Addressing soil nutrient degradation and global warming requires novel solutions. Enhanced weathering using crushed basalt rock is a promising dual-action strategy that can enhance soil health and sequester carbon dioxide. This study examines the short-term effects of basalt amendment on spring oat ( Avena sativa L .) during the 2022 growing season in NE England. The experimental design consisted of four blocks with control and basalt-amended plots, and two cultivation types within each treatment, laid out in a split plot design. Basalt (18.86 tonnes ha −1 ) was incorporated into the soil during seeding. Tissue, grain and soil samples were collected for yield, nutrient, and pH analysis. Basalt amendment led to significantly higher yields, averaging 20.5% and 9.3% increases in direct drill and ploughed plots, respectively. Soil pH was significantly higher 256 days after rock application across cultivation types (direct drill: on average 6.47 vs. 6.76 and ploughed: on average 6.69 vs. 6.89, for control and basalt-amended plots, respectively), likely due to rapidly dissolving minerals in the applied basalt, such as calcite. Indications of growing season differences in soil pH are observed through direct measurement of lower manganese and iron uptake in plants grown on basalt-amended soil. Higher grain and tissue potassium, and tissue calcium uptake were observed in basalt-treated crops. Notably, no accumulation of potentially toxic elements (arsenic, cadmium, chromium, nickel) was detected in the grain, indicating that crops grown using this basaltic feedstock are safe for consumption. This study indicates that basalt amendments can improve agronomic performance in sandy clay-loam agricultural soil under temperate climate conditions. These findings offer valuable insights for producers in temperate regions who are considering using such amendments, demonstrating the potential for improved crop yields and environmental benefits while ensuring crop safety.

Amendment

10.1371/journal.pone.0295031

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Application of an Innovative Centrifuge-Based Soil Pore Water Sampling Method in Basalt Enhanced Weathering Field Trials.

Anežka Borčinová Radková Xinran Liu Tzara Bierowiec E. J. Chen Ifeoma Edeh

Basalt Enhanced Weathering as a Carbon Dioxide Removal (CDR) technology accelerates natural weathering, enhancing the CO2 removal from the atmosphere. The main objective of the ongoing field trials in Scotland and the UK is to combine geochemistry modelling with in-field measurement to most accurately quantify CO2 sequestration. To measure the weathering signal in the field, we track changes in indicators such as soil inorganic carbon (SIC), soil organic carbon (SOC), exchangeable cations, trace/immobile elements, and soil biomass. Pore water analysis is critical for directly quantifying CO2 sequestration. Bicarbonate in soil pore water is a  CO2 removal indicator, as it forms through the reaction of silicate minerals with dissolved CO2 during the initial weathering process. We analyze pore water for pH, alkalinity, Electrical Conductivity (EC), major cations, and anions. This task can be challenging due to sampling issues, the absence of rainfall, and the time-sensitive nature of alkalinity measurements. Analyses of pore water chemistry rely on the ability to separate water from solids with minimal modification of its chemistry. Rhizon samplers and ceramic lysimeters are commonly used for pore water extraction. They may not be ideal for parameters like pH and alkalinity due to certain limitations, such as degassing of dissolved gases, and biases in molecule diffusion through the membrane. In response, we are testing a centrifuge method for pore water sampling from basalt amended fields. In the initial trial, statistical significance tests were conducted to compare the pH and total alkalinity between control plot and Treatment 126 t/ha in both centrifuge and rhizon samples, revealing a statistically significant difference (p < 0.05) in values within the centrifuge samples. However, no significance was observed in the rhizon samples. We present the results of ongoing tests from different treatments and soil types conducted to investigate whether centrifuge would be a suitable method for pore water sampling and alkalinity measurement for the enhanced weathering field trials.

Centrifuge

10.5194/egusphere-egu24-20843

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Initial agronomic benefits of enhanced weathering using basalt: A study of spring oat in a temperate climate

Kirstine Skov Jez Wardman Matthew Healey Amy McBride Tzara Bierowiec

Addressing soil nutrient degradation and global warming requires novel solutions. Enhanced weathering using crushed basalt rock is a promising dual-action strategy that can enhance soil health and sequester carbon dioxide. This study examines the short-term effects of basalt amendment on spring oat (Avena sativa L.) during the 2022 growing season in NE England. The experimental design consisted of four blocks with control and basalt-amended plots, and two cultivation types within each treatment, laid out in a split plot design. Basalt (18.86 tonnes ha −1 ) was incorporated into the soil during seeding. Tissue, grain and soil samples were collected for yield, nutrient, and pH analysis. Basalt amendment led to significantly higher yields, averaging 20.5% and 9.3% increases in direct drill and ploughed plots, respectively. Soil pH was significantly higher 256 days after rock application across cultivation types  (direct drill: on average 6.47 vs. 6.76 and ploughed: on average 6.69 vs. 6.89, for control and basalt-amended plots, respectively), likely due to rapidly dissolving minerals in the applied basalt, such as calcite. Indications of growing season differences in soil pH are observed through direct measurement of lower manganese and iron uptake in plants grown on basalt-amended soil. Higher grain and tissue potassium, and tissue calcium uptake were observed in basalt-treated crops. Notably, no accumulation of potentially toxic elements (arsenic, cadmium, chromium, nickel) was detected in the grain, indicating that crops grown using this basaltic feedstock are safe for consumption. This study indicates that basalt amendments can improve agronomic performance in sandy clay-loam agricultural soil under temperate climate conditions. These findings offer valuable insights for producers in temperate regions who are considering using such amendments, demonstrating the potential for improved crop yields and environmental benefits while ensuring crop safety.

10.5194/egusphere-egu24-1421

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Preliminary findings from comparison of in-situ measurements of enhanced weathering proxies with model predictions

Kirstine Skov Tzara Bierowiec Ifeoma Edeh Mike Kelland Amy Lewis

Enhanced weathering of silicate rock is a promising natural carbon dioxide removal technology, both due to its scalability and associated agronomical benefits. During silicate rock weathering, dissolved carbon dioxide in the form of carbonic acid, reacts with rock minerals to form stable soil pore water bicarbonate or soil calcium carbonate. The carbon dioxide removal potential of enhanced weathering has been successfully demonstrated in short-term lab and mesocosm studies. Due to the transient nature of bicarbonate in the aqueous soil solution, in-field quantification of the carbon dioxide sequestered is tedious, labour-intense and poorly scalable for the verification of carbon credits. Various methods have been suggested in order to quantify the amount of carbon dioxide sequestered through rock weathering. This quantification is essential for verification bodies to award carbon credits. Although various methods have been proposed to demonstrate that in-field weathering is occurring, there is still no consensus for a scalable, profitable solution. In recent years, an increasing number of field trials have seen the light of day. However, large uncertainties about in-field weathering rates and the influence of natural environmental variability, such as drought and vaying temperatures, still exist.  In this study we focus on two proxies affected by the weathering process, namely pH and EC. We compare field measurements of pH and EC from both in-situ sensors and extracted soil pore water with model predictions from a 1D-reactive transport model. The data originates from an ongoing field trial on an acidic, clay rich soil used for grassland pasture in central Scotland. Such in-field proxy measurements may provide information to help boost confidence in model predictions.

Carbonic acid

Bicarbonate

Mesocosm

10.5194/egusphere-egu23-13354

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