ENABLING MANAGEMENT RESPONSE OF SOUTHEASTERN AGRICULTURAL CROP AND PASTURE SYSTEMS TO CLIMATE CHANGE
Location: National Soil Dynamics Laboratory
Title: Influence of Elevated Atmospheric CO2 and Tillage Practice on Rainfall Simulation
Submitted to: Southern Conservation Agricultural Systems Conference
Publication Type: Proceedings
Publication Acceptance Date: July 20, 2010
Publication Date: July 20, 2010
Citation: Prior, S.A., Watts, D.B., Arriaga, F.J., Runion, G.B., Torbert III, H.A., Rogers Jr, H.H. 2010. Influence of Elevated Atmospheric CO2 and Tillage Practice on Rainfall Simulation. In: Conservation Agriculture Impacts-Local and Global, Proceedings of 32nd Southern Conservation Agricultural Systems Conference, July 20-22, 2010, Jackson, Tennessee. P. 83-88. CD-ROM.
Interpretive Summary: It is unknown if increases in atmospheric CO2 concentration will impact loss of soil in agricultural systems. Following a 10 year study examining the effects of elevated CO2 in two cropping systems (conventional tillage and no-till), we investigated sediment loss using simulated rainfall. Both systems included a grain sorghum and soybean rotation. The no-till system also included crimson clover, sunn hemp and wheat as winter cover crops. Soil surface residue was increased by high CO2, especially in the no-till system. The higher residue under no-till increased water infiltration. Loss of soil was low under no-tillage regardless of CO2 level, but elevated CO2 did decrease soil loss only under conventional tillage. Findings suggest that both high CO2 and no-tillage increased surface residues which can improve water infiltration and reduce soil loss.
No work has investigated whether increasing atmospheric CO2 concentration will impact sediment loss in agricultural systems. Rainfall simulation was conducted following a 10-year study investigating the effects of atmospheric CO2 level (ambient and twice ambient) in two cropping systems (conventional tillage and no-tillage) on a Decatur silt loam (clayey, kaolinitic, thermic Rhodic Paleudults). The conventional system consisted of a sorghum [Sorghum bicolor (L.) Moench.] and soybean [Glycine max (L.) Merr.] rotation using spring tillage and winter fallow. The no-tillage system used this rotation along with three rotated cover crops [crimson clover (Trifolium incarnatum L.), sunn hemp (Crotalaria juncea L.), and wheat (Triticum aestivum L.)] without tillage. Elevated CO2 increased residue in both tillage treatments, with the effect being greater under no-tillage. This resulted in increased water infiltration only under no-tillage. Overall, sediment loss was low under no-tillage regardless of CO2 level; therefore, elevated CO2 decreased sediment loss only under conventional tillage. Our results showed that both high CO2 and no-tillage increased surface residues; this can improve water infiltration and reduce soil loss.