Short‐term grazing of cover crops and maize residue impacts on soil greenhouse gas fluxes in two Mollisols
Navdeep Singh, Gandura Omar Abagandura, Sandeep Kumar
Abstract
Abstract An integrated crop–livestock system (ICLS), when managed properly, can help in mitigating soil surface greenhouse gas (GHG) fluxes, especially carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O). However, the impacts of an ICLS on GHG fluxes are poorly understood. The present study was conducted at two sites (northern Brookings [Brookings‐N] and northwestern Brookings [Brookings‐NW]) established in 2016 and 2017, respectively, under loamy soils in South Dakota. The specific objective was to evaluate the impact of cover crops (CCs) and grazed CCs under oat ( Avena sativa L.)–CCs–maize ( Zea mays L.) rotation on GHG fluxes. Study treatments included the following: (a) a legume‐dominated CC (LdC), (b) a cattle‐grazed LdC (LdC+G), (c) a grass‐dominated CC (GdC), (d) a cattle‐grazed GdC (GdC+G), and (e) one without CC or grazing (NC). Greenhouse gas monitoring occurred weekly during the growing crop seasons in 2016 and 2017 for Brookings‐N and in 2017 and 2018 for Brookings‐NW. Data showed that cumulative CO 2 and N 2 O fluxes at Brookings‐N were lower for GdC+G (4042 kg C ha −1 for CO 2 and 1499 g N ha −1 for N 2 O) than for LdC+G (4819 kg C ha −1 for CO 2 and 2017 g N ha −1 for N 2 O), indicating the superiority of GdC+G over LdC+G in reducing GHG fluxes. However, no effect from grazed CC on cumulative CO 2 and N 2 O fluxes were observed at the Brookings‐NW site. Cumulative CH 4 flux was not affected by an ICLS at either site. This short‐term investigation showed that, in general, CCs and grazing of CCs and maize residue did not impact GHG fluxes.