DOI: 10.5061/dryad.x95x69psf
title: Effects of biochar soil amendments on soil properties and plant recruitment in coastal climate change adaptation projects

description: Biochar is a carbon-rich material produced through the pyrolysis of
 organic waste from the agricultural and forestry industries. Because black
 carbon is chemically stable, its application to agricultural fields is
 being touted as a method to mitigate greenhouse gas emissions as it has
 been shown to improve the fertility of the soil and crop yields as well as
 increase carbon sequestration. This data publication archives data from a
 set of paired restoration projects that incorporated biochar soil
 amendments to test the ability of biochar to provide positive ecosystem or
 carbon sequestration benefits.
description: We used two field experiments to help determine whether the
 incorporation of biochar in coastal wetland restoration projects utilizing
 sediment addition promoted plant recruitment, sequestered carbon, or
 altered soil conditions. In the first experiment, replicated field plots
 (13 m<sup>2</sup>) were constructed within a large-scale (50
 ha) sediment addition project, where the effect of 10% (v/v)
 <em>Eucalyptus</em> biochar soil amendments on plant growth
 and soil conditions were examined for three different sediment types. In
 the second experiment, we conducted a replicated field experiment at three
 tidal marshes where we simulated thin layer sediment placement at the
 scale of smaller plots (0.7 m x 0.7 m), examining the effect of two
 different biochar types (softwood biochar and biochar mixed with compost).
 These field experiments allow us to examine any commonalities in the
 effects of biochar incorporation into projects aimed to enhance salt
 marshes' condition and function through sediment additions.
 <em>Landscape-scale Restoration
 Experiment</em> To study the effect of biochar on
 enhancing restoration success in coastal marshes, we sampled several
 large-scale plots established in August 2018 as part of a 50-ha coastal
 restoration project in Central Monterey Bay, CA. The three areas of
 interest each had three large plots (11m x 3.5m) that were designed with
 three nested plots (3.5m x 3.5m) that aimed to compare two different
 sediment types and depth mixtures used in sediment addition projects at
 Elkhorn Slough. These sediment types included granite fines, locally
 available sediment of crushed granite available at low or no cost, and
 floodplain sediments imported from a river channel widening project
 conducted to increase flow capacity and mitigate flooding along the nearby
 Pajaro River. The Pajaro River in the nearby town of Watsonville is a
 flood-prone area that experienced devastating flooding affecting largely
 low-income farm worker communities in 1995 and 2023
 (https://www.pajarowatershed.org/bench-excavation/). Soil compositions
 included: granite fines to a depth of 0.6 m (three 3.5 m x 3.5 m plots
 with biochar and three without), granite fines to a depth of 0.6 m, but
 capped with 15 cm of floodplain sediment (three 3.5 m x 3.5 m plots with
 biochar and three without), a 50/50 mix of granite fines and floodplain
 sediments to a depth of 0.6 m (again three 3.5 m x 3.5 m plots with
 biochar and three without), and reference plots with 100% floodplain
 sediments (nine 3.5 m x 3.5 m plots with biochar and nine
 without). In the summer of 2022, two 50 cc samples were
 collected from each plot using a soil ring ca. 3.5cm diameter and 5 cm
 deep to measure soil characteristics, including KCl-extractable ammonium
 and nitrate, pH, bulk density, redox potential, salinity, and loss on
 ignition (LOI). This yielded a total number of six samples per treatment
 for the three different soil mixtures with granite fines, and 18 samples
 per treatment for the floodplain sediments, for a total of 72 soil samples
 total. Soil nutrients were measured as KCl extractable
 ammonium and nitrate. Sediment samples (10 g wet mass) were extracted with
 a 40 mL 2.0 M KCl solution. The slurries were vortexed and centrifuged,
 and the supernatants vacuum filtrated into Nalgene propylene vials and
 stored frozen. The samples were brought to room temperature and were
 analyzed for NH3+4-N and
 NO<sub>3<sup>-</sup></sub>N using a Lachat QC8500
 Flow Injection Colorimeter, at the Center for Clean Water Technology,
 Stony Brook University. Soil pH was measured on 5 cc samples of 1:1 dry
 sediment to water mixtures (weight/weight) which were vortexed three times
 at one-minute intervals before measures. The pH measures were taken
 directly using a Sensorex pH probe on an Orion Star A211 benchtop pH
 meter. Soil redox was measured on room temperature soil samples using an
 Oakton double-junction gel-filled ORP probe on a SPER Scientific Benchtop
 mV meter, where the probe was surrounded by soil. Soil salinity was
 measured on a 10:1 dilution of water soil: dry soil, utilizing 2.0 g of
 wet mass soil. Samples were vortexed for one minute and then centrifuged
 at 2500 rpm for 10 minutes. Supernatant salinity was measured using a YSI
 Professional multiprobe meter and back-calculated for a 1:1 mixture of
 soil and water. Loss on ignition (LOI), a surrogate for soil organic
 content, was measured as the weight lost upon ignition for four hours at
 550°C of oven-dried samples. Sediments were not dried before measurements
 of pH and salinity. Rather, estimates of oven-dry weight were made for wet
 sediments using the field moist/oven-dry ratio. Sediments were processed
 for particle size distribution after pretreatment with hydrogen peroxide
 and dispersal with sodium hexametaphosphate and analyzed using a Beckman
 Coulter LS 13 300 particle size analyzer. Plant cover
 was assessed using drone images collected yearly in the summer (2018-2023)
 to track restoration progress. Plots were delineated digitally in ArcGIS
 (version 10.3, ESRI, Redlands, CA, USA), and a grid of 50 points was
 placed over each plot; with a visual count made of the number of points
 intersecting vegetation. Carbon dioxide and methane emissions were also
 quantified during the summer of 2022 using an LGR (Los Gatos Research)-ABA
 ultraportable greenhouse gas analyzer, at a sampling density of three
 samples from each plot (<em>n</em>=3 per plot;
 <em>n</em>=12-36 per treatment; 108 measures total). The
 analyzer was connected by nylon tubing to a 0.6 m x 0.3 m transparent
 polycarbonate chamber (42 L) seated to PVC collars installed in the marsh
 soil (30 cm diameter). Gas measurements were conducted for three min per
 incubation. Greenhouse gas fluxes were calculated using chamber volume and
 footprint. The Ideal Gas Law (<em>PV</em> =
 <em>nRT</em>) was used to calculate changes in gas
 concentrations over time using measured air temperatures and atmospheric
 pressure.  <em>Plot-scale Thin-layer Sediment
 Placement Experiment</em> In 2018, we conducted a
 replicated experiment with thin layer sediment placement in small plots
 (0.7 x 0.7 m) at tidal marshes located at eight different national
 estuarine research reserves (in New Hampshire, Massachusetts, Rhode
 Island, Chesapeake Bay, Maryland, Chesapeake Bay, Virginia, North
 Carolina, the San Francisco Estuary, California, and Elkhorn Slough, also
 in California). The goal of this experiment was to evaluate the effects of
 sediment placement on vegetation recovery in low and high marshes and
 compare this to control and reference plots, across a range of
 environmental conditions and in locations with different common plant
 species. Here, we report on the results of biochar incorporation, which
 was conducted at three locations: Elkhorn Slough, in California
 (36.811°N, -121.749°W), Sage Lot Pond marsh, on Cape Cod, Massachusetts
 (41.555°N, -70.511°W), and Prudence Island, Rhode Island (41.650°N,
 -71.342°W). At Elkhorn Slough and Prudence Island, the biochar soil
 amendment was a mixture of biochar and compost (Blacklite mix#6, Pacific
 Biochar, Santa Rosa CA), while at Sage Lot Pond, the biochar soil
 amendment was pure biochar (Blacklite Pure): both biochars were produced
 from a feedstock of softwood forest residue, and the soil amendments were
 incorporated into the sediment additions at 10% v/v. Sites had similar
 salinity regimes (five-year averages of 28-30% at all three sites) but
 varied somewhat in tidal range and mean high water, and tidal
 range. We report on vegetation cover and height tracked
 over time (fall 2017, 2018, 2019, and 2020, as well as spring 2019) in
 plots with 14 cm of sediment added, 14 cm of sediment added with 10%
 biochar amendment, control plots, which were similar plots with no
 sediment or biochar added, and reference plots, which generally were
 higher elevation with more complete plant cover. Plant cover was assessed
 using the point-intercept method for a grid of 25 points. Sediments were
 sampled in the spring of 2019 (20 cc), and processed for KCl extractable
 ammonium, pH, redox, salinity, and loss on ignition, using the methods
 described above. In the summer of 2019, carbon dioxide emissions were
 measured at Waquoit Bay and Elkhorn Slough using a Licor LI-8100A
 automated soil CO<sub>2</sub> flux system with a chamber and
 dome. Collars were placed in areas lacking in vegetation.
description: # Effects of biochar soil amendments on soil properties and restoration
 success in coastal climate change adaptation projects
 [https://doi.org/10.5061/dryad.x95x69psf](https://doi.org/10.5061/dryad.x95x69psf) ### There are five files uploaded as part of this data release: 1. landscape_vegetation.csv - this file details the plant cover derived from drone imagery analysis in 2018-2023 in the landscape scale plots constructed at the Elkhorn Slough National Estuarine Research Reserve. 2. landscape_soil.csv - this file details soil analysis for soils collected in summer 2022 from landscape scale plots. 3. plot_vegetation.csv - this file details the plant cover derived from point-intercept field surveys conducted at Elkhorn Slough National Estuarine Research Reserve, Waquoit Bay National Estuarine Research Reserve, and Prudence Island National Estuarine Research Reserve in November of 2017, September of 2018, March of 2019, August of 2019, and August of 2020. 4. plot_soil.csv - this file details soil analysis for soils collected in March 2019 from small (0.7m x 0.7m) sediment addition plots. 5. particle_size.csv - this file details outputs of grain size analysis for the biochar amended plots for the landscape scale experiment. ## Description of the data and file structure **landscape_vegetation.csv** - This file contains seven fields: site, code, soil, treatment, amendment, date, plant_cover_fraction. The field site refers to which plot was sampled, 1, 2, or 3, where 1 refers to the northernmost series of plots, 2 refers to the middle series of plots, and 3 is the southernmost series of plots. The field code refers to A, B, or C, where A is the series of plots on the left facing south, B refers to the center series of plot facing south, and C is the right series plot facing south. The field soil refers to one of four soil types: hester_soil, which refers to the type of the sediment used in the whole 50-ha restoration, 50_50_mix, a 50:50 mix of granite fines with the restoration sediment, capped_fines a mixture of granite fines capped with restoration soil, or granite_fines alone, which is just granite fines. The field treatment refers to one of four treatments: reference, biochar, fines, or mix, where reference is the same sediment as the rest of the restoration, biochar refers to restoration soil mixed with biochar, fines refers to one of types of granite fine amended soils (see field soil), and mix refers to a mix of granite fine amended soils and biochar. The field amendment refers one of two values, biochar or none, representing biochar amendments or no amendments. The date refers to the date of the drone flight in YYYY-MM-DD format. The plant_cover_fraction refers to the area of the drone image that had plant cover. **landscape_soil.csv** - This file contains 24 fields, including analysis, site, code, replicate, old-Bag-code, new-Bag-code, plant, amendment, plant_cover, LOI, bulk_density, water_fraction, salinity, pH, redox, KCl_NH4, KCl_NO3, D50, sand_frct, mud_frct, silt_frct, clay_frct, sand_fines, CH4_flux_s, CH4_flux_h, CO2_flux. The field analysis refers to one of two codes: GHG or soil, where GHG refers to greenhouse gas flux measures, and soil refers to soil analysis measures. These measures were not taken at the same exact locations and had different numbers of replicates per plot. The field site refers to which plot was sampled, 1, 2, or 3, where 1 refers to the northernmost series of plots, 2 refers to the middle series of plots, and 3 is the southernmost series of plots. The field code refers to A, B, or C, where A is the series of plots on the left facing south, B refers to the center series of plot facing south, and C is the right series plot facing south. The field replicate refers to, where multiple measures are taken in one plot, the replicate number (1 or 2). The field old-Bag-code refers to the code written on the bag. The field new-Bag-code refers to the code which should have been written on the bag. The field plant, may be of two values, 0 or 1, where the value is 1 if the soil was collected beneath a plant or bare soil. The field amendment refers one of two values, biochar or none, representing biochar amendments or no amendments. The field plant_cover refers to field estimated plant cover in the plot, with values from 0-100. The field LOI refers to the organic content of the sediment, as a fraction (0-1). The field bulk_density refers to the bulk density of the soil sample, in g/cc. The field water_fraction is the fraction of the field moist sample that is water. The field salinity is the salinity of the sample, in ppt. The field ORP is redox of the soil sample in mV. The field pH is the pH of the sample on a 1:1 soil to water mix. The field KCl_NH4 is ammonium concentration of KCL extraction (uM / g dry sed). The field KCl_NO3 refers to nitrate concentrations of KCL extraction (uM / g dry sed). The field D50 refers to the median particle size diameter of the sample in micrometers. The field sand_frct refers to the fraction of the sample that is sand (0-1). The field mud_frct refers to the fraction of the sample that is mud (silt and clay) (0-1). The field silt_frct refers to the fraction of the sample that is silt (0-1). The field clay_frct refers to the fraction of the sample that is clay (0-1). The field sand_fines refers to the ratio of sand to mud (silt and clay). The field CH4_flux_s refers to methane emissions (CH4 flux) (in dark flux chambers) in uM/m^2/second. The field CH4_flux_h refers to methane emissions (CH4 flux) (in dark flux chambers) in uM/m2/hour. The field CO2 is soil respiration (CO2 flux) (in dark flux chambers) in uM/m^2/s. Missing data is coded -999. **plot_vegetation.csv** - This file contains eight fields: NERR_code, elevation, plot, treatment, name, cover, date, and time stamp. The NERR_code refers to which site the data was collected at: one of three codes, ELK for Elkhorn Slough, NAR, for Prudence Island, and WQB for Sage Lot Pond, Waquoit Bay. The field elevation is either high or low, as there were five high elevation plots per treatment and five low elevation plots per treatment. The field plot refers to the code of the plot (A, B, C, D, E), or which replicate it is. The field treatment lists one of four treatments: control (a paired plot that received no sediment), reference (a paired plot with high plant cover; the restoration target), 14 (14cm of sediment added) and biochar (14cm of sediment added with 10% biochar admixture). The field name is the plot name that includes the plot, elevation and treatment, H or L for high or low, A, B, C, D, or E for plot, and a code for treatment: 14 cm (14), 14 cm of sediment with biochar (b) reference (R), control (C). The field cover is the percent of the plot that had vegetation cover, with values 0-100. The field date is the date the measure was taken in MM/DD/YEAR. The field timestamp refers to when the measure was taken, before the sediment was added (pre_sediment), during the first year (year1_fall), in the second year during spring (year2_spring), during the second year during fall (year2_fall), and during the third year during fall (year3_fall). Missing data for reference plots is coded -999. **plot_soil.csv** - This file contains 14 fields: NERR_code, date,  elevation,  plot, treatment, name, bulk_density, water_fraction, salinity, ORP, pH, NH4, CO2, vegetation_cover. The NERR_code refers to which site the data was collected at: one of three codes, ELK for Elkhorn Slough, NAR, for Prudence Island, and WQB for Sage Lot Pond, Waquoit Bay. The field date is the date the measure was taken in MM/DD/YEAR. The field elevation is either high or low, as there were five high elevation plots per treatment and five low elevation plots per treatment. The field plot refers to the code of the plot (A, B, C, D, E), or which replicate it is. The field treatment lists one of four treatments: control (a paired plot that received no sediment), reference (a paired plot with high plant cover; the restoration target), 14 (14cm of sediment added) and biochar (14cm of sediment added with 10% biochar admixture). The field name is the plot name that includes the plot, elevation and treatment, H or L for high or low, A, B, C, D, or E for plot, and a code for treatment: 14 cm (14), 14 cm of sediment with biochar (b) reference (R), control (C). The field bulk_density is the bulk density of the soil sample, in g/cc. The field water_fraction is the fraction of the field moist sample that is water. The field salinity is the salinity of the sample, in ppt. The field ORP is redox of the soil sample in mV. The field pH is the pH of the sample on a 1:1 soil to water mix. The field NH4 is ammonium concentration of KCL extraction (uM / g dry sed). The field CO2 is soil respiration (CO2 flux) (in dark flux chambers) in uM/m^2/s. The field vegetation_cover is the year 3 vegetation cover on plots, on a scale of 0-100. The missing or uncollected data is coded -999. **particle_size.csv** - This file has 125 fields, including project, site, code, replicate, old-Bag-code, new-Bag-code, amendment, and 117 codes that reflect particle size bins. The field project has two potential values, landscape or plot. The field site refers to which plot was sampled, 1, 2, or 3, where 1 refers to the northernmost series of plots, 2 refers to the middle series of plots, and 3 is the southernmost series of plots. The field code refers to A, B, or C, where A is the series of plots on the left facing south, B refers to the center series of plot facing south, and C is the right series plot facing south. The field replicate refers to, where multiple measures are taken in one plot, the replicate number (1 or 2). The field old-Bag-code refers to the code written on the bag. The field new-Bag-code refers to the code which should have been written on the bag. The field soil amendment refers one of two values, biochar or none, representing biochar amendments or no amendments. These bins include the following: 0.040  0.044   0.048   0.053   0.058   0.064   0.070   0.077   0.084   0.093   0.102   0.112   0.122   0.134   0.148   0.162   0.178   0.195   0.214 0.235   0.258   0.284   0.311   0.342   0.375   0.412   0.452   0.496   0.545   0.598   0.657   0.721   0.791   0.869   0.953   1.047   1.149  1.261   1.385   1.520   1.669   1.832   2.010   2.207   2.423   2.660   2.920   3.206   3.519   3.862   4.241   4.656   5.111   5.611   6.158     6.761   7.421   8.147   8.944   9.819   10.78   11.83   12.99   14.26   15.65   17.17   18.86   20.70   22.73   24.95   27.38   30.07   33.00  36.24   39.77   43.66   47.93   52.63   57.77   63.41   69.62   76.43   83.90   92.09   101.1   111.0   121.8   133.7   146.8   161.2   176.8  194.2   213.2   234.1   256.8   282.1   309.6   339.8   373.1   409.6   449.7   493.6   541.9   594.9   653.0   716.9   786.9   863.9   948.2   1041 1143    1255    1377    1512    1660    1822    2000. Each of these particle size bins is the percent weight of sediment that falls between the bin labeled (e.g., 2000uM diameter), and the next lowest bin (e.g., 1822 uM). The sum of all the rows of data in the bins equals 100. ## Sharing/Access information There are no other publicly accessible data locations. ## Code/Software No code or software are provided.