The long-term impact of vehicular traffic on winter and spring methane flux under no-till farming in Central Ohio

Abstract

Mechanized conservation agriculture, mainly no-till (NT) based production systems, is of utmost importance for the conservation of natural resources and restoration of the environmental quality. However, the impact of machine-induced compaction on the methane (CH4) uptake in the absence of the growing crop is not known. Emission of CH4 from soil to the atmosphere through anthropogenic activities plays a significant role in global climate change. Thus, a NT compaction experiment was established at the Waterman Farm of the Ohio State University, Columbus, Ohio, in 1997, to study the long-term impact of the growing season traffic on non-growing season methane emission under NT farming. The levels of traffic included: control (no passages with additional axle loads; VT-0), two (VT-2) and four (VT-4) additional passages of 2.5 Mg water wagon axle load to cover the entire plot. To study the CH4 uptake capacity of soil under NT in relation to natural soils, three locations were also selected from the adjoining woodlot (WL). The CH4 emissions of soil were monitored between November 16, 2016 and May 30, 2017. CH4 emissions ranged from −8.54 to 5.06 mg m−2 day−1 with mean of −0.97, −0.45, −1.31 and −4.46 mg CH4 m−2 day−1 for VT-0, VT-2, VT-4 and WL, respectively. The CH4 uptake was higher in soil under WL -4.85, and −3.07 mg CH4 m−2 day−1 during winter and spring seasons, respectively than under other treatments. The VT-2 treatment recorded the highest CH4 emission (0.55 mg CH4 m−2 day−1) during winter and the lowest soil CH4 uptake (−1.19 mg CH4 m−2 day−1) during the spring season. At end of the study, the cumulative uptake of CH4 was reduced under VT-2 by 911% and 122% as compared to that in soil of WL (5.36 CH4 kg ha−1) and VT-0 (1.18 CH4 kg ha−1), respectively. The radiative forcing (RF) i.e. greatest net CH4 emissions were observed under VT-4. The study concluded that long-term (>20 years) use of 2 or 4 additional passages of traffic 2.5 Mg axle load under NT farming reduced the oxidation and uptake rate of CH4 in comparison to that of soil under NT and WL, which may consequently reduce the CH4 mitigation potential of NT soils.