Soil Surface Greenhouse Gases in an Integrated Crop-Livestock System in South Dakota, USA.

ABSTRACT

The specialized intensification of crops and livestock production has negatively impacted soils and the environment. Integrated crop-livestock system (ICLS) is one of the alternative managements that can reduce the problems. However, the impacts of ICLSs on soil surface greenhouse gas (GHG) emissions have not been well documented. The objective of this study was to monitor soil GHG fluxes including carbon dioxides (CO₂), methane (CH₄), and nitrous oxide (N₂O) for evaluating impacts of ICLS on the environment. The experiment was a randomized complete block design with 4 replications at Beresford site in South Dakota. The treatments were (i) corn (Zea mays L.)-soybean (Glycine max L.)-rye (Secale cereal L.) (control), (ii) corn-soybean-rye/cover crops, and (iii) corn-soybean-rye/cover crops with grazing. GHGs were sampled using static chamber method at three-time intervals over 40 minutes (0, 20, 40 minutes). The sample collection was weekly conducted throughout the growing season (July through November) in 2016. The Gas Chromatography (GC) was used to measure concentrations of CO₂, CH₄, and N₂O, and then calculate the fluxes based on these concentrations. The results showed that N₂O fluxes were not influenced by the rotation, but were significantly impacted by the grazing treatment. The mean N₂O fluxes were significantly higher under the grazing treatments compared with the ungrazed. The rotation and grazing treatments did not have significant effects on the CO₂ and CH₄ fluxes. The impacts of the time on the CO₂ and N₂O fluxes were significant.