Theme 3 blog update: Illinois Energy Farm update 2016-2025
Our field trials are an integral part of the LC3M project, and form the backbone of our Theme 3: Applied weathering science. Here we catch up with the progress on our Energy Farm field site in Illinois, USA, from 2016 to 2025.
The 90 million hectares of maize and soybean in the US Midwest, forming the Corn Belt, is arguably the single largest ecosystem type in the USA. Our large-scale field experiments are exploiting the unique Energy Farm facility, in the heart of the Corn Belt.
The objective of research at the University of Illinois is to examine the effect of basalt application on the carbon and nutrient balance of traditional row crop agriculture in the US Midwest – maize/soybean rotation – and a high- yielding perennial bioenergy crop – Miscanthus x giganteus. Trials are being undertaken in paired adjacent 3.8 ha plots (plus or minus basalt) with corn-soy rotation or the bioenergy crop Miscanthus, over multiple years.
We are capturing the effects of crops on basalt weathering through analysis of leachate from each plot, which is automatically collected by tile drains at a single location, and its feedback on crop performance using tower mounted eddy co-variance systems. In addition to analysis of leachate, rates of basalt weathering and carbon dioxide removal are estimated by geochemical analysis of the soil.
Catch up with progress below, including relevant publications, since our inception in 2016.
Jump to:
- 2016-2017
- 2017-2018
- 2018-2019
- 2019-2020
- 2020-2021
- 2021-2022
- 2022-2023
- 2023-2024
- 2024-2025
- Papers featuring our Illinois trials
2016-2017
A pilot study of basalt application was conducted during the growing season in 2016 with 2x2m basalt-treated plots in maize, soybean, and miscanthus. Finding promising results with basalt application, we expanded the pilot studies initiated in 2016 to field scale for 2017 in maize. Replicate control and experimental plots (4 x 0.7 ha and 1 x 3.8 ha plot for each control and experimental group and for each crop type) were established in the autumn of 2016 after crop harvest. We collected soil water from drainage tiles (1.5 m-depth) installed under the 3.8-ha plots to facilitate the chemical analysis of drainage water; and eddy covariance towers in the centre of each large plot measured surface-atmosphere exchange of carbon, water, and energy.
In 2016, we identified a basalt vendor for Blue Ridge metabasalt and ground material was applied at 5 kg m-2 to the maize/soybean plots in autumn 2016 and tilled into the soil during the postharvest cultivation in the first of four annual applications. We’ve been taking weekly measurements of trace gas fluxes from soil and monthly soil pH analysis. Soil, plant tissues, and soil water will be chemically analyzed for agriculturally-important by-products of basalt weathering, so we can predict effects on soil fertility and plant tissue quality. Strontium isotope analysis will track the rate of basalt weathering in the system. We’ll be using the eddy flux measurements of carbon fluxes to calculate carbon storage, and combining these with measurements of latent heat flux to calculate water use efficiency. We are quantifying the direct effect of basalt application on soil fertility by periodic measurements of soil pH, and calcium and magnesium ions, with above- and belowground biomass and plant tissue analysis to determine the effects on crop yield and quality. Baseline measurements of eddy covariance, soil respiration, and biogeochemical measurements are underway in M x giganteus plots. Basalt will be applied to M x giganteus in the spring of 2018.
2017 -2018
The 2017 research season began with the first field-scale application of basalt to the Energy Farm plots at the University of Illinois. 198 metric tons of crushed rock sourced from Pennsylvania were tilled into the maize fields equipped for measuring soil respiration and nitrous oxide production, for collecting soil water, and measuring the exchange of CO2 and water vapour between soil and the atmosphere. Soil collected throughout the season was analysed for soil pH, carbon, and nitrogen, while peak season and end-of-season tissue sampling provided biomass and nutrient content in the crop. Grain harvest analysis indicated a significant 15% increase in maize following the basalt application (see below).
Sampling equipment in tile drains beneath the 3.8-ha fields at the Energy Farm measured water flow rates and sampled water flowing through the vadose zone to calculate the total chemical weathering rates of the 3.8 ha plots. More than 10 million litres of drainage water passed through the sampling system in 2016-2017. During the past year, water and soil samples collected over the 2016/17 and 2017/18 growth cycles have been analysed for geochemical parameters pertinent to chemical weathering. In total, ~200 tile drain water samples, ~90 soil pore water samples collected from tension lysimeters, and ~10 precipitation samples have been measured for major cation and anion concentrations. An additional ~40 tile drain water samples have been analysed for alkalinity, DOC, and nutrient concentrations, and ~50 samples have been analysed for 87Sr/86Sr ratios. Soil pore water molar Ca/Sr ratios suggest that carbonate weathering in the basalt increased in the maize subplots treated with basalt. The next steps are to measure the 87Sr/86Sr ratios in soil pore water and plant samples to identify whether there is a basalt weathering signal in these reservoirs, as well as to calculate 2017/18 chemical weathering rates.
In 2017 the emission of N2O, an important greenhouse gas produced by soil microbes, was reduced in basalt-treated maize plots by 40% compared to controls (see below), as previously observed in the 2016 pilot study. As N2O production from soil represents a loss of nitrogen that would fertilize crops, reduced N2O emissions are a potential benefit to both atmosphere and agriculture. We found that soil pH increased more rapidly in basalt-treated maize plots after application than in controls in 2017, and pH remained higher in basalt-treated plots at the end of the growing season. Initial measurements for 2018 indicate that the trend is continuing in the second year of basalt treatment. N2O and yield data are being used with the DayCent ecosystem model to understand the effects of long-term basalt application on greenhouse gas balances and agricultural productivity. These models will link through to our Earth system modelling and are informed by years of data from the Energy Farm, and can be adjusted for other regions by changing soil properties, climate conditions, and crop characteristics.
2018-2019
In the 2018 research season, we expanded basalt application to encompass both annual maize and mature perennial miscanthus plots at the University of Illinois Energy Farm. Maize basalt application and tillage occurred in the autumn, after the 2017 harvest, and basalt was surface-applied to miscanthus before plant emergence in the spring of 2018. Measurements of greenhouse gas production from soils, soil carbon and nitrogen, and plant biomass and yield were carried out through the growing season, while eddy covariance towers monitored gas exchange for each of the crops.
Water samples (tile drain water, soil pore water and rain) were collected throughout the year and analysed for pH, electrical conductivity, alkalinity, major cation and anion concentrations, dissolved organic carbon concentrations, total dissolved nitrogen concentrations and radiogenic Sr isotope (87Sr/86Sr) ratios.
Measurements in 2018 confirmed that, like maize, soils under miscanthus respond to basalt application with increased pH and reduced soil N2O production (see below), though total N2O production from control and basalt-treated miscanthus is only about a tenth of that produced by heavily-fertilized maize. Biogeochemical models, validated with observations of productivity, and greenhouse gas measurements for the region, indicate that basalt-induced pH change is the major driver of differences in N2O production, with basalt-supplied phosphorus as the secondary driver.
Measured strontium isotope ratios (87Sr/86Sr) of maize water reservoirs (soil water and drainage water) in the experimental plots were shifted to lower values compared to the corresponding samples from untreated control plots in 2017 and 2018, but these are not currently statistically significant. Nevertheless, the direction of change in both years may be consist with some basalt weathering (see below). Future work will measure the 87Sr/86Sr ratios of soil exchange sites as a possible reservoir for weathered basalt cations. Measured 87Sr/86Sr ratios of 2018 miscanthus water reservoirs, and above-ground biomass reservoirs, from the control and experimental plots (2018 was the first year of treatment) encompass a narrow range of values and are statistically identical to their corresponding 2017 values when no basalt was applied (see comparisons below).
The 2019 season began with basalt application to maize/soybean fields in November of 2018, and continued with basalt application to miscanthus and the first full-scale planting of basalt-treated soybean in May 2019.
2019-2020
The 2019 research season marked the first year of soybean production in the basalt-treated maize/soybean fields as part of scheduled crop rotation at the Energy Farm. Basalt application and tillage of maize/soy fields occurred in the autumn after the 2018 maize harvest, and basalt was surface-applied to miscanthus before plant emergence in the spring of 2019. Measurements of plant productivity, soil and soil water chemistry, and greenhouse gas production from soils continued through the growing season. Soil and soybean roots and nodules were collected in 2019 to investigate nitrogen cycle microbial community responses to basalt application (see photos below).
Field measurements in 2019 confirmed that nitrogen fertiliser is the source of much of the N2O produced in these systems — in 2019, when unfertilised soybeans were planted in place of heavily fertilised maize, site-wide N2O production was extremely limited in both control and basalt-treated plots. Miscanthus, fertilized at 1/3 the rate of maize, cycles nitrogen more tightly, resulting in lower N2O emissions overall, comparable to unfertilised soybeans. A major focus of the 2019 research was to investigate the potential mechanisms that reduced N2O production with basalt, particularly soil pH and phosphorus supply (see below).
Through collaboration with Dr Maria Val Martin, we assessed the regional impact of amending soils throughout the Midwestern US with basalt by implementing the calibrated DayCent function relating soil pH to changes in nitrogen cycling in the Community Land Model (CLM). Process-based upscaling of our field-trial results indicates reductions from the baseline flux of 0.3 ± 0.02 Tg N2O-N yr-1 by 6, 17, 27 and 43% across the Midwest following increases in initial soil pH by 0.1, 0.3, 0.5, and 1.0 units, respectively (see below), with substantial reduction occurring in areas where croplands dominate. In particular, the area under intense maize/soy production showed the largest responses to changes in the model parameters.
We’ve carried out preliminary assessments of the quantities of carbon dioxide removal through (i) alkalinity generation and (ii) formation of pedogenic carbonate. Removal of CO2 through alkalinity generation is strongly controlled by discharge. As the tile drain systems do not record all of the discharge from the experimental plots, a key focus of our work in 2020 will be to better quantify the hydrological mass balance at the Energy Farm. While concentrations of carbonate are very low in all of the soils at the Energy Farm, analyses of the stable carbon isotopic composition of the soils reveals that carbonates are present. In 2020 we will focus on quantifying the pedogenic carbonate content of soils from control vs basalt-treated plots.
2020-2021
In 2020, the first publication of measured and modelled mitigation of N2O emissions by the ERW treatment at the Energy Farm was published (Blanc-Betes et al., 2020). The results showed an interaction of the pH-raising effects of basalt application and the addition of small amounts of phosphorus from the basalt, a nutrient that is depleted over time by annual row crop agriculture. In agricultural soils, pH is often managed by the addition of agricultural lime, which is primarily calcium carbonate, and results in a release of CO2 to the atmosphere. The basalt model results show that the pH change and phosphorus addition from basalt exceeds the effect of pH manipulation alone on N2O production.
Measurements of biomass production in 2020 showed an increase in peak biomass production in annual crops for the second year in a row: 2019 in soybean (16%) and 2020 in maize (12%). Additionally, we observed an increase in peak biomass miscanthus (42%), similar to increases observed in 2018 (30%). Throughout the course of the experiment, biomass in basalt-treated plots has consistently met or exceeded production in basalt-free controls in both conventional row crops and perennial grasses.
In 2020, we continue to see the increased influence of silicate weathering in basalt treated plot soil waters (see below). Initial results indicate that small quantities of soil carbonate, which represent a sink of atmospheric CO2, may be forming in basalt-amended plots. Work to confirm this, including sampling of deep soils, is ongoing. Method development has been carried out such that work to quantify soil ‘health’ and soil inorganic carbon is currently underway, using a sequential extraction method. This will include measurement of soil available trace metal and micronutrients.
We completed soil and root collection for microbial sequencing of basalt-treated corn soils in July of 2020. This work follows successful sampling and sequencing of basalt-treated soybean in 2019, with the intent of understanding the composition and dynamics of the microbial community responsible for nitrogen cycling in basalt-treated soils.
In autumn 2020/spring 2021, all basalt plots received the first applications of “Pioneer Valley” basalt, replacing the “Blue Ridge” basalt used the previous four years. N2O collection continues in control, basalt, and limed soils in maize. Our measurements in 2020 showed large nitrogen losses from limed soils, but the timing of lime application confounded examination of the mechanisms of N2O production. In 2021, continued measurements will compare the effect of soil pH change alone with basalt-induced pH change. N2O collection continues in miscanthus, where basalt is surface-applied.
Basalt-filled mesh bags buried in the research plots will expose basalt grains to the weathering effects of the soil and plant environment, while conserving basalt particles for microscopic examination and analysis of weathering progression using x-ray powder diffraction (XRD) on individual grains of basalt material. Bags will be installed in 2021 in both cropping systems for removal after one, two, and three years of weathering.
2021-2022
Basalt plots at the University of Illinois Energy Farm received their second applications of Pioneer Valley basalt in Autumn 2021/Spring 2022. We’re continuing to collect soil, plant biomass, and tile drain water. Rooting zone soil water collection, which has been limited during the growing season in previous years due to dry soils, was improved in the spring of 2022 with the installation of passive soil water wells, which replace tension lysimeters. These wells sample deeper in the soil profile, and early results indicate that they are collecting more water than the previous year’s lysimeters as the growing season approaches.
In 2021-22, an effort to complete a full carbon budget for the Energy Farm under ERW has combined soil samples, plant samples, and soil respiration measurements to determine the rates of basalt weathering and carbon sequestration in the two crop systems. While the organic carbon dynamics of the Energy Farm have been extensively studied, inorganic carbon was a very small fraction of the total soil carbon prior to the addition of basalt. The carbon budget is being re-evaluated with special focus on the inorganic products of ERW.
Soil samples from maize/soy fields from the Energy Farm are being analysed for rare earth elements (REE) and other key elements to track the incorporation of basalt into the soil. REE are adsorbed by soil organic matter and are retained in the topsoil, allowing measurements of REE to be used as a proxy for measurements of basalt. Soil from 2016 (pre-basalt), 2020 (four years post-Blue Ridge basalt) and 2021 (one year post-Pioneer Valley basalt) will be analysed for fifteen rare earth elements and 12 non-REE elements and compounds. Differences between baseline soils and basalt-amended soils will be used to calculate the weathering rate of basalt and the carbon capture potential of the system.
Over the past year we have developed a new collaboration with Dr Noah Planavsky and his team at the Department of Earth & Planetary Sciences, at Yale University, who are working on empirical estimates of CO2 removal potential based on measuring cation loss from basalt in soils, i.e., forward weathering reactions. Success of the approach hinges on accurate measurement of basalt cation loss from soils (by chemical weathering) and this aspect is aided by the application of isotope-dilution mass spectrometry, essentially a modified version of the idea originally developed by the pioneering Nobel Prize winning chemist Harold Urey. For basalt amendment of soils, Planavsky’s team use triple isotope spiked cocktail (24/26Mg, 42/44Ca, 48/49Ti) to reduce the measurement error in quantifying elemental loss from the soil-applied basalt.
Provisional analyses of time-series of soils from our Energy Farm trials shows a coherent pattern of rising atmospheric CO2 removal potential over time in response to ERW treatments (see below). This promises to be a significant advance in that it allows us to compare modelled weathering rates of basalt minerals, and release of cations, with direct measurements from field trials. It thus creates valuable and important opportunities for linking across Themes 1 and 3. Further detailed analyses of the Energy Farm soils are underway, together with pilot studies of the technique from our other two ERW field trial sites; oil palm in Malaysian Borneo and sugarcane in Northern Australia.
2022-2023
Basalt plots at the University of Illinois Energy Farm received the third application of Pioneer Valley Basalt in November 2022, bringing total applications to seven events. No basalt was applied to miscanthus in the spring of 2023, initiating the ‘ramping-down’ phase of the research. Residual basalt in the soil from the five previous applications in miscanthus is expected to continue to weather and provide soil pH and plant growth benefits into the future. Measurements of N2O production, soil respiration, soil pH, and soil water chemistry will continue in miscanthus as well as maize to determine factors like basalt persistence and optimal application interval.
In 2022-2023 a partial carbon budget was prepared for the Energy Farm maize/soy and miscanthus fields with and without enhanced rock weathering. Soil and plant carbon measurements, along with soil respiration and eddy covariance measurements of gas exchange, were combined to compare the plant-driven components of the carbon cycle. Collaborators from Eion Corp developed a technique for calculating carbon dioxide capture potential from basalt application, as well as forensically quantifying basalt application rate itself, using a rare earth element approach to track the minor component elements of basalt which are left behind in the soil during the weathering process (see below). The calculated carbon dioxide reduction by enhanced weathering was used to quantify the effects of EW on measured components of the C budget, as well as the overall improvement in C capture with basalt application. Calculations showed that the CDR by EW reduced carbon loss to the atmosphere by 42% in maize plots. In miscanthus plots, where carbon storage outweighed loss to the atmosphere, EW practices more than doubled carbon storage, demonstrating measurable positive impacts with this soil amendment approach.
2023-2024
Maize fields at the University of Illinois Energy Farm have received four applications of Blue Ridge basalt and four applications of Pioneer Valley basalt as of Spring 2024 (see below). There have been no negative effects on yield or grain quality with basalt application, and increases in yield have been observed in some years with both basalt types. Soil pH in basalt-treated maize plots remains elevated compared with control plots, while both treatment and control experience similar seasonal variations in pH.
Miscanthus plots, which have received no new basalt since Spring 2022, maintained elevated soil pH in the surface soils (0-10 cm) compared with control plots through 2023. In deeper soils (10-30 cm), both treatments showed an early season decline in soil pH that follows trends observed in previous years. Miscanthus yields in 2023 were not different between basalt-treated and control plots, where a yield increase with basalt application was measured in 2020 and 2021.
Continued measurements of nitrous oxide production in maize showed no significant differences between control, basalt, and lime-treated plots in 2023. In 2024, measurements of nitrous oxide production are paired with isotopic pool dilution measurements to disentangle the mechanisms controlling nitrogen cycling and release in basalt-treated maize. This method introduces stable isotope tracers to the soil gas collection chambers used in the field, and the dilution and consumption of the two tracers measure the production and consumption of N2O by soil organisms.
Extremely dry conditions in February of 2024 in Illinois limited soil water collection, however rainfall returned to normal in March and was well above average in April, leading to increased late-season soil water and tile drain collection. Soils were collected in Spring 2024 from maize control and basalt plots for uXRF analysis of soil structure and composition.
![Partial carbon budgets for a maize [(a) average of 2017, 2018, 2020], and soybean [(a) right; 2018] grown with or without basalt amendment.](http://cdn.sheffield.ac.uk/sites/default/files/styles/mobile_single_column_1x/public/2025-04/2023-2024%201st%20Image%20Partial%20carbon%20budgets%20for%20a%20maize%20average%20and%20soybean%20average%20with%20or%20without%20basalt%20amendment.png.jpg?itok=wK8jI74A)
2024-2025
The 2024 growing season was the first year of basalt ‘drawdown’ in maize, the period post-basalt application when no new material was added to the site. Measurements of N2O, soil pH, soil water, and plant biomass continued in soybeans in 2025 (second year of drawdown) and miscanthus (third year of drawdown). Deep soil (> 1m) soil cores were taken in maize/soy fields in the autumn of 2024 and miscanthus fields in spring 2025 to study soil carbon and secondary mineral formations in the soil. The isotopic pool dilution experiment continues in the row crops, seeking to determine the nitrogen dynamics in this system. As 2025 is a soybean year in the Illinois crop rotation, no fertilizer was applied in the spring of 2025, resulting in reduced N2O production from the field. Ongoing work with the DayCent model will use N2O data from the Energy Farm site to develop a partial nitrogen budget for the row crops under basalt treatment.
Papers featuring our Illinois field site
Beerling, D.J., Kantzas, E.P., Lomas, M.R., Taylor, L.L., Zhang, S., Kanzaki, Y., Eufrasio, R.M., Renforth, P., Mecure, J-F., Pollitt, H., Holden, P.B., Edwards, N.R., Koh, L., Epihov, D.Z., Wolf, A., Hansen, J.E., Banwart, S.A., Pidgeon, N.F., Reinhard, C.T., Planavsky, N.J. & Val Martin, M. (2025) Transforming US agriculture for carbon removal with enhanced weathering. Nature. https://doi.org/10.1038/s41586-024-08429-2 Published 5 February 2025.
Epihov, D.Z., Banwart, S.A., McGrath, S.P., Martin, D., Kantola, I.B., Masters, M.D., DeLucia, E.H. & Beerling, D.J. (2024) Iron chelation in soil: a scalable biotechnology for accelerating carbon removal by enhanced weathering of basalt. Environmental Science & Technology.https://doi.org/10.1021/acs.est.3c10146 Published 24 June 2024.
Beerling, D.J., Epihov, D.Z., Kantola, I.B., Masters, M.D., Reershemius, T., Planavsky, N.J., Reinhard, C.T., Jordan, J.S., Thorne, S.J., Weber, J., Martin, M.V., Freckleton, R.P., Hartley, S.E., James, R.H., Pearce, C.R., DeLucia, E.H. & Banwart, S.A. (2024) Enhanced weathering in the US Corn Belt delivers carbon removal with agronomic benefits. Proceedings of the National Academy of Science of the United States of America 121(9), e2319436121. Published 22 February 2024.
Val Martin, M., Blanc-Betes, E., Fung, M.K., Kantzas, E.P., Kantola, I.B., Chiaravalloti, I., Taylor, L.L., Emmons, L.K., Wieder, W.R., Planavasky, N.J., Masters, M.D., DeLucia, M.D., Tai, A.P.K. & Beerling, D.J. (2023) Improved nitrogen cycle in a land surface model (CLM5) to quantity soil N2O, NO, and NH3 emissions from enhanced weathering with croplands. Geoscientific Model Development, 16, 5783-5801. https://doi.org/10.5194/gmd-16-5783-2023. Published 18 October 2023.
Kantola, I.B., Blanc-Betes, E., Masters, M.D., Chang, E., Marklein, A., Moore, C.E., von Haden, A., Bernacchi, C.J., Wolf, A., Epihov, D.Z., Beerling, D.J. & DeLucia, E.H. (2023). Improved net carbon budgets in the US Midwest through direct measured impacts of enhanced weathering. Global Change Biology, 00, 1–17. https://doi.org/10.1111/gcb.16903. Published 17 August 2023.
Gomez-Casanoas, N., Blanc-Betes, E., Moore, C. E., Bernachi, C. J., Kantola, I. & DeLucia, E. H. (2021) A review of transformative strategies for climate mitigation by grasslands. Science of the Total Environment, 799, 149466. https://doi.org/10.1016/j.scitotenv.2021.149466. Published online 4 August 2021.
Lewis, A. L., Sarkar, B., Wade, P., Kemp, S. J., Hodson, M. E., Taylor, L. L., Yeong, K. L., Davies, K., Nelson, P. N., Bird, M. I., Kantola, I. B., Masters, M. D., DeLucia, E., Leake, J. R., Banwart, S. A. & Beerling, D. J. (2021) Effects of mineralogy, chemistry and physical properties of basalts on carbon capture potential and plant-nutrient element release via enhanced weathering. Applied Geochemistry, 132. https://doi.org/10.1016/j.apgeochem.2021.105023. Published 21 June 2021.
Blanc-Betes, E., Kantola, I. B., Gomez-Casanovas, N., Hartman, M. D., Parton, W. J., Lewis, A. L., Beerling, D. J. & DeLucia, E. H. (2020) In silico assessment of the potential of basalt amendments to reduce N2O emissions from bioenergy crops. GCB Bioenergy, 13, 224-241. https://doi.org/10.1111/gcbb.12757. Published 7 October 2020.
Beerling, D.J., Leake, J.R., Long, S.P., Scholes, J.D., Ton, J., Nelson, P.N., Bird, M.I., Kantzas, E., Taylor, L.L., Sarkar, B., Kelland, M., DeLucia, E., Kantola, I., Müller, C., Rau, G. & Hansen, J. (2018) Farming with crops and rocks to address global climate, food and soil security. Nature Plants, 4, 138-147. https://doi.org/10.1038/s41477-018-0108-y. Published 19 February 2018.
Kantola, I.B., Masters, M.D., Beerling, D.J., Long, S.P. & DeLucia, D.H. (2017) Potential of global croplands and bioenergy crops for climate change mitigation through deployment for enhanced weathering. Biology Letters, 13, 20160714. https://doi.org/10.1098/rsbl.2016.0714. Published 5 April 2017 as part of the mini-series “Enhanced rock weathering: biological climate change mitigation with co-benefits for food security”.