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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #350144
Title: Carbon budget calculation for agroforestry systems

Author
item DOLD, CHRISTIAN - Orise Fellow
item THOMAS, ANDREW - University Of Missouri
item Ashworth, Amanda
item PHILIPP, D - University Of Arkansas
item ADAMS, T - University Of Arkansas
item Sauer, Thomas

Submitted to: Temperate Agroforester
Publication Type: Other
Publication Acceptance Date: 2/23/2018
Publication Date: 4/30/2018
Citation: Dold, C., Thomas, A.L., Ashworth, A.J., Philipp, D., Adams, T.C., Sauer, T.J. 2018. Carbon budget calculation for agroforestry systems. Temperate Agroforester. 24(1). Available: https://www.aftaweb.org/136-2018-vol-24/2018-vol-24-no-1/229-carbon-budget-calculation-for-silvopastoral-systems.html

Interpretive Summary: Climate-smart agriculture means the reduction of greenhouse gas emissions in agricultural production. Agroforestry systems (AFS) in temperate regions can be "climate-smart", because these systems can store high amounts of carbon. In this article, we present first results of carbon inputs and outputs for an 18-year-old pecan silvopasture (that is, trees, forages, and/or livestock in the same area) in Fayetteville, AR. The largest amount of carbon was found in the soil with 46,541 lb carbon per acre, followed by trees (without leaves) with 2,642 lb carbon per acre. The bulk of soil and tree carbon is stored long-term in the AFS, because decomposition rates of woody material and in soils under sustainable management are generally slow. Approximately 419 lb carbon per acre exits the AFS as pecan nuts. Carbon in tree leaves was 502 lb per acre, but is not considered for long-term carbon storage, because tree leaves are easily decomposed. Carbon in forages after grazing was 1508 lb per acre, a part of which may contribute to long-term carbon storage as standing biomass or litter. Forage litter measurements were not included, but can accumulate substantial amounts on the soil surface. For now, we only consider carbon uptake from trees in woody material with an estimated rate of +155 lb carbon per acre per year. We still lack information on other carbon sources, such as roots, carbon mineralization in soil, forage, and trees, and the inputs and outputs of livestock. Therefore, future work will include the excavation of tree and forage roots to analyze carbon, as well as the measurement of gaseous carbon inputs/outputs of pastures, trees, and soils. This research is of importance for stakeholders, who are interested in calculating carbon inputs and outputs in their agricultural systems.

Technical Abstract: Climate-smart agriculture comprises production systems, which, among other objectives, help reduce greenhouse gas emissions. Agroforestry systems (AFS) have recently drawn attention as climate-smart production systems for temperate regions, as they can provide high net carbon (C) gains per area, and generally occupy a relatively small fraction of the agricultural landscape. In this article, we present first results of a C budget calculation for an 18-year-old pecan silvopasture in Fayetteville, AR, and outline future efforts to estimate missing pieces of the C budget. The largest C pool is the soil with 46,541 lb C per ac, followed by woody tree material with 2,642 lb C per ac. The bulk of soil C and wood C make up the long-term C storage pool, because decomposition rates of woody material and in soils under sustainable management are generally slow. Approximately 465 lb C per acre leaves the AFS as nuts. Tree leaves and forage yield was 502 and 1508 lb C per acre, respectively. Both are not considered for long-term C storage, because tree leaves are easily decomposed, and forages are grazed by cattle. Forage litter was not included, but can accumulate substantial amounts on the soil surface. For now, we only consider above-ground tree C sequestration in woody material with an estimated rate of +155 lb C per acre and year. We still lack information on other C pools and fluxes, such as roots, respiration of soil, forage, and trees, and the inputs and outputs of livestock. Therefore, future work will include the excavation of tree and forage roots to analyze C, as well as the measurement of CO2 fluxes of pastures, trees, and soils with eddy flux stations and automated chambers.