Spatiotemporal soil fertility responses to an enhanced rock weathering deployment within a temperate, agricultural watershed
Quinn Zacharias, Robert Rioux, Fengchao Sun, Wyatt Tatge, Evelin Pihlap,
Emmanuel Nyavor, David Foster, Joshua L. Warren, Mark A. Bradford,
Peter A. Raymond, Noah Planavsky, James E. Saiers
ABSTRACT:
Enhanced rock weathering (ERW) is a promising strategy for removing carbon dioxide
from the atmosphere, yet field-scale observations suitable for evaluating ERW
co-benefits related to soil-fertility improvements within temperate agriculture
settings remain scarce. We conducted a 2.5-year investigation within a headwater
catchment at the Sleepers River Research Watershed in Danville, Vermont, applying
20 t ha⁻¹ of finely milled, calcium-rich meta-basalt to near-stream pastures and
adjacent, upslope hayfields. After establishing a year-long baseline, we continued
to monitor topsoil chemical fertility indicators (pH, exchangeable essential
nutrients, and cation exchange capacity) for 13 months following basalt application
to evaluate changes relative to untreated control transects. The basalt amendment
significantly raised soil pH by 0.15–0.24 units (p < 0.05) and increased exchangeable
calcium by as much as 12%, with larger pH gains in soils that were initially more
acidic. Other nutrients showed only modest responses, partly reflecting slow
dissolution of metamorphic minerals rich in potassium and magnesium. Higher
background variability in the pasture may have muted the detectable basalt-treatment
signal, yet across the hillslope catena the magnitude of pH change scaled inversely
with initial pH (lowest at the shoulder and foot), illustrating the role of land
use and topographic position in modifying ERW responses. These results indicate
that calcium-rich meta-basalt acts as a slow-release liming agent in well-buffered
temperate soils and provide indications of the co-benefits of ERW to improving soil
health within temperate agroecosystems.
from the atmosphere, yet field-scale observations suitable for evaluating ERW
co-benefits related to soil-fertility improvements within temperate agriculture
settings remain scarce. We conducted a 2.5-year investigation within a headwater
catchment at the Sleepers River Research Watershed in Danville, Vermont, applying
20 t ha⁻¹ of finely milled, calcium-rich meta-basalt to near-stream pastures and
adjacent, upslope hayfields. After establishing a year-long baseline, we continued
to monitor topsoil chemical fertility indicators (pH, exchangeable essential
nutrients, and cation exchange capacity) for 13 months following basalt application
to evaluate changes relative to untreated control transects. The basalt amendment
significantly raised soil pH by 0.15–0.24 units (p < 0.05) and increased exchangeable
calcium by as much as 12%, with larger pH gains in soils that were initially more
acidic. Other nutrients showed only modest responses, partly reflecting slow
dissolution of metamorphic minerals rich in potassium and magnesium. Higher
background variability in the pasture may have muted the detectable basalt-treatment
signal, yet across the hillslope catena the magnitude of pH change scaled inversely
with initial pH (lowest at the shoulder and foot), illustrating the role of land
use and topographic position in modifying ERW responses. These results indicate
that calcium-rich meta-basalt acts as a slow-release liming agent in well-buffered
temperate soils and provide indications of the co-benefits of ERW to improving soil
health within temperate agroecosystems.
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