Quantification of greenhouse gas emissions for carbon neutral farming in the Southeastern USA

• Forest plantations can be used to offset GHG emissions in the Southeast USA.
• Intense crop management had higher total emissions but less per unit product.
• Estimated emissions per unit of crop produced ranged from 0.5 to 3.1 kg CO2e kg−1.
• Most of (90%) of livestock emissions are related to enteric fermentation and manure.
• Estimated area of forest to offset cropland/livestock emissions range from 13 to 27%.

Agriculture is an important source of greenhouse gases (GHG), especially from crop production practices and enteric fermentation by ruminant livestock. Improved production practices in agriculture and increase in terrestrial carbon sinks are alternatives for mitigating GHG emissions in agriculture. The objective of this study was to estimate GHG emissions from hypothetical farm enterprise combinations in the southeastern United States with a mix of cropland and livestock production and estimate the area of forest plantation necessary to offset these emissions. Four different farm enterprise combinations (Cotton; Maize; Peanut; Wheat + Livestock + Forest) with different production practices were considered in the study resulting in different emission scenarios. We assumed typical production practices of farm operations in the region with 100 ha of cropland area and a herd of 50 cows. GHG emissions were calculated regarding production, storage and transportation of agrochemicals (pre-farm) and farm activities such as fertilization, machinery operation and irrigation (on-farm). Simulated total farm GHG emissions for the different farm enterprise combinations and production practices ranged from 348.8 t CO2e year−1 to 765.6 t CO2e year−1. The estimated forest area required to neutralize these emissions ranged from 19 ha to 40 ha. In general, enterprise combinations with more intense production practices that include the use of irrigation resulted in higher total emissions but lower emissions per unit of commodity produced.