Life Cycle Greenhouse Gas Emissions in Maize No-Till Agroecosystems in Southern Brazil Based on a Long-Term Experiment

Abstract

Brazilian agriculture is constantly questioned concerning its environmental impacts, particularly greenhouse gas (GHG) emissions. This research study used data from a 34-year field experiment to estimate the life cycle GHG emissions intensity of maize production for grain in farming systems under no-tillage (NT) and conventional tillage (CT) combined with Gramineae (oat) and legume (vetch) cover crops in southern Brazil. We applied the Feedstock Carbon Intensity Calculator for modeling the “field-to-farm gate” emissions with measured annual soil N2O and CH4 emissions data. For net CO2 emissions, increases in soil organic C (SOC) were applied as a proxy, where the CT combined with oat was a reference. The life cycle GHG emissions intensity for maize was negative under NT farming systems with Gramineae and legume cover crops, −0.7 and −0.1 kg CO2e kg−1 of maize, respectively. CT with oats as a cover crop had a GHG intensity of 1.0 kg CO2e kg−1 of maize and 2.2 Mg CO2e ha−1. NT with cover crops increased SOC (0.7 C Mg ha−1 yr−1, 0–100 cm) and contributed to the mitigation of life cycle GHG emissions of maize production. This research shows that NT with cover crops is a sustainable solution for farming in southern Brazil.