N2O-N ha−1), but an important deviation was observed at one site located on a poorly-drained silt loam soil where N2O emission was 1.8-fold greater under NT than PT, likely due to wet soil conditions and labile organic carbon availability near the soil surface. The GWP of agroecosystems at the study sites averaged 23.1 and 19.9 Mg CO2 equivalents ha−1 y−1 under PT and NT, respectively; N2O emission accounted for 5–60% of the GWP and that contribution increased with NT duration. These results underscore the significance of N2O in defining the climate mitigation potential of agriculture, and also highlight the need for improved N fertilizer management practices (eg. split application, injection) to minimize N2O emission from fields under long-term NT. Even without consideration of agricultural inputs (i.e. fuel, fertilizers, pesticides) and change in soil C storage, the GHG flux data showed that sustained application of NT can help decrease the GWP of agroecosystems, further demonstrating the potential climate mitigation benefits of NT farming.
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    Soil organic carbon pools across paired no-till and plowed Alfisols of central Ohio
    (Wiley, 2016-12) Nakajima, Toru; Shrestha, Raj K.; Jacinthe, Pierre André; Lal, Rattan; Bilen, Serdar; Dick, Warren; Department of Earth Sciences, School of Science
    No-till (NT) farming can restore the soil organic carbon (SOC) pool of agricultural soils, but the SOC pool size and retention rate can vary with soil type and duration of NT. Therefore, the objectives of this study were to determine the effects of NT and soil drainage characteristics on SOC accumulation across a series of NT fields on Alfisols in Ohio, USA. Sites under NT for 9 (NT9), 13 (NT13), 36 (NT36), 48 (NT48) and 49 (NT49) years were selected for the study. Soil was somewhat poorly drained at the NT48 site but moderately well drained at the other sites. The NT48 and NT49 on-station sites were under continuous corn (Zea mays), while the other sites were farmers' fields in a corn–soybean (Glycine max) rotation. At each location, the SOC pool (0–30 cm) in the NT field was compared to that of an adjacent plough-till (PT) and woodlot (WL). At the NT36, NT48 and NT49 sites, the retention rate of corn-derived C was determined using stable C isotope (13C) techniques. In the 0- to 10-cm soil layer, SOC concentration was significantly larger under NT than PT, but a tillage effect was rarely detected below that depth. Across sites, the SOC pool in that layer averaged 36.4, 20 and 40.8 Mg C/ha at the NT, PT and WL sites, respectively. For the 0- to 30-cm layer, the SOC pool for NT (83.4 Mg C/ha) was still 57% greater than under PT. However, there was no consistent trend in the SOC pool with NT duration probably due to the legacy of past management practices and SOC content differences that may have existed among the study sites prior to their conversion to NT. The retention rate of corn-derived C was 524, 263 and 203 kg C/ha/yr at the NT36, NT48 and NT49 sites. In contrast, the retention rate of corn-C under PT averaged 25 and 153 kg C/ha/yr at the NT49 (moderately well-drained) and NT48 (somewhat poorly drained) sites, respectively. The conversion from PT to NT resulted in greater retention of corn-derived C. Thus, adoption of NT would be beneficial to SOC sequestration in agricultural soils of the region.