Nitrogen deposition weakens soil carbon control of nitrogen dynamics across the contiguous United States
Data files
Jan 02, 2025 version files 11.86 MB
-
CASTNET_data.csv
211.24 KB
-
NADP_data.csv
7.82 KB
-
NCycling2020_2021_data.csv
7.16 KB
-
README.md
4.59 KB
-
Soil_data.csv
13.15 KB
-
Weather_data.csv
11.62 MB
Abstract
Anthropogenic nitrogen (N) deposition is unequally distributed across space and time, with inputs to terrestrial ecosystems impacted by industry regulations and variation in human activity. Soil carbon (C) content normally controls the fraction of mineralized N that is nitrified (ƒnitrified), affecting N bioavailability for plants and microbes. However, it is unknown whether N deposition has modified the relationships between soil C, net N mineralization, and net nitrification. To test whether N deposition alters the relationship between soil C and net N transformations, we collected soils from coniferous and deciduous forests, grasslands, and residential yards in 14 regions across the contiguous U.S. that vary in N deposition rates. We quantified rates of net nitrification and N mineralization, soil chemistry (soil C, N, and pH), and microbial biomass and function (as beta-glucosidase (BG) and N-acetylglucosaminidase (NAG) activity) across these regions. Following expectations, soil C was a driver of ƒnitrified across regions, whereby increasing soil C resulted in a decline in net nitrification and ƒnitrified. The ƒnitrified value increased with lower microbial enzymatic investment in N acquisition (increasing BG:NAG ratio) and lower active microbial biomass, providing some evidence that heterotrophic microbial N demand controls the ammonium pool for nitrifiers. However, higher total N deposition increased ƒnitrified, including for high soil C sites predicted to have low ƒnitrified, which decreased the role of soil C as a predictor of ƒnitrified. Notably, the drop in contemporary atmospheric N deposition rates during the 2020 COVID-19 pandemic did not weaken the effect of N deposition on relationships between soil C and ƒnitrified. Our results suggest N deposition can disrupt the relationship between soil C and net N transformations, with this change potentially explained by weaker microbial competition for N. Therefore, past N inputs and soil C should be used together to predict N dynamics across terrestrial ecosystems.
README: Nitrogen deposition weakens soil carbon control of nitrogen dynamics across the contiguous United States
https://doi.org/10.5061/dryad.g79cnp611
Description of the data and file structure
Soils were collected across the contiguous United States as an effort to understand the biogeochemical responses to the COVID-19 pandemic. Data associated with sites were used to describe the characteristics of each site's climate and atmospheric nitrogen deposition.
NA: Not applicable
Files and variables
File: Soil_data.csv
Description: Carbon and nitrogen cycling data for the main analysis of the text.
Variables
- Region: Name of the region the soil was collected.
- Site: Name of the site within the region that soil was collected.
- Date: Date of soil collection (MM/DD/YY).
- Plot: Plot number.
- MAT: 30-year mean annual temperature of the closest weather station in the National Weather Service Cooperative Network (degrees Celsius).
- MAP: 30-year mean annual precipitation of the closest weather station in the National Weather Service Cooperative Network (millimeters).
- GravimetricWaterContent: Gravimetric moisture content of soil sample (grams water grams-1 dry soil).
- SoilpH: pH of soil slurry (1:2 volumetric ratio of soil and deionized water) (unitless).
- ActiveMicrobialBiomass_SIR: Rate of maximum CO2 production from the addition of labile carbon (micrograms CO2-C grams-1 dry soil hour-1).
- Net_NMineralization: Rate of net change of inorganic nitrogen (NH4 + NO3) after 28 days of laboratory incubation (micrograms N grams-1 dry soil day-1).
- Net_Nitrification: Rate of net change of nitrate (NO3) after 28 days of laboratory incubation (micrograms N grams-1 dry soil day-1).
- BG_activity: Maximum potential betaglucosidase activity (nanomoles substrate grams-1 dry soil hour-1).
- NAG_activity: Maximum potential N-acetyl-glucosaminidase activity (nanomoles substrate grams-1 dry soil hour-1).
- SoilC: Total soil carbon (%).
- SoilN: Total soil nitrogen (%).
File: NCycling2020_2021_data.csv
Description: Nitrogen cycling data for the main analysis of the text comparing years 2020 and 2021.
Variables
- Region: Name of the region the soil was collected.
- Site: Name of the site within the region that soil was collected.
- Date: Date of soil collection (MM/DD/YY).
- Plot: Plot number.
- Net_NMineralization: Rate of net change of inorganic nitrogen (NH4 + NO3) after 28 days of laboratory incubation (micrograms N grams-1 dry soil day-1).
- Net_Nitrification: Rate of net change of nitrate (NO3) after 28 days of laboratory incubation (micrograms N grams-1 dry soil day-1).
File: NADP_data.csv
Description: National Trends Network data from the National Atmospheric Deposition Program. Data were accessed online on November 14, 2023.
Variables
- Region: Name of the region the soil was collected.
- Site: Name of the site within the region that soil was collected.
- Year: Year of annual atmospheric deposition.
- TotalN_deposition: Yearly rate of atmospheric total N deposition (kilograms N hectare-1 year-1).
- NH4Wet_deposition: Yearly rate of atmospheric wet ammonium (NH4) deposition (kilograms N hectare-1 year-1).
File: CASTNET_data.csv
Description: Clean Air Status and Trends Network data from the U.S. Environmental Protection Agency. Data were accessed online on February 14, 2024.
Variables
- Station: Name of the CASTNET station.
- Year: Year of annual dry N atmospheric deposition.
- Week: Week of year.
- DateOn: Day started for collection week.
- DateOff: Day ended for collection week.
- NH4: Weekly rate of dry NH4-N deposition (kilograms N hectare-1 week-1).
- NO3: Weekly rate of dry NO3-N deposition (kilograms N hectare-1 week-1).
File: Weather_data.csv
Description: Daily weather data from the National Weather Service Cooperative Network. These data were used to calculate monthly precipitation and potential evapotranspiration to identify climate.
Variables
- Region: Name of the region the soil was collected.
- Site: Name of the site within the region that soil was collected.
- Name: Name of weather station.
- Station: Station identification.
- Date: Date of year (MM/DD/YY).
- Precip: Daily precipitation (millimeters).
- TMax: Maximum temperature (degrees Celsius).
- TMin: Minimum temperature (degrees Celsius).
- Latitude: Latitude of weather station.
Code/software
Data were analyzed using R (V4.3.3) within the RStudio environment (V2023.12.1+402).