Greenhouse Gas Fluxes from Intercropped and Sole Cropped Agroecosystems in Argentina.

Human activities are increasing greenhouse gas (GHG) concentrations in the atmosphere. Slowing the accumulation of GHG in the atmosphere is expected to require efforts from many sectors of the economy. Agriculture is one of the sectors that could contribute to this effort by enhancing the carbon (C) and nitrogen (N) sink in soil. It has been suggested that the Argentine Pampas is one of the global regions with a high potential to sequester C. In Argentina, soybean crops have high economic return, and cultivation has increased from 5 to 14.5 million hectares in the last 10 years. However, soybeans have lower biomass productivity and therefore low C return to the soil, and intensive sole cropping may result in soil degradation and lowered soil organic matter (SOM). We hypothesize that complex agroecosystems, such as maize-soybean intercrops have the potential for reducing GHG emissions and sequester C in the soil. In this study, CO₂, CH₄ and N₂O emissions in two maize-soybean intercrop agroecosystems, a maize sole crop and a soybean sole crop were measured. The experimental site at Balcarce, Argentina (37º 45´S, 58º 18´W; elevation 130 m) was a randomized complete block design (RCBD) with 3 replications. Soil samples were taken in increments to a 120 cm depth and analyzed for C and N. Soil C- and N-input from crop residue was determined by sampling maize and soybean biomass at harvest. Results from this work will contribute information on how to meet food production needs while promoting a reduction in GHG emissions and how complex agroecosystems will respond to future climate change.