Site design
In RockFACE, we run eight full-size FACE rings, 20m in diameter, four with an elevated CO2 concentration (600 parts per million, ppm) and four at the ambient CO2 concentration (~410 ppm). We divide each ring into two halves, with a 3 m buffer zone between them.
One half represents the control ‘no basalt’ treatment and the other receives 40t/ha of crushed basalt, the ERW ‘treatment’.
We first assessed background (pre-treatment) soil status prior to the trials starting by taking soil cores with a Giddings corer down to a depth of ~1m. Soil cores were sectioned according to soil depth, dried, and sieved for initial analysis and measuring pH.
We built and installed small wells to a depth of ~150 cm for sampling soil water throughout the season, in addition to installing lysimeters, essentially small tubes allowing shallower soil water sampling (depth of ~50 cm) under vacuum. We installed soil moisture and respiration collars in both halves of all four FACE rings.
We buried replicated sets of mesh-bags filled with washed basalt grains for recovery after 1, 2, and 3 years. These will be subject to wet chemistry to determine extent of cation loss and by mass balance carbon dioxide removal.
We applied basalt (pioneer valley) and tilled it into the soil in November 2021 and the field laid fallow until May 2022. A commercial maize cultivar was planted in all eight rings on May 12, 2022. Fumigation with elevated CO2 in four rings began on May 20 2022. In November 2022, we applied basalt a second time and will plant a commercial soybean cultivar in Spring 2023.