Because of the lack of unbiased information on the value of this rock to farmers, we reached out to the enhanced rock weathering company (Lithos Carbon, LLC) to establish a replicated on-farm trial comparing two rates of basalt rock with the recommended rate of high-calcium ag limestone, and also including a control with no rock at all applied. This field experiment was initiated on a Frederick County farm in October 2023 when the company spread rock powder treatments (including both their basalt powder and high-calcium ag lime) on a total of 16 plots, each 60 ft wide by 550 ft long. The experiment was set up to straddle two different types of soils represented in the field, one limestone-derived and one derived from shale. Therefore, if we are funded to do the research the results would apply to a large swath of central Maryland and southern Pennsylvania.

We are asking the Maryland Soybean Board for funding to conduct research on these plots now that they are established. We want to periodically measure the pH at different soil depths to determine how the basalt rock compares to the ag limestone in terms of the rate and depth with which it neutralizes the soil acidity. We propose to study the effects on the growth, nutrient content, and yield of winter wheat (which was planted in late October 2023) and double-crop soybean (to be planted after wheat harvest in July 2024). We also want to determine how much bicarbonate is in the water leaching from this field to confirm that this enhanced rock weathering is actually removing carbon dioxide from the atmosphere and thus producing valuable carbon credits.
This will be a cutting-edge and complex research project involving sophisticated deep soil sampling and collection of leaching water from 32 locations in the field. We are fortunate that a current instructor in the ENST department at the University of Maryland is interested in using this experiment for her PhD research. Since she is a University employee, she will not have to pay tuition and her salary is already funded for nine months of the year. With this grant, we are asking the Maryland Soybean Board to support her as a PhD student for two months in the summer. Therefore, this grant would leverage a two-month stipend into a PhD student dedicated to this research. Since the applied basalt powder will take several years to complete weather, and effects on soil properties and crop health may take several years to become apparent we are proposing a three-year research project.
Applying powdered basalt rock to acid soils may cause a million years of rock weathering to occur in just a few years. This rock material may have the potential to benefit soil health and save money for farmers. Since farmers already apply limestone rock, this practice may be easily scalable to the point where it could significantly help reverse climate change and ocean acidification. We propose here to do three years of proof-of-concept research on plots already treated with rock materials.

1. Compare powdered basalt to traditionally used powdered limestone for neutralizing agricultural soil acidity.
2. Measure the rate of pH change over time and with soil depth and spatially across soil types in the field.
3. Measure any effects on soil physical condition such as aggregate stability, infiltration rate, structure, dispersion, and water holding capacity.
3. Measure any positive or negative effects on soybean and wheat crop growth, composition, and yield.
4. Measure bicarbonate produced when basalt reacts with carbonic acid in soil and trace its leaching through the profile.

On October 23, 2023 four treatments were applied to the respective plots,
1. Control with no rock material added.
2. Recommended amount of ag lime (2.5 tons/acre) to raise the pH to a 6.5 target.
3. The amount (7.5 tons/acre) of basalt rock powder estimated by geochemical models to achieve the same rise on soil pH.
4. Twice the recommended basalt rate {15 tons/acre).

Immediately after the rock materials were spread, the land was lightly disked twice to a depth of 3 inches to smooth previously existing tracks and ridges and to mix the rock powder with the soil. Winter wheat was then drilled and a good stand was achieved.

Soil samples will be collected periodically from a 60 x 30 ft {1800 ft2) sampling area near the upslope and downslope ends of each of the 16 plots (32 sampling areas in total, 8 for each of the four treatments).
After soybeans were harvested from the field, baseline composite soil samples from 0-10, 10-20 and 20- 30 cm were collected (10 cores per sampling area) were collected on October 15-17, 2023. The same soil sampling scheme will be used to collect samples in April, June, Sept, November 2024 and February or March 2025 allowing us to determine the change in soil pH at three depths and over an 18 month period after the rock application.


In April-May 2024 suction lysimeters will be installed to allow the collection of soil macropore drainage water from 60 and 90 cm deep. Two lysimeters will be installed in each plot, for a total of 32. The lysimeters will be installed under cast iron manhole covers to allow them to remain installed during farming operations. Drainage water samples will be collected approximately every 2-3 weeks as weather allows between April 2024 and March 2025.

Measurement of pH, electrical conductivity, total alkalinity and total dissolved carbonates will be performed on drainage water samples. The bicarbonates will be analyzed using a calcimetry apparatus (Eigelkamp). The 0-10 cm soil samples from two dates will be analyzed for soil dispersion, aggregate stability and water holding capacity.
Wheat plant tissue (whole plant) will be collected in April and analyzed for elemental content. Wheat grain sampled at harvest in early July will also be analyzed. Wheat yield will be measured using a calibrated yield monitor in a 22 ft wide strip down the middle of each 60 ft wide plot.

Deep cores to 120-150 cm in a transect of 5 cores in each plot will be collected 16 to 18 months after rock powder application in March-April 2025. These cores will be divided into four to five 30 cm increments, dried, ground and analyzed for soil pH, EC, total bicarbonates, alkalinity, and plant available sulfur, phosphorus, calcium, magnesium, potassium and micronutrients.
Double crop soybeans will be no-till planted within a few days of wheat harvest. Soybean stand counts will be taken in late July and whole soybean plants will be sampled at first flower and soybean seeds sampled at harvest maturity. These samples will be analyzed for elemental contents. Soybean yields will be measured in a 22 ft wide strip down the middle of each plot using a calibrated yield monitor.

Updated July 23, 2024:

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Farmer will have access to unbiased data to inform their decision whether to accept offers of free or low­ cost basalt rock application as a substitute for ag lime. Basalt application rates will be more accurately determined to be equivalent to recommended lime rates. Farmers will be warned if any detrimental side effects are detected and informed of any positive effects on soil properties and crop yields from using basalt.