Scientific goals

Our scientific goal is to investigate the potential for elevated atmospheric CO2 (at 600 ppm) to interact with crops, soils and rock grain biogeochemistry to accelerate ERW and carbon dioxide sequestration and feedback on improved plant performance.

A photo showing one of the enrichment rings at the RockFACE site

Over a maize/soybean crop rotation across four growing seasons, we are testing four core ERW-elevated CO2 research hypotheses:

  1. Reduced stomatal conductance of soybean leaves (and to lesser extent in maize) with CO2 enrichment reduces canopy transpiration, which increases soil moisture to increase ERW.
  2. Increased shallow root biomass, and resulting rhizosphere respiration rates, increase ERW.
  3. Increased soybean nodulation leads to greater localized acidification around rock grains and increase ERW.
  4. ERW reverses reductions in the elemental nutrient concentrations of C3 and C4 crop grains observed under CO2 enrichment that are important for human nutrition (e.g., iron and zinc).
See a close up of the ring operating in the FACE trial

We’re measuring:

  • LAI (leaf area index), which tells us about crop development

  • Photosynthesis/stomatal conductance, important for feedbacks on soil moisture and productivity

  • Soil respiration, a potential loss pathway for CO2.

  • Soil N2O, an important non-CO2 greenhouse gas.

  • Soil moisture content, important for rock grain weathering.

  • Water chemistry from wells, i.e. products of carbon capture.

  • Final yield harvest to determine yield responses.

  • Shallow soil cores after harvest for measuring pH and cation exchange capacity responses.

  • Rates of in situ rock grain weathering.

  • Crop nutritional status for grain quality and nutritional status.